Developing a Treatment for ASD

Despite the high prevalence of Autism Spectrum Disorder (ASD), there are no FDA-approved medications for the core symptoms. Furthermore, many of the medications used to treat secondary symptoms of ASD come with significant side effects.1There is emerging evidence that abnormal Nitric Oxide signaling, and the subsequent cellular stress are linked to ASD and may drive the associated symptoms. 2-6Therefore, we aim to target Nitric Oxide signaling in the brain to develop a novel treatment for the core symptoms of ASD. 

The Role of Nitric Oxide

Nitric Oxide (NO) is a neurotransmitter and key signaling molecule in the brain that modulates physiological neuronal and synaptic functions.7,8However, aberrant signaling and high levels of Nitric Oxide can result in nitrosative stress, which leads to toxicity and disrupts the normal functioning of neurons in the brain leading to autism-like behavioral deficits.6Scientific studies have shown elevated nitrosative stress in both animal models of Autism Spectrum Disorder (ASD) and human patients.5,6,9

The Role of Nitric Oxide

Targeting NO Production in the Brain

Neuronal nitric oxide synthase (nNOS) is the enzyme responsible for Nitric Oxide production in the brain. As nNOS is found in neurons, selectively targeting this protein provides an opportunity to regulate Nitric Oxide production within the brain.

Targeting NO Production in the Brain

Our Hypothesis: Mechanism of Action

High Levels of Nitric Oxide Lead to Cellular Dysfunction in Brain

High Levels of Nitric Oxide Lead to Cellular Dysfunction in Brain NOS overactivation produces high levels of Nitric Oxide, leading to increased levels of reactive nitrogen and nitrosative stress. The result is cellular toxicity and neuronal dysfunction. 

Inhibiting nNOS to Treat ASD-Like Phenotypes

Inhibiting nNOS to Treat ASD-Like Phenotypes Inhibition of nNOS activity lowers Nitric Oxide levels and reduces nitrosative stress, rescuing neuronal abnormalities.

Our Results

Our preclinical work shows that inhibiting nNOS activity reduces nitrosative stress in the brain and reverses ASD-like phenotypes in multiple mouse and cellular models of ASD. We proved this in patients’ stem cells.6

Lowered Nitrosative Stress

Inhibition of nNOS reduced nitrosative stress and signs of aberrant NO signaling in the brain. Lowering reactive nitrogen species through nNOS inhibition can result in healthy cellular conditions.

Lowered Nitrosative Stress
Increased Number of Dendritic Spines

Dendritic spines are a structure in neurons that play a critical role in synaptic transmission and have been shown to be reduced in ASD patients. nNOS inhibition results in an increased number of dendritic spines in the brain. 

Our Results Our preclinical work shows that inhibiting nNOS activity reduces nitrosative stress in the brain and reverses ASD-like phenotypes in multiple mouse and cellular models of ASD. We proved this in patients’ stem cells.6 Lowered Nitrosative Stress Inhibition of nNOS reduced nitrosative stress and signs of aberrant NO signaling in the brain. Lowering reactive nitrogen species through nNOS inhibition can result in healthy cellular conditions. Lowered Nitrosative Stress Increased Number of Dendritic Spines
Reduced Anxiety-Like Behavior

nNOS inhibition reversed anxiety-like behavior when tested during an elevated plus maze experiment. In this test, treated mice spent more time exposed in the open arms of an elevated structured as opposed to that of untreated mice.  

anxiety mouse small
Increased Novel Object Recognition and Interest

nNOS inhibition increased the interest in novel objects over familiar one, suggesting an improvement in object memory and exploratory behaviors.  

memory
Increased Sociability

Inhibition of nNOS resulted in increased sociability and overall interaction with other mice in several preclinical models of ASD.  

Increased Sociability

nNOS Inhibition Reverses ASD-Like Behavior in Three Different ASD mouse models

Increased Novelty-Seeking and Reduced Restricted Behavior

Increased Novelty-Seeking and Reduced Restricted Behavior

Increased Sociability

Increased Sociability

Reduced Anxiety-Like Behavior

Reduced Anxiety-Like Behavior

WT (wild type mice), M (Shank3 mutant mice), M+Treatment (Shank3 mutant mice treated with an nNOS inhibitor). Data is presented as mean ± SD. Statistical significance was determined using a two-way ANOVA with Bonferroni’s multiple comparisons tests. *p<0.05, **p<0.001, ***p<0.0001, and ns=non-significant.

Our Timeline

Timeline

* Our lead compound BA102 is not the same one used in the publication. Bridging studies proving similar efficacy have been completed. *

​​References

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