A RORα Agonist for Autism?

Today’s post is again about RORα, which was suggested to be a nexus where different biological dysfunctions that lead to autism may converge. I think you can consider RORα like a dimmer switch on your lights, you need to adjust the brightness to give the effect you want.

Fine tuning RORα to tune autism gene expression

I recently came across some research where the scientist clearly has the same idea. He has been working on a synthetic RORα/γ agonist for some years and has investigated its use as both a cancer therapy and an autism therapy.

I have become rather interested in cancer therapies because there are so many overlaps between what can lead to cancer and what exists in autism. The big research money is of course in cancer research.

Tumor suppressor genes/proteins like PTEN and p53 have been shown to be disturbed in autism, as is Bcl-2. The Bcl-2 family of proteins regulate cell death (apoptosis); some members induce cell death and other inhibit it; the balance is important.

Generally it seems that most people with autism might benefit from more PTEN and Bcl-2. 

Therapeutic Effect of a Synthetic RORα/γ Agonist in an Animal Model of Autism  

Autism is a developmental disorder of the nervous system associated with impaired social communication and interactions as well excessive repetitive behaviors. There are no drug therapies that directly target the pathology of this disease. The retinoic acid receptor-related orphan receptor α (RORα) is a nuclear receptor that has been demonstrated to have reduced expression in many individuals with autism spectrum disorder (ASD). Several genes that have been shown to be downregulated in individuals with ASD have also been identified as putative RORα target genes. Utilizing a synthetic RORα/γ agonist, SR1078, that we identified previously, we demonstrate that treatment of BTBR mice (a model of autism) with SR1078 results in reduced repetitive behavior. Furthermore, these mice display increased expression of ASD-associated RORα target genes in both the brains of the BTBR mice and in a human neuroblastoma cell line treated with SR1078. These data suggest that pharmacological activation of RORα may be a method for treatment of autism. 

The RORs have been linked to autism in human in several studies. In 2010, Nguyen and co-workers reported that RORα protein expression was significantly reduced in the brains of autistic patients and this decrease in expression was attributed to epigenetic alterations in the RORA gene.¹⁵ Additional work from this group demonstrated that multiple genes associated with autism spectrum disorder are direct RORα target genes and suggested that reduction of RORα expression results in reduced expression of these genes associated with the disorder leading to the disease.¹⁶ Independently, Devanna and Vernes demonstrated that miR-137, a microRNA implicated in neuropsychiatric disorders, targets a number of genes associated with autism spectrum disorder including RORA.¹⁷ There are also additional links between RORα and autism. Deficiency of Purkinje cells is one of the most consistently identified neuroanatomical abnormalities in brains from autistic individuals^18,19 and RORα is critical in development of the Purkinje cells.²⁰⁻²³ Significant circadian disruptions have also been recognized in autistic patients,²⁴⁻²⁷ and RORs play a critical role in regulation of the circadian rhythm.^7,28 Additionally, the staggerer mouse displays behaviors that are associated with autism including abnormal spatial learning, reduced exploration, limited maze patrolling, and perseverative behavior relative to wt mice.²⁹⁻³³

SR1078 is a relatively low potency compound with limited RORα efficacy (3–5 μM EC₅₀E_max ∼ 40%),⁸ but the efficacy compares favorably to other classes of compounds that have been optimized such as a 38% decrease in the same model induced by the mGluR5 allosteric modulator GRN-529⁴⁹ and a 47% reduction by the mGluR5 antagonist MPEP.⁴⁵ Both of these compounds have been optimized and display high potency (single digit nanomolar range at mGluR5) and strong efficacy.^53,54 Thus, we believe that focused optimization of RORα ligands will provide compounds that will have improved efficacy in this model. It should also be noted that SR1078 has both RORα and RORγ agonist activity⁸ and a RORα selective agonist has not yet been developed. Thus, it is possible that the RORγ activity of this compound may also play a role in its efficacy in this model of autism. In summary, we have demonstrated that a synthetic RORα/γ agonist is able to increase the expression of key genes whose decrease in expression is associated with ASD both in cell culture and in vivo. Furthermore, the agonist decreases repetitive behavior in an animal model of autism suggesting that it is possible that ROR agonists may hold utility in treatment ASD. 

