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Showing posts with label Arbaclofen. Show all posts
Showing posts with label Arbaclofen. Show all posts

Tuesday 28 January 2020

Piperine/Resveratrol/Sunitinib for Rett’s and indeed much Autism? Or, R-Baclofen to raise KCC2 expression in Bumetanide-responsive autism.



Piperine/Pepper             Resveratrol/Red wine          Sunitinib/Sutent
  

This post is all about lowering chloride within neurons, by increasing the expression of the transporter that lets it leave, called KCC2.


Today’s post is one I never finished writing from last year; I looked up the price of Sutent/Sunitinib and then I remembered why. It does again highlight how cancer drugs, when they become cheap generics, will provide interesting options for autism treatment. It also shows again how Rett Syndrome is getting attention from researchers.

It also highlights that really clever Americans are looking for bumetanide alternatives, in the false belief that bumetanide has troubling side effects that cannot be managed/mitigated.

The study is by some clever guys in Cambridge Massachusetts.

Another group of clever guys from MIT burned through $40 million dollars a few years ago trying to develop R-Baclofen for Fragile-X and autism.  After that Roche-funded clinical trial failed, R-Baclofen has now been resurrected and a new trial is planned, with different end points (measures of success).

Today we see why many people should indeed respond positively to R-Baclofen, but the mode of action is entirely different to the one originally targeted by the clever guys from MIT.

Tucked away in the supplementary material of today’s paper we see that R-Baclofen increases the expression of the transporter (KCC2) that takes chloride out of neurons. So, R-Baclofen is doing the same thing as Bumetanide, just to a lesser extent and in a different way.  Both lower intracellular chloride.

That means that people responsive to bumetanide should get a further boost from R baclofen, but you might need a lot of it.

Clever they may be, but these researchers do not know how to communicate their findings.  I had to dig through the supplementary tables to extract the good stuff, which is a list of what substances increase KCC2 in regular brains (Table S1) and specifically in Rett Syndrome brains (Table S2).

This blog does rather bang on about blocking/inhibiting NKCC1 that lets chloride into neurons, you can of course alternatively open up KCC2 to let the chloride flood out. This latter strategy is proposed by the MIT researchers.

What really matters is the ratio KCC2/NKCC1.  In people with bumetanide-responsive autism, which pretty clearly will include girls with Rett Syndrome, you want to increase KCC2/NKCC1. So, block/down-regulate NKCC1 and/or up-regulate KCC2.

·        NKCC1

·        KCC2


The researchers identified 14 compounds.  To be useful as drugs these compounds have to be able to cross the blood brain barrier to be of much use, many do not.

In the paper they call KCC2 expression-enhancing compounds KEECs.

We have five approved drugs to add to the list that are functionally the same to primary hit compounds. 

·        Sunitinib
·        Crenolanib
·        Indirubin Monoxiome
·        Cabozantinib
·        TWS-119


The researchers went on to test just two compounds in Rett syndrome mice; they picked piperine (from black pepper) and KW 2449 (a leukemia drug)


Even R-baclofen pops up, with a “B score” of 6.65 (needs to be >3 to increase KCC2 expression).



Abstract
Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the methyl CpG binding protein 2 (MECP2) gene. There are currently no approved treatments for RTT. The expression of K+/Cl- cotransporter 2 (KCC2), a neuron-specific protein, has been found to be reduced in human RTT neurons and in RTT mouse models, suggesting that KCC2 might play a role in the pathophysiology of RTT. To develop neuron-based high-throughput screening (HTS) assays to identify chemical compounds that enhance the expression of the KCC2 gene, we report the generation of a robust high-throughput drug screening platform that allows for the rapid assessment of KCC2 gene expression in genome-edited human reporter neurons. From an unbiased screen of more than 900 small-molecule chemicals, we have identified a group of compounds that enhance KCC2 expression termed KCC2 expression-enhancing compounds (KEECs). The identified KEECs include U.S. Food and Drug Administration-approved drugs that are inhibitors of the fms-like tyrosine kinase 3 (FLT3) or glycogen synthase kinase 3β (GSK3β) pathways and activators of the sirtuin 1 (SIRT1) and transient receptor potential cation channel subfamily V member 1 (TRPV1) pathways. Treatment with hit compounds increased KCC2 expression in human wild-type (WT) and isogenic MECP2 mutant RTT neurons, and rescued electrophysiological and morphological abnormalities of RTT neurons. Injection of KEEC KW-2449 or piperine in Mecp2 mutant mice ameliorated disease-associated respiratory and locomotion phenotypes. The small-molecule compounds described in our study may have therapeutic effects not only in RTT but also in other neurological disorders involving dysregulation of KCC2.





