Taurine for subgroups of Autism? Plus, vitamin B5 and L Carnitine for KAT6A syndrome?

 

   A Red Bull Formula 1 racing car

 

Today’s post should be of wide interest because it concerns the potential benefit from the OTC supplement taurine. There is a section at the end answering a query about mutations in the KAT6A gene.

Taurine is an amino acid and it is found in abundance in both mother’s milk and formula milk.  It has long been used as a supplement by some people with autism. It is finally going to be the subject of a clinical trial in autism and not surprisingly that will be in China - nowadays home to much autism research.

Taurine is also a key ingredient in energy drinks like Red Bull.

 

In a study of children with autism a third had low levels of taurine. Since taurine has anti-oxidant activity, children with ASD with low taurine concentrations were then examined for abnormal mitochondrial function. That study suggests that taurine may be a valid biomarker in a subgroup of ASD.

Taurine has several potential benefits to those with autism and it is already used to treat a wide variety of other conditions, some of which are relevant to autism. One example is its use in Japan to improve mitochondrial function in a conditional called MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes).

The effects that are suggested to relate to some types of autism include:-

 

·        Activating GABA_A receptors, in the short term

·        Down regulating GABA_A receptors, after long term use

·        Enhancing the PTEN/mTOR/AKT pathway

·        Reverse autophagy impairment caused by microglial activation

·        Reduce NMDA mediated activation of calcium channels

·        Protective effect on mitochondria and upregulating Complex 1

·        Improving the quality of the gut microbiota

 

If you have a pet you may know that taurine is widely given to cats and dogs. All cat food has taurine added and some breeds of dog need supplementation.

Taurine is crucial for several bodily functions in pets, including: 

Heart Health: Taurine helps regulate heart rhythm and improves heart muscle function. It can help prevent a type of heart disease called dilated cardiomyopathy (DCM) in both cats and dogs.

Vision: Taurine plays a role in maintaining healthy vision and can prevent retinal degeneration, a serious eye disease.

Immune System Function: Taurine may help boost the immune system and fight off infections.

 

From China we have the following recent study showing a benefit in the BTBR model of autism:

Taurine Improved Autism-Like Behaviours and Defective Neurogenesis of the Hippocampus in BTBR Mice through the PTEN/mTOR/AKT Signalling Pathway

Effective treatment of patients with autism spectrum disorder (ASD) is still absent so far. Taurine exhibits therapeutic effects towards the autism-like behaviour in ASD model animals. Here, we determined the mechanism of taurine effect on hippocampal neurogenesis in genetically inbred BTBR T⁺ tf/J (BTBR) mice, a proposed model of ASD. In this ASD mouse model, we explored the effect of oral taurine supplementation on ASD-like behaviours in an open field test, elevated plus maze, marble burying test, self-grooming test, and three-chamber test. The mice were divided into four groups of normal controls (WT) and models (BTBR), who did or did not receive 6-week taurine supplementation in water (WT, WT+ Taurine, BTBR, and BTBR+Taurine). Neurogenesis-related effects were determined by Ki67 immunofluorescence staining. Western blot analysis was performed to detect the expression of phosphatase and tensin homologue deleted from chromosome 10 (PTEN)/mTOR/AKT pathway-associated proteins. Our results showed that taurine improved the autism-like behaviour, increased the proliferation of hippocampal cells, promoted PTEN expression, and reduced phosphorylation of mTOR and AKT in hippocampal tissue of the BTBR mice. In conclusion, taurine reduced the autism-like behaviour in partially inherited autism model mice, which may be associa­ted with improving the defective neural precursor cell proliferation and enhancing the PTEN-associated pathway in hippocampal tissue.

 

A trial in humans with autism is scheduled in Guizhou, China. In this trial they seem to believe the benefit may come from modification to the gut microbiota.

 

Study on the Treatment of Taurine in Children With Autism

In the treatment of autism spectrum disorders (ASD), medication is only an adjunct, and the main treatment modalities are education and behavioral therapy. People with autism incur huge medical and educational costs, which puts a great financial burden on families. Taurine is one of the abundant amino acids in tissues and organs, and plays a variety of physiological and pharmacological functions in nervous, cardiovascular, renal, endocrine and immune systems. A large number of studies have shown that taurine can improve cognitive function impairment under various physiological or pathological conditions through a variety of mechanisms, taurine can increase the abundance of beneficial bacteria in the intestine, inhibit the growth of harmful bacteria, and have a positive effect on intestinal homeostasis. This study intends to analyze the effect of taurine supplementation on ASD, and explore the possible mechanism by detecting intestinal symptoms, intestinal flora, markers of oxidative stress and clinical symptoms of ASD.

Taurine granules mixed with corn starch and white sugar, 0.4g in 1 bag, taken orally. One time dosage: 1 bag each time for 1-2 years old, 3 times a day, 1.5 bags each time for 3-5 years old, 3 times a day, 2 bags each time for 6-8 years old, 3 times a day, 2.5-3 bags each time for 9-13 years old, 3 to 4 bags each time for children and adults over 14 years old, 3 times a day. The use of taurine is strictly in accordance with the specifications of Chinese Pharmacopoeia. 

 

Roles of taurine in cognitive function of physiology, pathologies and toxication

Taurine is a key functional amino acid with many functions in the nervous system. The effects of taurine on cognitive function have aroused increasing attention. First, the fluctuations of taurine and its transporters are associated with cognitive impairments in physiology and pathology. This may help diagnose and treat cognitive impairment though mechanisms are not fully uncovered in existing studies. Then, taurine supplements in cognitive impairment of different physiologies, pathologies and toxicologies have been demonstrated to significantly improve and restore cognition in most cases. However, elevated taurine level in cerebrospinal fluid (CSF) by exogenous administration causes cognition retardations only in physiologically sensitive period between the perinatal to early postnatal period. In this review, taurine levels are summarized in different types of cognitive impairments. Subsequently, the effects of taurine supplements on cognitions in physiology, different pathologies and toxication of cognitive impairments (e.g. aging, Alzheimer' disease, streptozotocin (STZ)-induced brain damage, ischemia model, mental disorder, genetic diseases and cognitive injuries of pharmaceuticals and toxins) are analyzed. These data suggest that taurine can improve cognition function through multiple potential mechanisms (e.g. restoring functions of taurine transporters and γ-aminobutyric acid (GABA) A receptors subunit; mitigating neuroinflammation; up-regulating Nrf2 expression and antioxidant capacities; activating Akt/CREB/PGC1α pathway, and further enhancing mitochondria biogenesis, synaptic function and reducing oxidative stress; increasing neurogenesis and synaptic function by pERK; activating PKA pathway). However, more mechanisms still need explorations.

 

Effects and Mechanisms of Taurine as a Therapeutic Agent

Taurine as an inhibitory neuromodulator

Although ER stress assumes an important role in the cytoprotective actions of taurine in the central nervous system (CNS), another important mechanism affecting the CNS is the neuromodulatory activity of taurine. Toxicity in the CNS commonly occurs when an imbalance develops between excitatory and inhibitory neurotransmitters. GABA is one of the dominant inhibitory neurotransmitters, therefore, reductions in either the CNS levels of GABA or the activity of the GABA receptors can favor neuronal hyperexcitability. Taurine serves as a weak agonist of the GABA_A, glycine and NMDA receptors Therefore, taurine can partially substitute for GABA by causing inhibition of neuronal excitability. However, the regulation of the GABA_A receptor by taurine is complex. While acute taurine administration activates the GABA_A receptor, chronic taurine feeding promotes the downregulation of the GABA_A receptor  and the upregulation of glutamate decarboxylase, the rate-limiting step in GABA biosynthesis. Therefore, complex interactions within the GABAeric system, as well as in the glycine and NMDA receptors, largely define the actions of taurine in the CNS.