Regulation of p53 Stability and Apoptosis by a ROR Agonist

Activation of p53 function leading to cell-cycle arrest and/or apoptosis is a promising strategy for development of anti-cancer therapeutic agents. Here, we describe a novel mechanism for stabilization of p53 protein expression via activation of the orphan nuclear receptor, RORα. We demonstrate that treatment of cancer cells with a newly described synthetic ROR agonist, SR1078, leads to p53 stabilization and induction of apoptosis. These data suggest that synthetic ROR agonists may hold utility in the treatment of cancer.  

Levels of Bcl-2 and P53 Are Altered in Superior Frontal and Cerebellar Cortices of Autistic Subjects 

Results showed that levels of Bcl-2 decreased by 38% and 36% in autistic superior frontal and cerebellar cortices, respectively when compared to control tissues. By the same token, levels of P53 increased by 67.5% and 38% in the same brain areas in autistic subjects vs. controls respectively. Calculations of ratios of Bcl-2/P53 values also decreased by 75% and 43% in autistic frontal and cerebellar cortices vs. controls respectively. The autistic cerebellar values were significantly reduced (p < 0.08) vs. control only. There were no significant differences in levels of β-actin between the two groups. Additionally, there were no correlations between Bcl-2, P53, and β-actin concentrations vs. age or PMI in either group.

These results confirm and extend previous data that levels of Bcl-2 and P53 are altered in three important brain tissues, i.e. frontal, parietal, and cerebellar cortices of autistic subjects, alluding to deranged apoptotic mechanisms in autism.  

Conclusion

Increasing PTEN and Bcl-2 is already part of my Polypill, via the use of Atorvastatin.

There are of course many other genes miss-expressed in autism and we cannot give a drug for each one. We need to identify a handful of nexus, where multiple anomalies can be resolved with a single intervention.

It is good that Thomas Burris, the lead researcher, has been working on SR1078 for at least 6 years, let’s hope he continues to persevere.

I think it highly likely that some types of autism will need the opposite therapy, a RORα antagonist.

My method of attempting to modulate RORα will be different. I come back to my earlier gross simplification of autism :- 

As we have seen in earlier posts, the hormonal dysfunction, this time the balance between testosterone and estradiol, has a direct effect on RORα (and vice versa).

The schematic illustrates a mechanism through which the observed reduction in RORA in autistic brain may lead to increased testosterone levels through downregulation of aromatase. Through AR, testosterone negatively modulates RORA, whereas estrogen upregulates RORA through ER.

androgen receptor = AR 

estrogen receptor = ER

As you might know, many hormones are interrelated, so what are thought of as male/female sex hormones have much wider effects. They impact growth hormones and play a big role in calcium metabolism. They also affect serotonin.

We know that in most autism aromatase is reduced, estradiol is reduced and that there is reduced expression of estrogen receptor beta.

In the ideal world it might indeed be best to use an agonist or antagonist to fine tune RORα.

We have a chicken and the egg situation. Is RORα out of tune in autism because the hormones are disturbed, or vice versa?

We do know that hormones generally have feedback loops, but we also know that increasing a hormone like estradiol via obesity is not fully matched by a corresponding reduction in aromatase. So it looks highly plausible that you can tune RORα via estradiol, and that this could be a long term strategy, not just a short term strategy.

In the case of people with low T3 thyroid hormone centrally (in the brain), giving exogenous T3 may help initially, but in the long term it does not because feedback loops to the thyroid will reduce production of the pro-hormone T4. In the extreme you will make the thyroid gland shut down, this does happen to people using thyroid hormones for depression and even weight loss. 

T3 is quite commonly prescribed by alternative practitioners in the US for autism and also for depression in older people. In Europe this hormone is rarely even available. 

Many phytoestrogens are used as OTC autism therapies. These are dietary estrogens that are structurally similar to the human hormone estradiol and so produce estrogen-like effects. They include soy products, fenugreek, kudzu, EGCG etc.