Table S1. KEECs identified from screening with WT human KCC2 reporter neurons.






Table S2. KEECs identified from screening with RTT human KCC2 reporter neurons


Note Baclofen, Quercetin, Luteolin etc

















Fig. 3. Identification of KEECs that increase KCC2 expression in human RTT neurons
B score >3 indicates compounds potentially increasing KCC2 expression

In cultured RTT neurons, treatment with KEECs KW-2449 and BIO restored the impaired KCC2 expression and rescued deficits in both GABAergic and glutamatergic neurotransmissions, as well as abnormal neuronal morphology. Previous data suggested that disrupted Cl− homeostasis in the brainstem causes abnormalities in breathing pattern (64), consistent with breathing abnormalities seen in mice carrying a conditional Mecp2 deletion in GABAergic neurons (67). The reduction in locomotion activity observed in the Mecp2 mutant mice has also been attributed to abnormalities in the GABAergic system (65). Therefore, treatment with the KEEC KW-2449 or piperine may ameliorate disease phenotypes in MeCP2 mutant mice through restoration of the impaired KCC2 expression and GABAergic inhibition.

Most KEECs that enhanced KCC2 expression in WT neurons, including KW-2449, BIO, and resveratrol, also induced a robust increase of KCC2 reporter activity in RTT neurons (Fig. 3, A and B; a complete list of hit compounds is provided in table S2). The increase in KCC2 signal induced by KEECs was higher in RTT neurons than in WT neurons,


Our results establish a causal relationship between reduced FLT3 or GSK3 signaling activity and increased KCC2 expression.

Two hit compounds, resveratrol and piperine, act on different pathways than the kinase inhibitors, activating the SIRT1 signaling pathway (50) and the TRPV1 (51), respectively

Thus, our data demonstrate that activation of the SIRT1 pathway or the TRPV1 channel enhances KCC2 expression in RTT human neurons.


The group of KEECs reported here may help to elucidate the molecular mechanisms that regulate KCC2 gene expression in neurons. A previous study conducted with a glioma cell line showed that resveratrol activates the SIRT1 pathway and reduces the expression of NRSF/REST (50), a transcription factor that suppresses KCC2 expression (52). Our results demonstrate that resveratrol increases KCC2 expression by a similar mechanism, which could contribute to the therapeutic benefit of resveratrol on a number of brain disease conditions (68, 69). We also identified a group of GSK3 pathway inhibitors as KEECs. Overactivation of the GSK3 pathway has been reported in a number of brain diseases (70). Thus, our results suggest that GSK3 pathway inhibitors could exert beneficial effects on brain function through stimulating KCC2 expression. Another major KEEC target pathway, the FLT3 kinase signaling, has been investigated as a cancer therapy target (71, 72). Although FLT3 is expressed in the brain (73), drugs that target FLT3 pathway have not been extensively studied as potential treatments for brain diseases. Our results provide the first evidence that FLT3 signaling in the brain is critical for the regulation of key neuronal genes such as KCC2. Therefore, this work lays the foundation for further research to repurpose a number of clinically approved FLT3 inhibitors as novel brain disease therapies