Pharmacological characterization of GABA_A receptors in taurine-fed mice

Background

Taurine is one of the most abundant free amino acids especially in excitable tissues, with wide physiological actions. Chronic supplementation of taurine in drinking water to mice increases brain excitability mainly through alterations in the inhibitory GABAergic system. These changes include elevated expression level of glutamic acid decarboxylase (GAD) and increased levels of GABA. Additionally we reported that GABAA receptors were down regulated with chronic administration of taurine. Here, we investigated pharmacologically the functional significance of decreased / or change in subunit composition of the GABAA receptors by determining the threshold for picrotoxin-induced seizures. Picrotoxin, an antagonist of GABAA receptors that blocks the channels while in the open state, binds within the pore of the channel between the β2 and β3 subunits. These are the same subunits to which GABA and presumably taurine binds.

Methods

Two-month-old male FVB/NJ mice were subcutaneously injected with picrotoxin (5 mg kg-1) and observed for a) latency until seizures began, b) duration of seizures, and c) frequency of seizures. For taurine treatment, mice were either fed taurine in drinking water (0.05%) or injected (43 mg/kg) 15 min prior to picrotoxin injection. 

Results

We found that taurine-fed mice are resistant to picrotoxin-induced seizures when compared to age-matched controls, as measured by increased latency to seizure, decreased occurrence of seizures and reduced mortality rate. In the picrotoxin-treated animals, latency and duration were significantly shorter than in taurine-treated animas. Injection of taurine 15 min before picrotoxin significantly delayed seizure onset, as did chronic administration of taurine in the diet. Further, taurine treatment significantly increased survival rates compared to the picrotoxin-treated mice. 

Conclusions

We suggest that the elevated threshold for picrotoxin-induced seizures in taurine-fed mice is due to the reduced binding sites available for picrotoxin binding due to the reduced expression of the beta subunits of the GABAA receptor. The delayed effects of picrotoxin after acute taurine injection may indicate that the two molecules are competing for the same binding site on the GABAA receptor. Thus, taurine-fed mice have a functional alteration in the GABAergic system. These include: increased GAD expression, increased GABA levels, and changes in subunit composition of the GABAA receptors. Such a finding is relevant in conditions where agonists of GABAA receptors, such as anesthetics, are administered.

 

Taurine as used in Japan to treat MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes)

Taurine powder 98% "Taisho" [Prevention of stroke-like episodes of MELAS]

Effects of this medicine

This medicine improves mitochondrial dysfunction related to cell energy production etc., and suppresses stroke-like episodes.
It is usually used for prevention of stroke-like episodes of MELAS (mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes).

·         Your dosing schedule prescribed by your doctor is ((        to be written by a healthcare professional))

·         In general, take as following dose according to your weight, 3 times a day after meals. If you weigh less than 15 kg, take 1.02 g (1 g of the active ingredient) at a time. If your weight ranges 15 kg to less than 25 kg, take 2.04 g (2 g) at a time. If your weight ranges 25 kg to less than 40 kg, take 3.06 g (3 g) at a time. If you weigh 40 kg and more, take 4.08 g (4 g) at a time. Strictly follow the instructions.

·         If you miss a dose, take the missed a dose as soon as possible. However, if it is almost time for the next dose, skip the missed a dose and continue your regular dosing schedule. You should never take two doses at one time.

·         If you accidentally take more than your prescribed dose, consult with your doctor or pharmacist.

·         Do not stop taking this medicine unless your doctor instructs you to do so.

 

On the Potential Therapeutic Roles of Taurine in Autism Spectrum Disorder

 

Contemporary research has found that people with autism spectrum disorder (ASD) exhibit aberrant immunological function, with a shift toward increased cytokine production and unusual cell function. Microglia and astroglia were found to be significantly activated in immuno-cytochemical studies, and cytokine analysis revealed that the macrophage chemoattractant protein-1 (MCP-1), interleukin 6 (IL-6), tumor necrosis factor α (TNF-α), and transforming growth factor β-1 (TGFB-1), all generated in the neuroglia, constituted the most predominant cytokines in the brain. Taurine (2-aminoethanesulfonic acid) is a promising therapeutic molecule able to increase the activity of antioxidant enzymes and ATPase, which may be protective against aluminum-induced neurotoxicity. It can also stimulate neurogenesis, synaptogenesis, and reprogramming of proinflammatory M1 macrophage polarization by decreasing mitophagy (mitochondrial autophagy) and raising the expression of the markers of the anti-inflammatory and pro-healing M2 macrophages, such as macrophage mannose receptor (MMR, CD206) and interleukin 10 (IL-10), while lowering the expression of the M1 inflammatory factor genes. Taurine also induces autophagy, which is a mechanism that is impaired in microglia cells and is critically associated with the pathophysiology of ASD. We hypothesize here that taurine could reprogram the metabolism of M1 macrophages that are overstimulated in the nervous system of people suffering from ASD, thereby decreasing the neuroinflammatory process characterized by autophagy impairment (due to excessive microglia activation), neuronal death, and improving cognitive functions. Therefore, we suggest that taurine can serve as an important lead for the development of novel drugs for ASD treatment.

  

Taurine as a potential therapeutic agent interacting with multiple signaling pathways implicated in autism spectrum disorder (ASD): An in-silico analysis

  

Autism spectrum disorders (ASD) are a complex sequelae of neurodevelopmental disorders which manifest in the form of communication and social deficits. Currently, only two agents, namely risperidone and aripiprazole have been approved for the treatment of ASD, and there is a dearth of more drugs for the disorder. The exact pathophysiology of autism is not understood clearly, but research has implicated multiple pathways at different points in the neuronal circuitry, suggesting their role in ASD. Among these, the role played by neuroinflammatory cascades like the NF-KB and Nrf2 pathways, and the excitotoxic glutamatergic system, are said to have a bearing on the development of ASD. Similarly, the GPR40 receptor, present in both the gut and the blood brain barrier, has also been said to be involved in the disorder. Consequently, molecules which can act by interacting with one or multiple of these targets might have a potential in the therapy of the disorder, and for this reason, this study was designed to assess the binding affinity of taurine, a naturally-occurring amino acid, with these target molecules. The same was scored against these targets using in-silico docking studies, with Risperidone and Aripiprazole being used as standard comparators. Encouraging docking scores were obtained for taurine across all the selected targets, indicating promising target interaction. But the affinity for targets actually varied in the order NRF-KEAP > NF-κB > NMDA > Calcium channel > GPR 40. Given the potential implication of these targets in the pathogenesis of ASD, the drug might show promising results in the therapy of the disorder if subjected to further evaluations.

 

Is Taurine a Biomarker in Autistic Spectrum Disorder?

Taurine is a sulfur-containing amino acid which is not incorporated into protein. However, taurine has various critical physiological functions including development of the eye and brain, reproduction, osmoregulation, and immune functions including anti-inflammatory as well as anti-oxidant activity. The causes of autistic spectrum disorder (ASD) are not clear but a high heritability implicates an important role for genetic factors. Reports also implicate oxidative stress and inflammation in the etiology of ASD. Thus, taurine, a well-known antioxidant and regulator of inflammation, was investigated here using the sera from both girls and boys with ASD as well as their siblings and parents. Previous reports regarding taurine serum concentrations in ASD from various laboratories have been controversial. To address the potential role of taurine in ASD, we collected sera from 66 children with ASD (males: 45; females: 21, age 1.5-11.5 years, average age 5.2 ± 1.6) as well as their unaffected siblings (brothers: 24; sisters: 32, age 1.5-17 years, average age 7.0 ± 2.0) as controls of the children with ASD along with parents (fathers: 49; mothers: 54, age 28-45 years). The sera from normal adult controls (males: 47; females: 51, age 28-48 years) were used as controls for the parents. Taurine concentrations in all sera samples were measured using high performance liquid chromatography (HPLC) using a phenylisothiocyanate labeling technique. Taurine concentrations from female and male children with ASD were 123.8 ± 15.2 and 145.8 ± 8.1 μM, respectively, and those from their unaffected brothers and sisters were 142.6 ± 10.4 and 150.8 ± 8.4 μM, respectively. There was no significant difference in taurine concentration between autistic children and their unaffected siblings. Taurine concentrations in children with ASD were also not significantly different from their parents (mothers: 139.6 ± 7.7 μM, fathers: 147.4 ± 7.5 μM). No significant difference was observed between adult controls and parents of ASD children (control females: 164.8 ± 4.8 μM, control males: 163.0 ± 7.0 μM). However, 21 out of 66 children with ASD had low taurine concentrations (<106 μM). Since taurine has anti-oxidant activity, children with ASD with low taurine concentrations will be examined for abnormal mitochondrial function. Our data imply that taurine may be a valid biomarker in a subgroup of ASD.