Estradiol/Aromatase Deficiency in Autism, Schizophrenia and Bipolar

There was a rather complicated post in which I was linking some of the odd biological features of autism to something called RORα.

This was one of those posts that appeals to the scientist readers like Tyler.

The Purkinje-RORa-Estradiol-Neuroligin-KCC2 axis in Autism

Happy with his elevated estradiol level

Today’s post is more like the Psychiatrist's take on the same subject, so it is less complicated.

I was thinking that a logical way to treat boys, post puberty, and girls with autism would be to target RORα. In males this would be the treating aromatase deficiency.  You would start by measuring by measuring the level of testosterone and estradiol in both boys and girls.

My assumption is that there will be a substantial group of males who will have high testosterone and low estradiol.  In autism and its big brothers (and sisters) Schizophrenia and Bipolar, there are disturbed levels of these hormones.  One logical therapy would be estradiol, which is much less problematic for girls than boys.

Boys with genetically caused aromatase deficiency lack the female hormone estradiol, but are not treated with transdermal estradiol until after puberty.  Girls are treated with estradiol from a younger age.

Untreated males with aromatase deficiency have retarded bone age, but end up as very tall adults. They also have a problem with low bone density and so have weak bones.

Clinical Features of Aromatase Deficiency

	Female	Male
Fetal life:	Masculinization of the mother during pregnancy	Masculinization of the mother during pregnancy
Genitalia at birth:	Severe clitoromegaly and posterior labioscrotal fusion	Normal male
Childhood:	Multi-cystic ovaries	Unremarkable
Puberty:	Absent growth spurt Absent breast development Primary amenorrhea Further enlargement of clitoris Enlarged cystic ovaries Normal development of pubic and axillary hair	Absent growth spurt Normal pubertal development
Adult:	Severe estrogen deficiency Virilization Enlarged cystic ovaries Continued linear bone growth	Tall, eunucoid proportions with continued linear growth into adulthood Osteoporosis Genu valgum

Source: AROMATASE DEFICIENCY

I have commented before that I think retarded bone age is a useful marker of some types of autism. You just need an X-ray of your hand and some interpretation that looks at the gaps between the small bones.

We have also seen in the comments section of this blog that numerous readers have low bone density problems in their families.

Extreme aromatase deficiency is very rare and is caused by mutations in the CYP19A1 gene.

We saw that RORα seems to be a hub for where things go wrong in autism (also schizophrenia and bipolar); I am not suggesting a problem with the CYP19A1 gene.

One approach in psychiatry research is to just try things, without bothering too much about the underlying science.  This has been the case with Estradiol, where there have been several very positive studies in schizophrenia and bipolar.  

Estradiol in Clinical Trials

Nobody is going get approval to use Estradiol in young boys, other than those who are promoting gender reassignment. These people want to chemically block puberty and then use high doses of estradiol to feminize the male body.

Estradiol is widely used in post-menopausal women, but also in clinical trials of middle aged women with schizophrenia or bipolar, where it appears to provide a clear improvement.

Estradiol for treatment-resistant schizophrenia: a large-scale randomized-controlled trial in women of child-bearing age.

Many women with schizophrenia remain symptomatic despite optimal use of current therapies. While previous studies suggest that adjunctive oestrogen therapy might be effective, large-scale clinical trials are required before clinical applications are possible. This study is the first large-scale randomized-controlled trial in women with treatment-resistant schizophrenia. This Definitive Oestrogen Patch Trial was an 8-week, three-arm, double-blind, randomized-controlled trial conducted between 2006 and 2011. The 183 female participants were aged between 18 and 45 (mean = 35 years), with schizophrenia or schizoaffective disorder and ongoing symptoms of psychosis (Positive and Negative Syndrome Scale, PANSS score>60) despite a stable dose of antipsychotic medication for at least 4 weeks. Mean duration of illness was more than 10 years. Participants received transdermal estradiol 200 μg, transdermal estradiol 100 μg or an identical placebo patch. For the 180 women who completed the study, the a priori outcome measure was the change in PANSS score measured at baseline and days 7, 14, 28 and 56. Cognition was assessed at baseline and day 56 using the Repeatable Battery of Neuropsychological Status. Data were analysed using latent growth curve modelling. Both estradiol groups had greater decreases in PANSS positive, general and total symptoms compared with the placebo this study shows estradiol is an effective and clinically significant adjunctive therapy for women with treatment-resistant schizophrenia, particularly for positive symptoms.