Our results are valuable for the development of novel therapeutic strategies to treat neurodevelopmental diseases through rectification of dysfunctional neuronal chloride homeostasis. Because of the lack of pharmaceutical reagents that enhance KCC2 expression, bumetanide, a blocker of the inward chloride transporter NKCC1 that counteracts KCC2, has been used as an alternative (74). Bumetanide treatment has shown benefits in treating symptoms in mouse models of fragile X syndrome (75) and Down’s syndrome (76) and was shown to confer symptomatic benefit to human patients with autism or fragile X syndrome (77, 78). These findings strongly suggest that pharmacological restoration of disrupted chloride homeostasis may provide symptomatic treatment for various neurodevelopmental and neuropsychiatric disorders. However, NKCC1 lacks the neuron- restricted expression pattern of KCC2 and is also expressed in nonbrain tissue including kidney and inner ears (79), consistent with knockout of Nkcc1 in mouse model leading to deafness and imbalance (30). Therefore, bumetanide treatment may trigger undesirable side effects, thus severely limiting its therapeutic application. In contrast, the expression of KCC2 is restricted to neurons, and a number of the KEECs identified in this study that enhance KCC2 expression in neurons are Food and Drug Administration–approved and have not elicited any severe adverse effects in clinical trials (80–83). The promising efficacy of KEECs demonstrated in this study and the known safety of the KCC2 target warrant further preclinical and clinical studies to investigate these drugs and their derivatives as potential therapies for neurodevelopmental diseases.

In summary, in this work, we investigated the efficacy of KEECs to rescue a number of well-documented cellular and behavior phenotypes of RTT, including impaired GABA functional switch, reductions in excitatory synapse number and strength, immature neuronal morphology (53, 54), as well as an increase in breathing pauses and a decrease in locomotion (84). It is possible, however, that KEECs may also be effective in treatment of conditions other than RTT, as impairment in KCC2 expression has been linked to many brain diseases (17, 85) including epilepsy (86–88), schizophrenia (19, 20, 89), brain and spinal cord injury (21, 90), stroke and ammonia toxicity conditions (91–93), as well as the impairments in learning and memory observed in the senile brain (23). Thus, a phenotypically diverse array of brain diseases may benefit from enhancing the expression of KCC2. The newly identified KEECs are potential therapeutic agents for otherwise elusive neurological disorders



Rett syndrome (RTT) is a neurodevelopmental disorder caused by mutations in the methyl CpG binding protein 2 (MECP2) gene. There are currently no approved treatments for RTT. The expression of K+/Cl− cotransporter 2 (KCC2), a neuron-specific protein, has been found to be reduced in human RTT neurons and in RTT mouse models, suggesting that KCC2 might play a role in the pathophysiology of RTT. To develop neuron-based high-throughput screening (HTS) assays to identify chemical compounds that enhance the expression of the KCC2 gene, we report the generation of a robust high-throughput drug screening platform that allows for the rapid assessment of KCC2 gene expression in genome-edited human reporter neurons. From an unbiased screen of more than 900 small-molecule chemicals, we have identified a group of compounds that enhance KCC2 expression termed KCC2 expression– enhancing compounds (KEECs). The identified KEECs include U.S. Food and Drug Administration–approved drugs that are inhibitors of the fms-like tyrosine kinase 3 (FLT3) or glycogen synthase kinase 3 (GSK3) pathways and activators of the sirtuin 1 (SIRT1) and transient receptor potential cation channel subfamily V member 1 (TRPV1) pathways. Treatment with hit compounds increased KCC2 expression in human wild-type (WT) and isogenic MECP2 mutant RTT neurons, and rescued electrophysiological and morphological abnormalities of RTT neurons. Injection of KEEC KW-2449 or piperine in Mecp2 mutant mice ameliorated disease-associated respiratory and locomotion phenotypes. The small-molecule compounds described in our study may have therapeutic effects not only in RTT but also in other neurological disorders involving dysregulation of KCC2.


By screening these KCC2 reporter human neurons, we identified a number of hits KCC2 expression–enhancing compounds (KEECs) from ~900 small-molecule compounds. Identified KEECs were validated by Western blot and quantitative reverse transcription polymerase chain reaction (RT-PCR) experiments on cultured human wild-type (WT) and isogenic RTT neurons, as well as on organotypic mouse brain slices. Pharmacological and molecular biology experiments showed that identified KEECs act through inhibition of the fms-like tyrosine kinase 3 (FLT3) or glycogen synthase kinase 3b (GSK3b) kinases, or activation of the sirtuin 1 (SIRT1) or transient receptor potential cation channel subfamily V member 1 (TRPV1) pathways. Treatment of RTT neurons with KEECs rescued disease-related deficits in GABA functional switch, excitatory synapses, and neuronal morphological development. Last, injection of the identified KEEC KW-2449 or piperine into a Mecp2 mutant mice ameliorated behavioral phenotypes including breathing pauses and reduced locomotion, which represent important preclinical data, suggesting that the KEECs identified in this study may be effective in restoring impaired E/I balance in the RTT brain and provide symptomatic treatment for patients with RTT.