  

The Role of Taurine in Mitochondria Health: More Than Just an Antioxidant

Taurine is a naturally occurring sulfur-containing amino acid that is found abundantly in excitatory tissues, such as the heart, brain, retina and skeletal muscles. Taurine was first isolated in the 1800s, but not much was known about this molecule until the 1990s. In 1985, taurine was first approved as the treatment among heart failure patients in Japan. Accumulating studies have shown that taurine supplementation also protects against pathologies associated with mitochondrial defects, such as aging, mitochondrial diseases, metabolic syndrome, cancer, cardiovascular diseases and neurological disorders. In this review, we will provide a general overview on the mitochondria biology and the consequence of mitochondrial defects in pathologies. Then, we will discuss the antioxidant action of taurine, particularly in relation to the maintenance of mitochondria function. We will also describe several reported studies on the current use of taurine supplementation in several mitochondria-associated pathologies in humans.

 

Taurine is known not as a radical scavenger. Several potential mechanisms by which taurine exerts its antioxidant activity in maintaining mitochondria health include: taurine conjugates with uridine on mitochondrial tRNA to form a 5-taurinomethyluridine for proper synthesis of mitochondrial proteins (mechanism 1), which regulates the stability and functionality of respiratory chain complexes; taurine reduces superoxide generation by enhancing the activity of intracellular antioxidants (mechanism 2); taurine prevents calcium overload and prevents reduction in energy production and the collapse of mitochondrial membrane potential (mechanism 3); taurine directly scavenges HOCl to form N-chlorotaurine in inhibiting a pro-inflammatory response (mechanism 4); and taurine inhibits mitochondria-mediated apoptosis by preventing caspase activation or by restoring the Bax/Bcl-2 ratio and preventing Bax translocation to the mitochondria to promote apoptosis (mechanism 5).

Taurine Forms a Complex with Mitochondrial tRNA

Taurine Reduces Superoxide Generation in the Mitochondria

Taurine Regulates Intracellular Calcium Homeostasis

Taurine Inhibits Mitochondria-Mediated Apoptosis

 

Taurine therapy, therefore, could potentially improve mitochondrial health, particularly in mitochondria-targeted pathologies, such as cardiovascular diseases, metabolic diseases, mitochondrial diseases and neurological disorders. Whether the protective mechanism on mitochondria primarily relies on the taurine modification of mitochondrial tRNA requires further investigation.

 

Taurine and the gut microbiota 

We now regularly in the research see that you can make changes in the gut microbiota to treat medical conditions. I think the most interesting was the discovery that the ketogenic diet, used for a century to treat epilepsy, actually works via the high fat diet changing the bacteria that live in your gut; it has nothing at all to do with ketones. UCLA are developing a bacteria product that will mimic the effect of this diet.

We should not be surprised to see that one mode of action put forward for Taurine is changes it makes in the gut microbiota.  It is this very mechanism that the Chinese researchers think is relevant to its benefit in autism.

The paper below is not about autism, but it is about Taurine’s effect on the gut microbiota.

Effects of Taurine on Gut Microbiota Homeostasis: An Evaluation Based on Two Models of Gut Dysbiosis

Taurine, an abundant free amino acid, plays multiple roles in the body, including bile acid conjugation, osmoregulation, oxidative stress, and inflammation prevention. Although the relationship between taurine and the gut has been briefly described, the effects of taurine on the reconstitution of intestinal flora homeostasis under conditions of gut dysbiosis and underlying mechanisms remain unclear. This study examined the effects of taurine on the intestinal flora and homeostasis of healthy mice and mice with dysbiosis caused by antibiotic treatment and pathogenic bacterial infections. The results showed that taurine supplementation could significantly regulate intestinal microflora, alter fecal bile acid composition, reverse the decrease in Lactobacillus abundance, boost intestinal immunity in response to antibiotic exposure, resist colonization by Citrobacter rodentium, and enhance the diversity of flora during infection. Our results indicate that taurine has the potential to shape the gut microbiota of mice and positively affect the restoration of intestinal homeostasis. Thus, taurine can be utilized as a targeted regulator to re-establish a normal microenvironment and to treat or prevent gut dysbiosis.

  

Conclusion

Your body can synthesize taurine from other amino acids, particularly cysteine, with the help of vitamin B6. In most cases, this internal production is enough to meet your daily needs for basic bodily functions.

Infants and some adults may need taurine added to their diet.

Based on the small study in humans, about a third of children with autism have low levels of taurine in their blood.

Is extra taurine going to provide a benefit to the other two thirds?

Taurine looks easy to trial. It is normally taken three times a day after a meal. Each dose would be 0.4g to 4g depending on weight and what the purpose was. The 2 year olds in the Chinese autism trial will be taking 0.4g three times a day. Japanese adults with mitochondrial disease (MELAS) are taking 4g three times a day.

One can oF Red Bull contains 1g of taurine. Most supplements contain 0.5 to 1g. This is a similar dose to what is given to pet cats and dogs. Just like Red Bull contains B vitamins, so do the taurine products for cats and dogs. 

Some of the effects will be immediate, while others will take time to show effect. For example there can potentially be an increase in mitochondrial biogenesis. I expect any changes in gut bacteria would also take a long time to get established.

The effect via GABA on increasing brain excitability is an interesting one for people taking bumetanide for autism, where the GABA developmental switch did not take place. Based on the research you could argue that it will be beneficial or indeed harmful.

What I can say is that in Monty, aged 20 with ASD and taking bumetanide for 12 years, he responded very well on the rare occasions he drank Red Bull.

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Vitamin B5 and L carnitine for KATA6A Syndrome

I was asked about KATA6A syndrome recently.  This syndrome is researched by Dr Kelley, the same doctor who coined the term Autism secondary to mitochondrial dysfunction (AMD).

KAT6A Research and Treatment An Update by Richard I Kelley , MD, PHD

Some kids with KATA6A, like Peter below, respond very well to Dr Kelley’s mito cocktail.

 

Peter’s Experience with a Mitochondrial Cocktail

 

Here’s my experience with the mitochondrial cocktail:

– At 4 weeks after the start of the cocktail, Peter became potty-trained during the day without any training. He pulled his pull up off, refused to put it back on.

-At 2 months, Peter started riding his bike with no training wheels and playing soccer. He became able to kick the ball and run after it till he scores.

-At 2.5 months, he started skiing independently. I used to try to teach how to ski since he was 3yo. I used to spend hours and hours picking him up off the snow with no result. I tried different kind of reinforcers (food,..) with no result. After the cocktail, he just went down the hill by himself, He can ski independently now and knows how to make turns.

-At 2-3 months, I started noticing an increased strength in playing ice hockey and street hockey with a better understanding of the game. His typing ability improved too, he used to have severe apraxia while typing (type the letter next to the letter he wants to type…).