A Role for Estrogen in Schizophrenia: Clinical and Preclinical Findings

The role of estrogen in bipolar disorder, a review.

BACKGROUND:

It appears that the female reproductive events and hormonal treatments may impact the course of bipolar disorder in women. In particular, childbirth is known to be associated with onset of affective episodes in women with bipolar disorder. During the female reproductive events the sex hormones, e.g. estrogen, are fluctuating and particularly postpartum there is a steep fall in the levels of serum estrogen. The role of estrogen in women with bipolar disorder is, however, not fully understood.

AIM:

The main objective of this review is to evaluate the possible relation between serum estrogen levels and women with bipolar disorder including studies of the anti-manic effects of the selective estrogen receptor modulator tamoxifen.

METHOD:

A systematically literature search on PubMed was conducted: two studies regarding the connection between serum estrogen levels and women with bipolar disorder were identified. Furthermore, four studies were found concerning the antimanic effects of tamoxifen.

RESULTS:

Both studies in the estrogen studies showed very low levels of estrogen in women with postpartum psychosis and significant improvement of symptoms after treatment with estrogen. The four tamoxifen studies found that tamoxifen was effective in producing antimanic effects.

CONCLUSION:

These results indicate that estrogen fluctuations may be an important factor in the etiology of bipolar disorder and it is obvious that more research on this topic is needed to clarify the role of estrogen in women with bipolar disorder.

Men also need to have a certain level of estradiol, but as they age, and particularly if they get overweight, they often end up with too much.  So the usual problem is too much estradiol.

In males, estrogen is produced in fat (adipose) tissue by the action of the enzyme aromatase on testosterone.  So it would not be surprising if males with five times more adipose tissue produced more estrogen/estradiol. This would might explain mild feminization of the body and the lack of more aggressive male behaviors.

Many males with schizophrenia and a substantial number with autism are on medication that causes weight gain. While there are is research on how to reduce this weight gain, if the weight gain causes more estradiol, there actually is some potential benefit.

Estrogen Plays Key Role in Male Brain Development

Male Brains Need Estrogen for Good Memory

"We found that testosterone alone can improve an aspect of memory known as spatial memory -- the kind of memory needed to drive, get dressed, use a knife and fork -- what you need to learn to navigate three-dimensional space," Asthana says. "But men with both testosterone and estrogen had better verbal memory."

Asthana thinks that new estrogen-like drugs that lack sex-hormone effects such as breast enlargement might be useful to preserve memory in aging men. He says he is planning to test this theory in human trials

An estrogen-like drug, raloxifene, was trialed unsuccessfully in women with Alzheimer’s, but not in men.

Estradiol is a research therapy for males with prostate cancer.

Estradiol in Autism

We saw in the science heavy earlier post that that children with autism do not have sufficient estrogen receptor beta expression to mediate the protective benefits of estrogen.

Estrogen receptor beta agonists, which are already known to improve brain plasticity and memory in animals, have been proposed to help reverse autism's behavioral deficits.

High testosterone, low aromatase and correspondingly low estradiol are features of autism and will compound the effect of reduced estrogen receptor beta expression.

Conclusion

There are far less issues with the use of estradiol in females with autism.  Given there have already been trials in Schizophrenia and Bipolar on females using estradiol, it is about time a psychiatrist made a trial in autism.

I think that via the effect on RORα, there will be numerous positive effects.  The risks and side effects will be exactly the same as in the previous Schizophrenia and Bipolar trials.

Having seen what, if any, positive effects the females with autism experience, it would be time to consider adult males.  Is there a behavioral benefit in small enough doses of estradiol that do not cause feminization?