Fig. 2. KEEC treatment–induced enhancement of KCC2 protein and mRNA expression in cultured organotypic mouse brain slices and a hyperpolarizing EGABA shift in cultured immature neurons.

(E to G) KCC2 and NKCC1 mRNA expression induced by FLT3 inhibitors including sunitinib (n = 4), XL-184 (n = 6), crenolanib (n = 4), or a structural analog of BIO termed indirubin monoxime (n = 6). The calculated ratios of KCC2/NKCC1 mRNA expression are shown in (G). A.U., arbitrary units




Our results are valuable for the development of novel therapeutic strategies to treat neurodevelopmental diseases through rectification of dysfunctional neuronal chloride homeostasis. Because of the lack of pharmaceutical reagents that enhance KCC2 expression, bumetanide, a blocker of the inward chloride transporter NKCC1 that counteracts KCC2, has been used as an alternative (74). Bumetanide treatment has shown benefits in treating symptoms in mouse models of fragile X syndrome (75) and Down’s syndrome (76) and was shown to confer symptomatic benefit to human patients with autism or fragile X syndrome (77, 78). These findings strongly suggest that pharmacological restoration of disrupted chloride homeostasis may provide symptomatic treatment for various neurodevelopmental and neuropsychiatric disorders. However, NKCC1 lacks the neuron restricted expression pattern of KCC2 and is also expressed in nonbrain tissue including kidney and inner ears (79), consistent with knockout of Nkcc1 in mouse model leading to deafness and imbalance (30). Therefore, bumetanide treatment may trigger undesirable side effects, thus severely limiting its therapeutic application. In contrast, the expression of KCC2 is restricted to neurons, and a number of the KEECs identified in this study that enhance KCC2 expression in neurons are Food and Drug Administration–approved and have not elicited any severe adverse effects in clinical trials (80–83). The promising efficacy of KEECs demonstrated in this study and the known safety of the KCC2 target warrant further preclinical and clinical studies to investigate these drugs and their derivatives as potential therapies for neurodevelopmental diseases.


In summary, in this work, we investigated the efficacy of KEECs to rescue a number of well-documented cellular and behavior phenotypes of RTT, including impaired GABA functional switch, reductions in excitatory synapse number and strength, immature neuronal morphology (53, 54), as well as an increase in breathing pauses and a decrease in locomotion (84). It is possible, however, that KEECs may also be effective in treatment of conditions other than RTT, as impairment in KCC2 expression has been linked to many brain diseases (17, 85) including epilepsy (86–88), schizophrenia (19, 20, 89), brain and spinal cord injury (21, 90), stroke and ammonia toxicity conditions (91–93), as well as the impairments in learning and memory observed in the senile brain (23). Thus, a phenotypically diverse array of brain diseases may benefit from enhancing the expression of KCC2. The newly identified KEECs are potential therapeutic agents for otherwise elusive neurological disorders.




The science-light version:-

Drug screen reveals potential treatments for Rett syndrome

An experimental leukemia drug and a chemical in black pepper ease breathing and movement problems in a mouse model of Rett syndrome, according to a new study.

Rett syndrome is a rare brain condition related to autism, caused by mutations in the MECP2 gene. Because the gene is located on the X chromosome, the syndrome occurs almost exclusively in girls. No drugs are available to treat Rett.
The team screened 929 compounds from three large drug libraries, including one focused on Rett therapies. They found 30 compounds that boost KCC2’s expression in the MECP2 neurons; 14 of these also increased the protein’s expression in control neurons.

The team tested two of the identified compounds in mice with mutations in MECP2: KW-2449, which is a small molecule in clinical trials for leukemia, and piperine, an herbal supplement and component of black pepper. These mice have several traits reminiscent of Rett. They are prone to seizures, breathing problems, movement difficulties and disrupted social behavior.
Injecting the mice with either drug daily for two weeks improved the animals’ mobility relative to untreated mice. The drugs also eased the mice’s breathing problems, decreasing the frequency of pauses in breathing (apnea). The findings appeared in July in Science Translational Medicine.