-At 3-4 months, Peter’s fingers on the piano became stronger, he became able to play harder songs with less training and less frustration. I also noticed an increase in “common sense” like for example putting his backpack in the car instead of throwing it on the floor next to the car and riding the car without his backpack. Another example, when we go to the public library, he knows by himself that he has to go to the children section, and walks independently without showing him directions to the play area inside the children section. In the past, he used to grab books the time he enters the library, throw a tantrum on the floor. The most important milestone is that Peter started to say few words that I can understand.

-At 11 months, Peter became potty-trained at night. His speech is slowly getting clearer. His fine and gross motor skills are still getting better.

 

Some readers of this blog have been in touch with Dr Kelley and he does give very thorough replies.

Generally speaking, the therapies for mitochondrial diseases/dysfunctions seem to be about avoiding it getting worse, rather than making dramatic improvements. In the case of Peter (above) the effects do look dramatic. There are many other ideas in the research that do not seem to have been translated into therapy.

A study from two years ago does suggest that vitamin B5 and L carnitine should be trialed. 

Pantothenate and L-Carnitine Supplementation Improves Pathological Alterations in Cellular Models of KAT6A Syndrome

Mutations in several genes involved in the epigenetic regulation of gene expression have been considered risk alterations to different intellectual disability (ID) syndromes associated with features of autism spectrum disorder (ASD). Among them are the pathogenic variants of the lysine-acetyltransferase 6A (KAT6A) gene, which causes KAT6A syndrome. The KAT6A enzyme participates in a wide range of critical cellular functions, such as chromatin remodeling, gene expression, protein synthesis, cell metabolism, and replication. In this manuscript, we examined the pathophysiological alterations in fibroblasts derived from three patients harboring KAT6A mutations. We addressed survival in a stress medium, histone acetylation, protein expression patterns, and transcriptome analysis, as well as cell bioenergetics. In addition, we evaluated the therapeutic effectiveness of epigenetic modulators and mitochondrial boosting agents, such as pantothenate and L-carnitine, in correcting the mutant phenotype. Pantothenate and L-carnitine treatment increased histone acetylation and partially corrected protein and transcriptomic expression patterns in mutant KAT6A cells. Furthermore, the cell bioenergetics of mutant cells was significantly improved. Our results suggest that pantothenate and L-carnitine can significantly improve the mutant phenotype in cellular models of KAT6A syndrome.

Next, we analyzed the expression changes of specific genes in treated and untreated conditions. We found that the expression levels of downregulated genes in the mutant KAT6A fibroblasts, such as KAT6A, SIRT1, SIRT3, NAMPT1, Mt-ND6, NDUFA9, PANK2, mtACP, PDH (E1 subunit α2), KGDH (E2 subunit), SOD1, SOD2, and GPX4 were significantly restored after pantothenate and L-carnitine treatment. The proteins encoded by these genes are involved in acetylation-deacetylation pathways, CoA metabolism, mitochondria, and antioxidant enzymes, all of which are critical for intracellular processes in embryonic and childhood development.

 

KAT6A acts as a master regulator by fine-tuning gene expression through chromatin modifications, so we should expect it to have wide ranging effects. All the closest interactions are will other genes that modify gene expression.

 

https://string-db.org/cgi/network?taskId=b9YRZJrlHtMF&sessionId=b1EyJebcKvBK

A useful site is genecards:

https://www.genecards.org/cgi-bin/carddisp.pl?gene=KAT6A

 

KAT6A mutations are indeed linked to microcephaly, a condition characterized by a smaller than average head circumference.

Most autism is associated with hyperactive pro-growth signalling pathways; only a minority is associated with the opposite and this would fit with microcephaly, which is typical in KAT6A.

Microcephaly is a very common feature of Rett syndrome.

Among the features of KAT6A syndrome there will be overlaps with other syndromes.

Dr Kelley analyses amino acids looking for mitochondrial dysfunction. He has found this present in KAT6A, but this is only one treatable feature of the syndrome.

Targeting growth signaling pathways might well be worth pursuing. You would be looking a what works in other people with smaller heads.

I wrote quite a lot about IGF-1 previously in this blog.

It would be highly plausible that these related therapies might be of benefit. The easy one to try is cGPMax, because it is sold OTC. IGF-1 itself might be beneficial, you would have to find a helpful endocrinologist to trial it.

All the therapies of idiopathic autism could be trialed.

If the child has a paradoxical reaction to any benzodiazepine drug, then you know that bumetanide is likely to be beneficial.

Since mitochondrial function is impaired in KAT6A, taurine is another thing to trial.

ER Stress and Protein Misfolding in Autism (and IP3R again) and perhaps what to do about it - Activation of Sigma-1 Chaperone Activity by Afobazole?

Today’s post may require even regular readers to refresh their memories and look up the meaning of some words.

There really is a lot in this post. I had to read it twice.

As is often the case, this post started at the end with the therapy (a trial of Afobazole) and then I just looked at why it might be effective.

Activate Chaparones

Today's post is all about sigma-1 receptors and the many clever things that happen when they are activated.

Even the above diagram showing the effect of Sigma-1R is incomplete!

In the mouse study below, the Russian researchers looked at the effect of Afobazole treatment just over a few days; I think other effects might have developed if they had looked at an extended time period. They focus on Sigma1-R receptors modulating NMDA-based neurotransmission, but there seem to many possible further effects within the Endoplasmic Reticulum that relate specifically to autism. These researchers have published other studies using Afobazole, including recently one on Parkinson's disease. 

Afobazole Alleviates Cognitive Rigidity in Experimental Model of Autism Spectrum Disorders.

The multifactorial nature of ASD precludes the use of its modern genetic models in the study of pharmacologic effects exerted on entire symptomatic complex of autism although they could relate functional correction of ASD with a certain gene. In experiments, the models of idiopathic ASD are based on inbred mice selected by behavioral phenotype. BALB/c mice demonstrate pronounced autism-relevant behavioral phenotype characterized by low level of social relations, high levels of anxiety and aggression, increased brain weight, undeveloped corpus callosum, and lower serotonin concentration in the brain [7,12]. The emotional stress reaction (ESR) in these animals is associated with weaker binding capacity of the benzodiazepine site in GABAA receptor [6]. Transformation of ESR into the cell stress augments reception in the domain responsible for binding the endo- and exogenous ligands of sigma 1 receptor chaperon protein (Sigma1R) [1] responsible for adaptive reactions [8]. In addition, Sigma1R stimulate BDNF and NGF synthesis, promote the growth and arborization of nerve terminals, and control functional activity of potassium, calcium, and chloride ion channels and a variety of neuroreceptors [5,8,13]. Thus, this chaperon protein can be an important player in physiological and pharmacological regulation of ASD features.

Afobazole is a non-benzodiazepine anxiolytic drug that acts via activation of Sigma1R and interaction with MT1 and MT3 melatonin receptors and a regulatory site of MAO-A [4]. Clinical observations showed that Afobazole optimizes psychophysiological parameters in emotionally unstable persons without impairing attention, psychomotor responsiveness, and decision-making alertness in the model of operator work. The drug is characterized by mild activation effect and reduces anxiety, thus promoting adaptation to novel environment [2]. This work was designed to examine the effects of Afobazole on cognitive rigidity in BALB/c mice.