It would also be useful to measure the level of estradiol in overweight males to get some benchmarks of what is “normal" today in males.

Later on, using bone-age and indeed estradiol levels it might be possible to identify a sub-group of autism who might be likely to benefit from this therapy.  There may even be familial markers, like problems associated with low bone density, which might predispose the person with autism to have low levels of estradiol.

The other issue is the lack of estrogen beta-type receptors in people with autism.

The Purkinje-RORa-Estradiol-Neuroligin-KCC2 axis in Autism

Add testosterone/estradiol to those dysfunctional hormones

This blog is about noticing connections and making things a little simpler to understand.  Today’s post is going to be a good example; all those odd sounding things like Purkinje cells and neuroligins all fitting nicely together.

Today we see how a central hormonal dysfunction (testosterone/estradiol) can lead to an ion channel dysfunction (NKCC1/KCC2) at one end of the chain and at the other explains the absence of many Purkinje cells in the autistic cerebellum, which leads to some of the observed features of autism.

I am calling it the Purkinje-RORa-Estradiol-Neuroligin-KCC2 axis, or Purkinje-KCC2 axis for short.

We also get to see how melatonin fits in here and see why disturbed sleeping patterns should be expected in someone affected by the Purkinje- KCC2 axis.

I should point out that not everyone with autism is likely affected by the Purkinje-NKCC1 axis, but I think it will apply to a majority of those with non-regressive, multigenic, strictly defined autism (SDA).

We saw in a recent post how the enzyme aromatase acts in the so-called  testosterone – estradiol shunt.

I suggested that lack of aromatase was leading to too little estradiol which then affected neuroligin 2 (NL2) which then caused down-regulation of the KCC2 cotransporter that takes chloride out of neurons. This then caused neurons to remain in a permanent immature state.

Digging a little deeper we find recent research that shows how the control loops that balance aromatase act through RORA/RORα, RORa  (retinoic acid-related orphan receptor alpha.

Source:-  http://dx.doi.org/10.1371/journal.pone.0017116.g005

The schematic illustrates a mechanism through which the observed reduction in RORA in autistic brain may lead to increased testosterone levels through downregulation of aromatase. Through AR, testosterone negatively modulates RORA, whereas estrogen upregulates RORA through ER.

androgen receptor = AR

estrogen receptor = ER

RORα (retinoic acid-related orphan receptor alpha.)

RORα certainly has a long full name. Retinoic acid is a metabolite of vitamin A (retinol).

RORα does some clever things.

RORα is necessary for normal circadian rhythms

ROR-alpha is expressed in a variety of cell types and is involved in regulating several aspects of development, inflammatory responses, and lymphocyte development

RORα is involved in processes that regulate metabolism, development, immunity, and circadian rhythm and so shows potential as drug targets. Synthetic ligands have a variety of potential therapeutic uses, and can be used to treat diseases such as diabetes, atherosclerosis, autoimmunity, and cancer. T0901317 and SR1001, two synthetic ligands, have been found to be RORα and RORγ inverse agonists that suppress reporter activity and have been shown to delay onset and clinical severity of multiple sclerosis and other Th17 cell-mediated autoimmune diseases. SR1078 has been discovered as a RORα and RORγ agonist that increases the expression of G6PC and FGF21, yielding the therapeutic potential to treat obesity and diabetes as well as cancer of the breast, ovaries, and prostate. SR3335 has also been discovered as a RORα inverse agonist.

RORs are also called nuclear melatonin receptors. Many people with autism take melatonin to balance circadian rhythms and fall asleep.

The reduced estrogen levels in women during menopause likely caused them not to sleep due to the effect on RORα.

So it would appear that some of what is good for menopausal women may actually be helpful for some people with autism.

Many Genes affected by RORα

Study uncovers molecular targets of autism-linked RORA gene

Most exciting, the researchers say, is that 426 of RORA’s gene targets are listed in AutismKB, a database of autism candidates maintained by scientists at Peking University in Beijing, and 49 in SFARI Gene.