 

Piperine, Resveratrol and analogs thereof

Piperine and Resveratrol are commercially available supplements.

Resveratrol has been mentioned many times in this blog.  It has numerous beneficial properties, to which we can now add increasing KCC2 expression, but it is held back by its poor ability to cross the blood barrier.

The other natural substance highlighted in the study is piperine. Piperine is the substance that gets added to curcumin to increases its bioavailability and hopefully get its health benefits.

Piperine has been recently been found to be a positive allosteric modulator of GABAA receptors.

It may be that piperine has 2 different effects on GABA, or maybe it is just the same one?

The result is that people are trying to develop modified versions of piperine that could be patentable commercial drugs.

Piperine also activated TRPV1 receptors.

You might wonder what is the effect in humans of plain old piperine in bumetanide-responsive autism.

Invitro blood–brain-barrier permeability predictions for GABAA receptor modulating piperine analogs

The alkaloid piperine from black pepper (Piper nigrum L.) and several synthetic piperine analogs were recently identified as positive allosteric modulators of γ-aminobutyric acid type A (GABAA) receptors. In order to reach their target sites of action, these compounds need to enter the brain by crossing the blood–brain barrier (BBB). We here evaluated piperine and five selected analogs (SCT-66, SCT-64, SCT-29, LAU397, and LAU399) regarding their BBB permeability. Data were obtained in three in vitro BBB models, namely a recently established human model with immortalized hBMEC cells, a human brain-like endothelial cells (BLEC) model, and a primary animal (bovine endothelial/rat astrocytes co-culture) model. For each compound, quantitative UHPLC-MS/MS methods in the range of 5.00–500 ng/mL in the corresponding matrix were developed, and permeability coefficients in the three BBB models were determined. In vitro predictions from the two human BBB models were in good agreement, while permeability data from the animal model differed to some extent, possibly due to protein binding of the screened compounds. In all three BBB models, piperine and SCT-64 displayed the highest BBB permeation potential. This was corroborated by data from in silico prediction. For the other piperine analogs (SCT-66, SCT-29, LAU397, and LAU399), BBB permeability was low to moderate in the two human BBB models, and moderate to high in the animal BBB model. Efflux ratios (ER) calculated from bidirectional permeability experiments indicated that the compounds were likely not substrates of active efflux transporters.


The alkaloid piperine, the major pungent component of black pepper (Piper nigrum L.), was recently identified as a positive allosteric γ-aminobutyric acid type A (GABAA) receptor modulator. The compound showed anxiolytic-like activity in behavioral mouse models, and was found to interact with the GABAA receptors at a binding site that was independent of the benzodiazepine binding site [1,2]. Given that the compound complied with Lipinski’s “rule of five” [1], it represented a new scaffold for the development of novel GABAA receptor modulators [1–3]. Given that piperine also activates the transient receptor potential vanilloid 1 (TRPV1) receptors [4] which are involved in pain signaling and regulation of the body temperature [5,6], structural modification of the parent compound was required to dissect GABAA and TRPV1 activating properties

For drugs acting on the central nervous system (CNS), brain penetration is required. This process is controlled by the blood-brain barrier (BBB), a tight layer of endothelial cells lining the brain capillaries that limits the passage of molecules from the blood circulation into the brain [10]. Since low BBB permeability can reduce CNS exposure [11], lead compounds should be evaluated at an early stage of the drug development process for their ability to permeate the BBB [12].

Conclusions

Piperine and five selected piperine analogs with positive GABAA receptor modulatory activity were screened in three in vitro cell-based human and animal BBB models for their ability to cross the BBB. Data from the three models differed to some extent, possibly due to protein binding of the piperine analogs. In all three models, piperine and SCT-64 displayed the highest BBB permeation potential, which could be corroborated by in silico prediction data. For the other piperine analogs (SCT-66, SCT-29, LAU397, and LAU399), BBB permeability was low to moderate in the two human models, and moderate to high in the animal model. ER calculated from bidirectional permeability experiments indicated that the compounds were likely not substrates of active efflux. In addition to the early in vitro BBB permeability assessment of the compounds, further studies (such as PK and drug metabolism studies) are currently in progress in our laboratory. Taken together, these data will serve for selecting the most promising candidate molecule for the next cycle of medicinal chemistry optimization




Conclusion

My conclusions are a little different to the MIT researchers

“The newly identified KEECs are potential therapeutic agents for otherwise elusive neurological disorders.”