Evidently, enhanced motor activity of Afobazole treated BALB/c mice reflected the anxiolytic effect of this drug, which stimulated exploratory behavior aimed at solving the novel task. Thus, Afobazole improved adaptation to changing environment

The present study revealed the potency of Afobazole to promote retraining and reversal learning of BALB/c mice, which manifested in increased rate of adaptation to novel environment and more effective solution of the modified task. Afobazole interacts with Sigma1R receptors and induces their activation [1]. It cannot be excluded that the anxiolytic effect of Afobazole is accompanied by up-regulation of Sigma1R chaperone functions, because this drug normalizes the stress-induced down-regulation of reception in benzodiazepine site of GABAA receptor [6]. A large cluster of Sigma1R receptor was revealed in the hippocampus that plays a key role in adaptive behavior related to building of spatial cognitive maps, learning, and memory. Sigma1R receptors modulate NMDA-based neurotransmission; they can enhance spontaneous release of glutamate in the hippocampus, potentiate glutamate-induced release of neurotrophic factor, and participate in synaptic plasticity [8]. However, Sigma1R receptors regulate cognitive processes under disturbed neurotransmitter balance only. All these data agree with our previous findings and with the current views on the mechanism of Afobazole action [1,4,5]. Thus, the mode of action and pharmacological effects of Afobazole are promising features, which justify the hopes to use it as an effective remedy to treat cognitive rigidity in ASD patients

More on sigma-1 and NMDA receptors:-

NMDA Receptors Are Upregulated and Trafficked to the Plasma Membrane after Sigma-1 Receptor Activation in the Rat Hippocampus

Sigma-1 receptors (σ-1Rs) are endoplasmic reticulum resident chaperone proteins implicated in many physiological and pathological processes in the CNS. A striking feature of σ-1Rs is their ability to interact and modulate a large number of voltage- and ligand-gated ion channels at the plasma membrane. We have reported previously that agonists for σ-1Rs potentiate NMDA receptor (NMDAR) currents, although the mechanism by which this occurs is still unclear. In this study, we show that in vivo administration of the selective σ-1R agonists (+)-SKF 10,047 [2S-(2α,6α,11R*]-1,2,3,4,5,6-hexahydro-6,11-dimethyl-3-(2-propenyl)-2,6-methano-3-benzazocin-8-ol hydrochloride (N-allylnormetazocine) hydrochloride], PRE-084 (2-morpholin-4-ylethyl 1-phenylcyclohexane-1-carboxylate hydrochloride), and (+)-pentazocine increases the expression of GluN2A and GluN2B subunits, as well as postsynaptic density protein 95 in the rat hippocampus. We also demonstrate that σ-1R activation leads to an increased interaction between GluN2 subunits and σ-1Rs and mediates trafficking of NMDARs to the cell surface. These results suggest that σ-1R may play an important role in NMDAR-mediated functions, such as learning and memory. It also opens new avenues for additional studies into a multitude of pathological conditions in which NMDARs are involved, including schizophrenia, dementia, and stroke.

Afobazole is primarily used to treat mild anxiety.  Indeed it appears that sigma-1 receptor activation ameliorates anxiety through NR2A-CREB-BDNF signalling.  NR2A is a sub-unit of NMDA receptors.

Sigma-1 receptor activation ameliorates anxiety-like behavior through NR2A-CREB-BDNF signaling pathway in a rat model submitted to single-prolonged stress.

It does seem that activating the sigma-1 receptor might be another of those nexuses in treatment, where different dysfunctions in autism might well respond to the same therapy.  Recall how many functions of the Endoplasmic Reticulum are impaired in autism, such as the all important calcium homeostasis. 

It also might account for some of the people with autism that respond to Memantine/Nameda and Donepezil. My old post on IP3R and the endoplasmic reticulum, looked at the interesting hypothesis proposed by Gargus.

Is dysregulated IP3R calcium signaling a nexus where genes altered in ASD converge to exert their deleterious effect?

Components of a typical animal cell:

1.                 Nucleolus

2.                 Nucleus

3.                 Ribosome (little dots)

4.                Vesicle

5.                Rough endoplasmic reticulum

6.                Golgi apparatus (or "Golgi body")

7.                Cytoskeleton

8.               Smooth endoplasmic reticulum

9.               Mitochondrion

10.            Vacuole

11.            Cytosol (fluid that contains organelles)

12.             Lysosome

13.             Centrosome

14.             Cell membrane

Endoplasmic Reticulum (ER) and ER Stress

The endoplasmic reticulum (ER) is the cellular organelle in which protein folding, calcium homeostasis, and lipid biosynthesis occur. Stimuli such as oxidative stress, ischemic insult, disturbances in calcium homeostasis, and enhanced expression of normal and/or folding-defective proteins lead to the accumulation of unfolded proteins, a condition referred to as ER stress.

Prolonged ER stress typically results in cell death by apoptosis; an answer to “where did all the Purkinje cells go?”, in people with severe autism, perhaps.  

ER stress is known to affect "neurite outgrowth", which is all the bits like dendrites. Purkinje cells have the most dendrites.  Loss of Purkinje cells affects your motor skills and the Pukinje cell layer is found to be severely depleted in people with autism. Many people with autism, even some Aspies, have poor motor skills. 

Research shows that exercise suppresses Purkinje cell losss and that the ones remaining in autistic brains are likley dysfunctional. When synaptic pruning works correctly each Purkinje cell in an adult receives only one climbing fiber input, in ASD models there is an abundance of climbing fibers. It does seem that with enough practice you may overcome poor motor skills in autism.

Interestingly, in the research we see that both Atorvastatin and Rosuvastatin enhance neurite outgrowth. Atorvastatin has long been part of my PolyPill for severe autism.

For effective synaptic pruning you need microglia that are not activated, so shift them back to M0.  This is another part of my PolyPill.

Protein folding is the physical process by which a protein chain acquires its native 3-dimensional structure, a conformation that is usually biologically functional.

Molecular chaperones are a class of proteins that aid in the correct folding of other proteins, sigma-1 is one example.

A protein is considered to be misfolded if it cannot achieve its normal native state and function.

Incorrect protein folding is a common feature of neurodegenerative disease.

An emerging approach is to use pharmaceutical chaperones to fold mutated proteins to render them functional.

As will be seen in the research, ER stress is a feature of severe autism and indeed schizophrenia.

The result is that perfect genes do not produce perfect functional proteins.  They produce misfolded perfect proteins that cannot function.

Misfolded proteins can interact with one another and form structured aggregates and gain toxicity through intermolecular interactions, but that would lead to a degenerative brain disease (Alzheimer’s, Huntington’s, Parkinson’s etc).  So, the misfolding in autism, if present, it not catastrophic (except perhaps for those Purkinje cells); but a nice folded shirt does give a better result than a crumpled one. Better keep your proteins neatly folded. 

Is there ER Stress in Autism?

The short answer is yes, at least in the kind of autism that leads to young human brains  being donated to medical research.  

Autism research based on human brain tissue is biased towards severe autism (they can die in childhood), whereas many/most clinical trials are now biased towards mild autism (having participants who are fully verbal and cooperative makes life easier for researchers, but their young brains do not get donated to medical research).   

Altered Expression of Endoplasmic Reticulum Stress-Related Genes in the Middle Frontal Cortex of Subjects with Autism Spectrum Disorder

The endoplasmic reticulum (ER) is an important organelle responsible for the folding and sorting of proteins. Disturbances in ER homeostasis can trigger a cellular response known as the unfolded protein response, leading to accumulation of unfolded or misfolded proteins in the ER lumen called ER stress. A number of recent studies suggest that mutations in autism spectrum disorder (ASD)-susceptible synaptic genes induce ER stress. However, it is not known whether ER stress-related genes are altered in the brain of ASD subjects. In the present study, we investigated the mRNA expression of ER stress-related genes (ATF4, ATF6, PERK, XBP1, sXBP1, CHOP, and IRE1) in the postmortem middle frontal gyrus of ASD and control subjects. RT-PCR analysis showed significant increases in the mRNA levels of ATF4, ATF6, PERK, XBP1, CHOP, and IRE1 in the middle frontal gyrus of ASD subjects. In addition, we found a significant positive association of mRNA levels of ER stress genes with the diagnostic score for stereotyped behavior in ASD subjects. These results, for the first time, provide the evidence of the dysregulation of ER stress genes in the brain of subjects with ASD.