Therapeutic Effect of a Synthetic RORα/γ Agonist in an Animal Model of Autism

Therapeutic Effect of a Synthetic RORα/γ Agonist in an Animal Model of Autism

Autism is a developmental disorder of the nervous system associated with impaired social communication and interactions as well excessive repetitive behaviors. There are no drug therapies that directly target the pathology of this disease. The retinoic acid receptor-related orphan receptor α (RORα) is a nuclear receptor that has been demonstrated to have reduced expression in many individuals with autism spectrum disorder (ASD). Several genes that have been shown to be downregulated in individuals with ASD have also been identified as putative RORα target genes. Utilizing a synthetic RORα/γ agonist, SR1078, that we identified previously, we demonstrate that treatment of BTBR mice (a model of autism) with SR1078 results in reduced repetitive behavior. Furthermore, these mice display increased expression of ASD-associated RORα target genes in both the brains of the BTBR mice and in a human neuroblastoma cell line treated with SR1078. These data suggest that pharmacological activation of RORα may be a method for treatment of autism.

For those who like natural substances, some research from Japan.

Isoflavones enhance interleukin-17 gene expression via retinoic acid receptor-related orphan receptors α and γ.

            Abstract

The retinoic acid receptor-related orphan receptors α and γ (RORα and RORγ), are key regulators of helper T (Th)17 cell differentiation, which is involved in the innate immune system and autoimmune disorders. In this study, we investigated the effects of isoflavones on RORα/γ activity and the gene expression of interleukin (IL)-17, which mediates the function of Th17 cells. In doxycycline-inducible CHO stable cell lines, we found that four isoflavones, biochanin A (BA), genistein, formononetin, and daidzein, enhanced RORα- or RORγ-mediated transcriptional activity in a dose-dependent manner. In an activation assay of the Il17a promoter using Jurkat cells, these compounds enhanced the RORα- or RORγ-mediated activation of the Il17a promoter at concentrations of 1 × 10(-6)M to 1 × 10(-5)M. In mammalian two-hybrid assays, the four isoflavones enhanced the interaction between the RORα- or RORγ-ligand binding domain and the co-activator LXXLL peptide in a dose-dependent manner. In addition, these isoflavones potently enhanced Il17a mRNA expression in mouse T lymphoma EL4 cells treated with phorbol myristate acetate and ionomycin, but showed slight enhancement of Il17a gene expression in RORα/γ-knockdown EL4 cells. Immunoprecipitation and immunoblotting assays also revealed that BA enhanced the interaction between RORγt and SRC-1, which is a co-activator for nuclear receptors. Taken together, these results suggest that the isoflavones have the ability to enhance IL-17 gene expression by stabilizing the interactions between RORα/γ and co-activators. This also provides the first evidence that dietary chemicals can enhance IL-17 gene expression in immune cells.

Genistein is a common supplement.  It is a pytoestrogen and unfortunately these substances lack potency in real life.  In test tubes they have interesting properties, but they are poorly absorbed when taken orally and so unless they are modified they are likely to have no effect in the usual tiny doses used in supplements.

This is true with very many products sold as supplements.

Sometimes care is taken to improve bioavailability as with some expensive curcumin supplements, like Longvida.

Trehalose, a supplement referred to recently in comments on this blog, is another interesting natural substance that lacks bioavailablity.  Analogs of this natural substance have been produced that are much better absorbed and are now potential drugs.

Lentztrehalose A, B, C

Purkinje Cells

Back in 2013 I wrote a post about Purkinje cells.

          Pep up those Purkinje cells

Loss of Purkinje cells is one of the few non-disputed abnormalities in autism. 