This assumes that you cannot safely use bumetanide/azosemide, which you can.  Open your eyes and look at France, where several hundred children with autism are safely taking bumetanide.

”It is possible, however, that KEECs may also be effective in treatment of conditions other than RTT, as impairment in KCC2 expression has been linked to many brain diseases”

We have copious evidence that elevated chloride is a feature of many conditions, not just Rett’s and an effective cheap therapy has been sitting in the pharmacy for decades.

In the clinical trial of R-Baclofen that failed, there were some positive effects on some subjects.  Were the positive effects just caused by the effect of Baclofen in increasing KCC2 expression?

Should R-Baclofen become a cheap generic, it might indeed become a useful add-on for those with bumetanide-responsive. Regular Baclofen (Lioresal) is an approved drug, but it does have some side effects, so most likely R-baclofen will have side effects in some.

Baclofen itself in modest doses has little effect on bumetanide-responsive autism.



A cheap side-effect free KCC2 enhancer would be a good drug for autism, although cheap, safe NKCC1 blockers already exist. 

I have no idea if piperine benefits bumetanide-responsive autism.  Piperine has long been used in traditional medicine.

The TRPV1 receptor also affected by piperine plays a role in pain and anxiety.

We saw in the post below that TRPV1 controls cortical microglia activation and that GABARAP modulates TRPV1 expression.

So, TRPV1 and GABAA receptors are deeply intertwined.

  

GABAa receptor trafficking, Migraine, Pain, Light Sensitivity, Autophagy, Jacobsen Syndrome,Angelman Syndrome, GABARAP, TRPV1, PX-RICS, CaMKII and CGRP ... Oh and the"fever effect"



Is Piperine going to make autism better, or worse?








Monday 3 April 2017

Different Types of Excitatory/Inhibitory Imbalance in Autism, Fragile-X & Schizophrenia


There is much written in the complex scientific literature about the Excitatory/Inhibitory (E/I) imbalance between neurotransmitters in autism. 

Many clinical trials have already been carried out, particularly in Fragile-X.  These trials were generally ruled as failures, in spite of a significant minority who responded quite well in some of these trials.

As we saw in the recent post on the stage II trial of bumetanide in severe autism, there is so much “background noise” in the results from these trials and it is easy to ignore a small group who are responders.  I think if you have less than 40%, or so, of positive responders they likely will get lost in the data. 

You inevitably get a significant minority who appear to respond to the placebo, because people with autism usually have good and bad days and testing is very subjective.

There are numerous positive anecdotes from people who participated in these “failed” trials.  If you have a child who only ever speaks single words, but while on the trial drug starts speaking full sentences and then reverts to single words after the trial, you do have to take note. I doubt this is a coincidence.

Here are some of the trialed drugs, just in Fragile-X, that were supposed to target the E/I imbalance:-

Metabotropic glutamate receptor 5 (mGluR5) antagonist

·        Mavoglurant

·        Lithium

mGluR5 negative allosteric modulator

·        Fenobam

N-methyl-D-aspartic acid (NMDA) antagonist

·        Memantine

Glutamate re-uptake promoter

·        Riluzole

Suggested to have effects on NMDA & mGluR5 & GABAA

·        Acamprosate

GABAB agonist

·        Arbaclofen

Positive allosteric modulator (PAM) of GABAA receptor

·        Ganaxolone


Best not to be too clever

Some things you might use to modify the E/I imbalance can appear to have the opposite effect, as was highlighted in the comments in the post below:-



So whilst it is always a good idea to try and figure things out, you may end up getting things the wrong way around, mixing up hypo and hyper.

The MIT people who work on Fragile-X are really clever and they have not figured it all out.


Fragile-X and Idiopathic Autism

Fragile-X gets a great deal of attention, because its biological basis is understood.  It results in a failure to express the fragile X mental retardation protein (FMRP), which is required for normal neural development.

We saw in the recent post about eIF4E, that this could lead to an E/I imbalance and then autism.