Increase in mRNA levels of endoplasmic reticulum stress genes in the middle frontal gyrus of autism spectrum disorder (ASD) subjects. mRNA levels of endoplasmic reticulum stress genes were determined by qRT-PCR in the middle frontal gyrus of ASD (n = 13) and control (n = 12) subjects. The Ct values were normalized to the mean of 18S and β-actin. a Activating transcription factor 4 (ATF4). b Activating transcription factor 6 (ATF6). c Protein kinase-like endoplasmic reticulum kinase (PERK). d X-box protein 1 (XBP1). e Spliced X-box protein 1 (sXBP1). f CCAAT-enhancer-binding protein homologous protein (CHOP). g Inositol-requiring enzyme 1 (IRE1). * p < 0.05, ** p < 0.01, and *** p < 0.0001 vs. controls.

We found significant increases in ATF4, ATF6, PERK, XBP1, CHOP, and IRE1 mRNA levels in the middle frontal gyrus of ASD subjects. Among these molecules, CHOP is known to interact with the heterodimeric receptors GABA_B1aR/GABA_B2R and inhibits the formation of heterodimeric complexes resulting in the intracellular accumulation and reduced cell surface expression of receptors [34]. Interestingly, decreased levels of GABA_B1R and GABA_B2R have been found in the brain of ASD subjects [35]. What are the downstream mechanism mediating ER stress-induced changes in central nervous system function? One potential mechanism is inflammation. Accumulating evidence suggest that pathways activated by the ER stress response induce inflammation. When activated, all three sensors of the UPR, PERK, IRE1, and ATF6, participate in upregulating inflammatory processes. It is known that PERK and IRE1 activation can interfere with NFκB inhibitory signals, thereby promoting a proinflammatory response [36]. In addition, CHOP has been shown to induce the expression of proinflammatory cytokines such as IL-23 [37]. Moreover, ER stress activates NLRP3 inflammasomes via thioredoxin-interacting protein (TXNIP), leading to increases in proinflammatory cytokine levels [38,39]. In this regard, our earlier studies using the same tissue samples of the present study found increased levels of proinflammatory cytokines IL-1β and IFN-γ in the middle frontal gyrus of ASD subjects [30].

Also, chronic ER stress is known to induce cellular apoptosis through a number of pathways including CHOP, calcium signaling, and microRNAs [40]. Activation of PERK triggers a series of transcriptional responses mediated by ATF4 and CHOP, which in turn inhibit the expression of anti-apoptotic protein Bcl2 and induce pro-apoptotic proteins such as Bcl2-interacting mediator of cell death (BIM) and p53 upregulated modulator of apoptosis (PUMA) [40]. The induction of pro-apoptotic signaling pathway results in the activation of BAX- and BAK-dependent apoptosis at the mitochondria and the activation of the caspase cascade [41]. Interestingly, decrease in Bcl2, but increase in p53 protein levels have been reported in the frontal cortex of ASD subjects [42].

We found that mRNA levels of ER stress genes are positively associated with the stereotyped behavior domain of the ADI-R. It has been shown that autism-associated mutations in NLGN3, which is known to induce ER stress, also increase stereotyped behavior in mice [43]. Similarly, mice lacking CNTNAP2 showed increased repetitive behaviors such as grooming and digging [44], further suggesting that abnormalities in ASD candidate genes implicated in ER stress induce stereotyped behavior in rodents. The present data was collected in a relatively small number of study subjects, which needs further investigation using larger samples before a conclusion can be drawn. Also, the change in gene expression as part of ER stress axis in ASD could be associated with other priming factors functional on different coordinates of this complex neurodevelopmental disorder. Additional studies are warranted to analyze the ER stress-inducing factors with direct relationship to the pathophysiological changes associated with ASD. To further establish a definitive role of ER stress in ASD pathophysiology, the following questions still need to be addressed: (1) Is ER stress in ASD of neurodevelopmental origin? (2) Are there factors other than mutant synaptic proteins that can trigger ER stress leading to ASD phenotype? (3) Is inflammation triggering ER stress or is ER stress triggering inflammation leading to ASD phenotype? (4) Does ER stress induce changes in neural connectivity between key brain regions implicated in ASD pathophysiology? Future studies addressing the above questions might lead to a better understanding of the pathophysiology and provide new avenues of treatment of this disorder.

Cellular stress and apoptosis contribute to the pathogenesis ofautism spectrum disorder

 

Lay Summary

Autism results in significant morbidity and mortality in children. The functional and molecular changes in the autistic brains are unclear. The present study utilized autistic brain tissues from the National Institute of Child Health and Human Development's Brain Tissue Bank for the analysis of cellular and molecular changes in autistic brains. Three key brain regions, the hippocampus, the cerebellum, and the frontal cortex, in six cases of autistic brains and six cases of non‐autistic brains from 6 to 16 years old deceased children, were analyzed. The current study investigated the possible roles of endoplasmic reticulum (ER) stress, oxidative stress, and apoptosis as molecular mechanisms underlying autism. The activation of three signals of ER stress (protein kinase R‐like endoplasmic reticulum kinase, activating transcription factor 6, inositol‐requiring enzyme 1 alpha) varies in different regions. The occurrence of ER stress leads to apoptosis in autistic brains. ER stress may result from oxidative stress because of elevated levels of the oxidative stress markers: 4‐Hydroxynonenal and nitrotyrosine‐modified proteins in autistic brains. These findings suggest that cellular stress and apoptosis may contribute to the autistic phenotype. Pharmaceuticals and/or dietary supplements, which can alleviate ER stress, oxidative stress and apoptosis, may be effective in ameliorating adverse phenotypes associated with autism.

 

Figure 1. Immunoblot analysis of endoplasmic reticulum (ER) stress signals in the autistic cerebellum. Immunoblot analysis of the cerebellum homogenate was performed using p-IRE1a, p-PERK, and total ATF6 antibodies.

  

In summary, we showed the elevation of ER stress signals, oxidative stress, and apoptosis in three regions of autistic brains. Based on these findings, we reason that increased cellular stress and apoptosis in the autistic brain may be associated with the pathogenesis of autism. Because autism is affected by multiple genetic and environmental factors that are case-specific and there are inherent limitations in the postmortem brain, the present observations will need further confirmation in future studies. Further research with larger sample sizes is needed to investigate the association of cellular stress and apoptotic events with the severity and clinical phenotypes of autism.