These cells are some of the largest neurons in the human with an intricately elaborate dendritic arbor, characterized by a large number of dendritic spines. Purkinje cells are found within the Purkinje layer in the cerebellum. Purkinje cells are aligned like dominos stacked one in front of the other. Their large dendritic arbors form nearly two-dimensional layers through which parallel fibers from the deeper-layers pass. These parallel fibers make relatively weaker excitatory (glutamatergic) synapses to spines in the Purkinje cell dendrite, whereas climbing fibers originating from the inferior olivary nucleus in the medulla provide very powerful excitatory input to the proximal dendrites and cell soma. Parallel fibers pass orthogonally through the Purkinje neuron's dendritic arbor, with up to 200,000 parallel fibers^[2] forming a Granule-cell-Purkinje-cell synapse with a single Purkinje cell. Each Purkinje cell receives ca 500 climbing fiber synapses, all originating from a single climbing fiber.^[3] Both basket and stellate cells (found in the cerebellar molecular layer) provide inhibitory (GABAergic) input to the Purkinje cell, with basket cells synapsing on the Purkinje cell axon initial segment and stellate cells onto the dendrites.

Purkinje cells send inhibitory projections to the deep cerebellar nuclei, and constitute the sole output of all motor coordination in the cerebellar cortex.

In humans, Purkinje cells can be harmed by a variety causes: toxic exposure, e.g. to alcohol or lithium; autoimmune diseases; genetic mutations causing spinocerebellar ataxias, Unverricht-Lundborg disease, or autism; and neurodegenerative diseases that are not known to have a genetic basis, such as the cerebellar type of multiple system atrophy or sporadic ataxias.

Purkinje cells are some of the largest neurons in the human brain and the most important.

Neuronal maturation during development is a multistep process regulated by transcription factors. The transcription factor RORα (retinoic acid-related orphan receptor α) is necessary for early Purkinje cell maturation but is also expressed throughout adulthood.

The active form (T₃) of thyroid hormone  controls critical aspects of cerebellar development, such as migration of postmitotic neurons and terminal dendritic differentiation of Purkinje cells. T₃ action on the early Purkinje cell dendritic differentiation process is mediated by RORα.

In autism we have seen that oxidative stress may lead to low levels of T₃ in the autistic brain.  We now see that low levels of RORα are also likely in autsim.

The combined effect would help explain the loss of Purkinje cells in autism.

Induction of early Purkinje cell dendritic differentiation by thyroid hormone requires RORα

Mature Purkinje Cells Require the Retinoic Acid-Related Orphan Receptor-α (RORα) to Maintain Climbing Fiber Mono-Innervation and Other Adult Characteristics

Regional Alterations in Purkinje Cell Density in Patients with Autism

Neuropathological studies, using a variety of techniques, have reported a decrease in Purkinje cell (PC) density in the cerebellum in autism. We have used a systematic sampling technique that significantly reduces experimenter bias and variance to estimate PC densities in the postmortem brains of eight clinically well-documented individuals with autism, and eight age- and gender-matched controls. Four cerebellar regions were analyzed: a sensorimotor area comprised of hemispheric lobules IV–VI, crus I & II of the posterior lobe, and lobule X of the flocculonodular lobe. Overall PC density was thus estimated using data from all three cerebellar lobes and was found to be lower in the cases with autism as compared to controls. These findings support the hypothesis that abnormal PC density may contribute to selected clinical features of the autism phenotype.

Estradiol – Neuroligin 2 to KCC2

We saw in a recent post how reduced levels of estradiol could lead to KCC2 underexpression via the action of neuroligin 2.

Neuroligins, Estradiol and Male Autism

Conclusion

So in my grossly oversimplified world of autism, I think I have a plausible case for the Purkinje-KCC2 axis.  I think that in addressing this axis numerous other issues would also be solved ranging from sleep issues to those hundreds of other genes whose regulation is at least partly governed by RORα.

The KCC2 end of the axis can be treated by bumetanide, diamox/acetazolamide, potassium bromide and possibly by intranasal IGF-1/insulin.  

How to address the rest of the Purkinje-KCC2 axis?

·        More RORα, or just a RORα agonist.

·        More aromatase

·        Genistein may help, but you would need it by the bucket load, due to bioavailability issues

·        Estrogen receptor agonists

·        Exogenous estradiol

The simplest is the last one and really should be trialed on adult males with autism.  The dose would need to be much lower than the feminizing dose, so 0.2mg would seem a good starting dose for such a study.

Due to the feedback loops somethings may work short term, but not long term.