Our reader AJ started looking at elF4E and moved on to EIF4E- binding protein number 1.

In the green and orange boxes below you can find elF4E and elF4E-BP2.

This has likely sent some readers to sleep, but for those whose child has Fragile-X, I suggest they read on, because it is exactly here that the lack of fragile X mental retardation protein (FMRP) causes a big problem.  The interaction between FMRP on the binding proteins of elF4E, cause the problem with neuroligins (NLGNs), which causes the E/I imbalance.  Look at the red oval shape labeled FMRP and green egg-shaped NLGNs.

In which case, while AJ might naturally think Ribavirin is a bit risky for idiopathic autism, it might indeed be very effective in some Fragile-X.  You would hope some researcher would investigate this.




Can you have more than one type of E/I imbalance?

Readers whose child responds well to bumetanide probably wonder if they have solved their E/I imbalance.

I think they have most likely improved just one dysfunction that fits under the umbrella term E/I imbalance.  There are likely other dysfunctions that if treated could further improve cognition and behavior.

On the side of GABA, it looks like turning up the volume on α3 sub-unit and turning down the volume on α5 may help. We await the (expensive) Down syndrome drug Basmisanil for the latter, given that the cheap 80 year old drug Cardiazol is no longer widely available. Turning up the volume on α3 sub-unit can be achieved extremely cheaply, and safely, using a tiny dose of Clonazepam.

It does appear that targeting glutamate is going to be rewarding for at least some of those who respond to bumetanide.

One agonist of NMDA receptors is aspartic acid. Our reader Tyler is a fan of L-Aspartic Acid, that is sold as a supplement that may boost athletic performance.  

Others include D-Cycloserine, already used in autism trials; also D-Serine and L-Serine.

D-Serine is synthesized in the brain from L-serine, its enantiomer, it serves as a neuromodulator by co-activating NMDA receptors, making them able to open if they then also bind glutamate. D-serine is a potent agonist at the glycine site of NMDA receptors. For the receptor to open, glutamate and either glycine or D-serine must bind to it; in addition a pore blocker must not be bound (e.g. Mg2+ or Pb2+).

D-Serine is being studied as a potential treatment for schizophrenia and L-serine is in FDA-approved human clinical trials as a possible treatment for ALS/Motor neuron disease.  

You may be thinking, my kid has autism, what has this got to do with ALS/Motor neuron disease (from the ice bucket challenge)? Well one of the Fragile-X trial drugs at the beginning of this post is Riluzole, a drug developed for specially for ALS.  Although it does not help that much in ALS, it does something potentially very useful for some autism, ADHD and schizophrenia; it clears away excess glutamate.


Fragile-X is likely quite different to many other types of autism

I suspect that within Fragile-X there are many variations in the downstream biological dysfunctions and so that even within this definable group, there may be no universal therapies.  So for some people an mGluR5 antagonist may be appropriate, but not for others.

Even within this discrete group, we come back to the need for personalized medicine.

I do not think Fragile-X is a good model for broader autism.


Glutamate Therapies

There are not so many glutamate therapies, so while the guys at MIT might disapprove, it would not be hard to apply some thoughtful trial and error.

You have:

mGluR5

     ·        mGluR5 agonists (only research compounds)

·        mGluR5 positive allosteric modulators (only research compounds)

·        mGluR5 antagonists (Mavoglurant, Lithium)

·        mGluR5 negative allosteric modulators (Fenobam, Pu-erh tea decreases mGluR5 expression )

Today you can only really treat too much mGluR5 activity.  It there is too little activity, the required drugs are not yet available.  I wonder how many people with Fragile-X are drinking Pu-erh tea, it is widely available.


NMDA agonists

D-Cycloserine an antibiotic with similar structure to D-Alanine (D-Cycloserine was trialed in autism and schizophrenia)

ɑ-amino acids:

·         Aspartic acid (trialed and used  by Tyler, suggested for schizophrenia)

·         D-Serine (trialed in schizophrenia)




NMDA antagonists


·        Memantine (widely used off-label in autism, but failed in clinical trials)


·        Ketamine (trialed intra-nasal in autism)


Glutamate re-uptake promoters via GLT-1


·        Riluzole


·        Bromocriptine


·        Beta-lactam antibiotics