 

Chaperone Sigma1R mediates the neuroprotective action of afobazole in the 6-OHDA model of Parkinson’s disease

Abstract

Parkinson’s disease (PD) is a progressive neurodegenerative disease with limited treatment options. Therefore, the identification of therapeutic targets is urgently needed. Previous studies have shown that the ligand activation of the sigma-1 chaperone (Sigma1R) promotes neuroprotection. The multitarget drug afobazole (5-ethoxy-2-[2-(morpholino)-ethylthio]benzimidazole dihydrochloride) was shown to interact with Sigma1Rs and prevent decreases in striatal dopamine in the 6-hydroxydopamine (6-OHDA)-induced parkinsonism model. The aim of the present study was to elucidate the role of Sigma1Rs in afobazole pharmacological activity. Using ICR mice we found that administration of afobazole (2.5 mg/kg, i.p.) or selective agonist of Sigma1R PRE-084 (1.0 mg/kg, i.p.) over 14 days normalizes motor disfunction and prevents decreases in dopamine in the 6-OHDA-lesioned striatum. Afobazole administration also prevents the loss of TH + neurons in the substantia nigra. The pre-administration of selective Sigma1R antagonist BD-1047 (3.0 mg/kg, i.p.) abolishes the activity of either afobazole or PRE-084, as determined using the rotarod test and the analysis of striatal dopamine content. The current study demonstrates the contribution of Sigma1Rs in the neuroprotective effect of afobazole in the 6-OHDA model of Parkinson’s disease and defines the therapeutic perspective of Sigma1R agonists in the clinic.                                                                                                                                                

Sigma-1 (σ1) Receptor in Memory and Neurodegenerative Diseases

The sigma-1 (σ₁) receptor has been associated with regulation of intracellular Ca²⁺ homeostasis, several cellular signaling pathways, and inter-organelle communication, in part through its chaperone activity. In vivo, agonists of the σ₁ receptor enhance brain plasticity, with particularly well-described impact on learning and memory. Under pathological conditions, σ₁ receptor agonists can induce cytoprotective responses. These protective responses comprise various complementary pathways that appear to be differentially engaged according to pathological mechanism. Recent studies have highlighted the efficacy of drugs that act through the σ₁ receptor to mitigate symptoms associated with neurodegenerative disorders with distinct mechanisms of pathogenesis. Here, we will review genetic and pharmacological evidence of σ₁ receptor engagement in learning and memory disorders, cognitive impairment, and neurodegenerative diseases, including Alzheimer’s disease, Parkinson’s disease, amyotrophic lateral sclerosis, multiple sclerosis, and Huntington’s disease.

Crosstalk between endoplasmic reticulum stress and oxidative stress in schizophrenia: The dawn of new therapeutic approaches

Highlights

The complete understanding of the pathways and the point of convergence of ER and oxidative stress in schizophrenia is still quite fragmentary.

Neuronal migration along with altered secretion of neurotrophins modulates neuronal circuits and synaptic function during schizophrenia.

Chemical chaperones including Sigma-1 receptor agonists may prevent stress-induced protein misfolding associated with schizophrenia.

ER-stress inhibitors, sigma-1 receptor agonists and gene therapies holds a strong therapeutic potential against schizophrenia.

Disruption of oxidant/anti-oxidant ratio as well as endoplasmic reticulum (ER) stress are thought to be involved in the pathophysiology of schizophrenia. These stresses can lead to impairments in brain functions progressively leading to neuronal inflammation followed by neuronal cell death. Moreover, the cellular stresses are interlinked leading us to the conclusion that protein misfolding, oxidative stress and apoptosis are intricately intertwined events requiring further research into their mechanistic and physiological pathways. These pathways can be targeted by using different therapeutic interventions like anti-oxidants, sigma-1 receptor agonists and gene therapy to treat the neurodegenerative course of schizophrenia. We have also put empahsis on use of synthetic and natural ER stress inhibitors like 4-phenylbutyrate or salubrinal for the treatment of this disorder. This would provide an opportunity to create new therapeutic benchmarks in the field of neuropsychiatric disorders like schizophrenia, dissociative identity disorder and obsessive compulsive disorder.

                                                                                      

Targeting ligand-operated chaperone sigma-1 receptors in the treatment of neuropsychiatric disorders

Current conventional therapeutic drugs for the treatment of psychiatric or neurodegenerative disorders have certain limitations of use. Psychotherapeutic drugs such as typical and atypical antipsychotics, tricyclic antidepressants, and selective monoamine reuptake inhibitors, aim to normalize the hyper- or hypo-neurotransmission of monoaminergic systems. Despite their great contribution to the outcomes of psychiatric patients, these agents often exert severe side effects and require chronic treatments to promote amelioration of symptoms. Furthermore, drugs available for the treatment of neurodegenerative disorders are severely limited.

Areas covered

This review discusses recent evidence that has shed light on sigma-1 receptor ligands, which may serve as a new class of antidepressants or neuroprotective agents. Sigma-1 receptors are novel ligand-operated molecular chaperones regulating a variety of signal transduction, ER stress, cellular redox, cellular survival, and synaptogenesis. Selective sigma-1 receptor ligands exert rapid antidepressant-like, anxiolytic, antinociceptive and robust neuroprotective actions in preclinical studies. The review also looks at recent studies which suggest that reactive oxygen species might play a crucial role as signal integrators at the downstream of Sig-1Rs

Expert opinion

The significant advances in sigma receptor research in the last decade have begun to elucidate the intracellular signal cascades upstream and downstream of sigma-1 receptors. The novel ligand-operated properties of the sigma-1 receptor chaperone may enable a variety of interventions by which stress-related cellular systems are pharmacologically controlled.

Sigma-1 receptor ligands

Sigma-1 receptor ligands used in recent preclinical studies (2007~2010)

Clinically used drugs:

·         Afobazole (5-ethoxy-2-[2-(morpholino)-ethylthio]benzimidazole dihydrochloride): Anxiolytic drug

·         Carbetapentane: Cough suppressant

·         Dextromethorphan (DM): Antitussive drug; DM-quinidine (Q) therapy is effective in reducing pseudobulbar affect in ALS and multiple sclerosis

·         Donepezil: Sigma-1 agonist; acetylcholine esterase inhibitor used in Alzheimer’s disease

·         Fluvoxamine: Clinically used SSRI; Sig-1R agonist

·         Sertraline: Clinically used SSRI with a putative Sig-1R antagonist property

·         Haloperidol: Clinically used antipsychotic; potent, but non selective sigma antagonist

·         Haloperidol-metabolite II (reduced HP, 4-(4-chlorophenyl)-alpha-(4-fluorophenyl)-4-hydroxy-1-piperidinebutanol): In contrast to haloperidol, having higher selectivity to Sig-1Rs

·         Memantine: A novel Alzheimer’s disease medication blocking NMDA glutamate receptors

·         Zonisamide: Anti-Parkinson drug approved in Japan

Involvement of endoplasmic reticulum stress and neurite outgrowth in the model mice of autism spectrum disorder

Implication of Endoplasmic Reticulum Stress in Autism Spectrum Disorder

Autism spectrum disorder (ASD) is categorized as a neurodevelopmental disorder according to the Diagnostic and Statistical Manual of Disorders, Fifth Edition and is defined as a congenital impairment of the central nervous system. ASD may be caused by a chromosomal abnormality or gene mutation. However, these etiologies are insufficient to account for the pathogenesis of ASD. Therefore, we propose that the etiology and pathogenesis of ASD are related to the stress of the endoplasmic reticulum (ER). ER stress, induced by valproic acid, increased in ASD mouse model, characterized by an unfolded protein response that is activated by this stress. The inhibition of neurite outgrowth and expression of synaptic factors are observed in ASD. Similarly, ER stress suppresses the neurite outgrowth and expression of synaptic factors. Additionally, hyperplasia of the brain is observed in patients with ASD. ER stress also enhances neuronal differentiation. Synaptic factors, such as cell adhesion molecule and shank, play important roles in the formation of neural circuits. Thus, ER stress is associated with the abnormalities of neuronal differentiation, neurite outgrowth, and synaptic protein expression. ER stress elevates the expression of the ubiquitin-protein ligase HRD1 for the degradation of unfolded proteins. HRD1 expression significantly increased in the middle frontal cortex in the postmortem of patients with ASD. Moreover, HRD1 silencing improved the abnormalities induced by ER stress. Because other ubiquitin ligases are related with neurite outgrowth, ER stress may be related to the pathogenesis of neuronal developmental diseases via abnormalities of neuronal differentiation or maturation.

Sigma-1 receptor: The novel intracellular target of neuropsychotherapeutic drugs

The sigma-1 receptor localized at the ER modulates via its chaperone activity inter-organelle communications. Sigma-1 receptors thus regulate a variety of cellular events, such as neuronal differentiation, cellular survival, and bioenergetics. By numerous animal studies, these actions of the sigma-1 receptors have been linked to the pathophysiology of certain human diseases such as depression, ischemia, drug abuse, pain, and cancer. Considering the current pharmacotherapy of neuropsychiatric diseases that largely depends on drugs developed based on the monoamine theory, the sigma-1 receptor is expected to serve as a molecule, which provides a novel target of “post-monoamine” drugs, thus bringing a new approach for treatment of patients suffering from neuropsychiatric diseases.

                                                                                                                       

Fig. 1. Molecular functions of the sigma-1 receptor. The sigma-1 receptor possesses two transmembrane domains and mainly localize at the ER membrane. Sigma-1 receptors are clustered at the mitochondria-associated ER membrane (MAM) and ER membranes juxtaposing postsynaptic density of specific types of neurons. The ER lumenal domain of the sigma-1 receptor exerts chaperone activities by which ER membrane proteins are stabilized. The figure depicts the recently reported actions of the sigma-1 receptors including: 1) Sigma-1 receptors associating with BiP stabilizes IP₃ receptors type-3 (IP3R) at the MAM, leading to regulation of Ca²⁺ influx into mitochondria and following ATP production; 2) Sigma-1 receptors stabilize the ER stress sensor IRE1 at the MAM in an ROS-dependent manner, leading to prolongation of the IRE1-XBP1 cell survival signal; 3) Sigma-1 receptors suppress generation of reactive oxygen species (ROS) and following activation of the NFkB signaling (How the sigma-1 receptor regulates ROS generation is unknown); 4) Sterols such as 25-hydroxycholesterol promote the association of sigma-1 receptors with Insig-1 [Collaborating with Insig-1, sigma-1 receptors regulate ER-associated degradation (ERAD) of HMG-CoA reductase and galactosylceramide synthase at the ER]; 5) Sigma-1 receptors regulate the trafficking of potassium channel subunits from the ER to the plasma membrane or processing/secretion of brain-derived trophic factor (BDNF). Sigma-1 receptors likely associate with potassium channel subunits or pro-BDNF at the ER. In spinal neurons, sigma-1 receptors, which colocalize with a K channel subunit are clustered at the ER membrane apposing postsynaptic densities (PSD). How the sigma-1 receptor regulates processing/secretion of BDNF is unknown.  (in the earlier part of this post the mechanism that increases BDNF is explained, if you activate sigma-1R you inevitably will increase BDNF)

Conclusion

In our simplified view of autism, aimed at actually treating it, we should have a list of stresses and what to do about them:-

·        Oxidative stress

·        Nitrosative stress

·        Endoplasmic Reticulum (ER) stress

Reducing oxidative stress has multiple biological and behavioral effects; the overall effect is generally positive.

Reducing endoplasmic reticulum (ER) stress, if present, does look a good idea.  It will have numerous effects; it should even reduce oxidative stress. The sigma-1 chaperone looks like it will have many effects that, on balance, should be positive, but undoubtedly may upset something and produce an overall negative effect in some people – it is inevitable.  I hope the effect on NMDA receptors does not cause a problem where an E/I (excitatory/inhibitory) imbalance is already being treated.

A highly selective sigma-1R agonist, one that does not affect any other receptors, does not exist.

Many psychiatric drugs like antidepressants do affect sigma-1R, but they are not suitable for long term use because of side effects, tolerance, addiction etc.

Afobazole is interesting because clinical trials have shown it to be well tolerated, non-addictive and reasonably effective for the treatment of anxiety.  Afobazole also affects the melatonin receptor MT1, it is not directly sedating but might affect some types of sleep abnormality. 

Afobazole is only researched in Russia, but findings are shared internationally, for example at this conference

The drug was developed, and is currently researched, by the “Research Zakusov Institute of Pharmacology” in Moscow. They recently also published a paper on the use of Afobazole in Parkinson’s disease.  In the Parkinson’s paper (https://www.nature.com/articles/s41598-019-53413-w) the researchers argue the role of the drug is in targeting ER stress, protein misfolding, IP3R etc.  The very things I am suggesting may be relevant to autism in today’s post.

Another interesting drug from the former USSR, though actually from Latvia (now in the European Union) is Mildronate.  I did suggest a long time ago, based on the research studies, that this might be effective to treat people with a lack of the Mitochondrial Complex 1.

I think mitochondrial disease is likely over diagnosed by MAPS-type doctors, but it is a genuine cause/contributing factor to some people’s autism.

So many people are using Mildronate to boost sporting performance and some for academic performance, it is now widely available from the same vendors /platforms selling Afobazole. (eBay, Amazon etc)

The underlying message is that when considering repurposing safe old drugs to treat neurological conditions, consider all of them, including Japanese, Russian and indeed Latvian.

Many interesting novel substances are mentioned in this blog, like Basmisanil  a highly selective negative allosteric modulator of α₅ subunit-containing GABA_A receptors for the treatment of cognitive impairment specifically associated with Down syndrome.  The problem with such novel substances is that they will be ultra expensive and often they fail in their clinical trials and are never commercialized.  Roche cancelled Basmisanil because it failed in the Down Syndrome trial.  Tuning down the response from GABAa receptors containing the α₅ subunit may very well be an effective way to improve cognitive function in some people, but the failure of this trial likely means no new substances will be developed.

While it is okay to write about new drugs in development, the real interest is in applying what can be used today. All four of the following need to be satisfied:

1.     Safe (no/minimal side effects, no tolerance, no addiction, interactions)

2.     Affordable

3.     Available

4.     Effective

Some drugs, not commonly used in Western countries, likely do tick the first 3 points, whether effective in autism depends on the individual sub-type.  Many do look interesting - from Ibudilast (Japan), to Mildronate (Latvia) for Complex 1 mitochondrial disease and perhaps Afobazole (Russia) for some schizophrenia/autism.

Afobazole is a cheap over-the-counter anxiety treatment in Russia.  It is apparently “effective” in the BALB/c mouse model, that may be relevant to autism. BALB/c mice show low sociability, relatively high levels of anxiety and aggressive behaviors, large brain size, underdevelopment of the corpus callosum, and low levels of brain serotonin.

Is Afobazole the answer to ER stress in autism?  If not, then what might be?  The schizophrenia research suggests 4-phenylbutyrate, salubrinal, cordycepin, taurosodeoxycholic acid.  Cordycepin comes from a mushroom that I recall one of our Aspie readers favours.   

This post could go on forever; I think I have made my point, but a little more:-

The lipophilic 4-phenylbutyric acid derivative prevents aggregation and retention of misfolded proteins 

Chemical chaperones prevent protein aggregation. However, the use of chemical chaperones as drugs against diseases due to protein aggregation is limited by the very high active concentrations (mM range) required for mediating their effect. One of the most common chemical chaperones is 4-phenylbutyric acid (4-PBA). Despite its non-favorable pharmacokinetic properties, 4-PBA was approved as a drug to treat ornithine cycle diseases. Here we report that 2-isopropyl-4-phenylbutanoic acid (compound 5) was (2-10 fold) more effective than 4- PBA in several in vitro models of protein aggregation. Importantly, compound 5 reduced the secretion rate of autism-linked Arg451Cys Neuroligin3 (R451C NLGN3).


Protein misfolding, detectable in blood samples, predicts Alzheimer's Disease up to 14 years before onset, perhaps in time to start effective therapy? perhaps targeting sigma-1R, or perhaps with betanin, that pigment in beetroot, that seems to disrupt plaque formation.

Protein misfolding as a risk marker for Alzheimer's disease

                                                           

In symptom-free individuals, the detection of misfolded amyloid-beta protein in the blood indicated a considerably higher risk of Alzheimer's disease -- up to 14 years before a clinical diagnosis was made. Amyloid-beta folding proved to be superior to other risk markers evaluated.