Altered Gut Microbial Diversity and Depletion of SCFA-Producing Taxa Associated with ASD-like Phenotypes in a Prenatal VPA Rat Model.

This animal study found that rats exposed to valproic acid before birth developed autism-like behaviors and gut problems. The rats showed social difficulties, repetitive behaviors, and memory issues. Their gut bacteria were unhealthy, with fewer 'good' bacteria that normally help brain function. The researchers found brain inflammation and stress that may be linked to the gut problems, suggesting gut health might influence autism-like behaviors.

This preclinical study investigated how prenatal valproic acid (VPA) exposure, a known autism risk factor, affects gut-brain interactions in rats. VPA-exposed offspring displayed autism-like behaviors including social deficits, repetitive behaviors, and memory impairments. Gut microbiota analysis revealed reduced diversity and depletion of beneficial bacteria that produce short-chain fatty acids (SCFAs), particularly Clostridia and Lachnospiraceae families. The study identified increased harmful bacteria (Bacteroidia, Enterobacteriaceae) alongside brain inflammation and oxidative stress markers.

Multivariate analyses demonstrated connections between gut dysbiosis and behavioral impairments, suggesting the gut-brain axis plays a mechanistic role in autism-like phenotypes following prenatal environmental insults.

Findings suggest gut microbiota modulation and SCFA supplementation as potential therapeutic approaches for autism. Highlights importance of prenatal environmental factors and gut-brain axis in neurodevelopment. May inform development of microbiome-targeted interventions, though human studies needed to validate translational relevance.

Animal study findings may not directly translate to humans. Sample size not reported, limiting statistical power assessment. Single environmental exposure model may not reflect complex human autism etiology. Long-term effects and reversibility of changes not examined.

Autism spectrum disorder (ASD) involves complex genetic-environmental interactions. Prenatal valproic acid (VPA) exposure, a known environmental risk factor, induces ASD-like phenotypes in rodents, although the mechanisms linking gut microbiota dysbiosis to neurobehavioral deficits remain unclear. Evidence suggests gut-brain axis dysregulation via altered microbial diversity and reduced short-chain fatty acid (SCFA)-producing taxa contributes to ASD pathogenesis. This study investigated whether prenatal VPA exposure drives ASD-like behaviors through gut dysbiosis and SCFA-producer depletion (e.g., Clostridia, Lachnospiraceae), exploring neuroinflammation and oxidative stress as mechanisms.

An ASD rat model was established by maternal VPA injection during specific gestational days. Behavioral tests assessed anxiety, sociability, repetitive behaviors, and cognition. Gut microbiota composition (16S rRNA sequencing), cytokine levels (ELISA), oxidative stress markers (biochemical assays), and microglial activation (Iba1 immunofluorescence) were analyzed. VPA-exposed offspring showed ASD-like behaviors accompanied by neurodevelopmental toxicity, manifesting as social deficits, repetitive grooming, and impaired memory.

Concurrently, gut analysis revealed reduced alpha diversity and depleted SCFA-producers (e.g., Clostridia, Lachnospiraceae), alongside increased Bacteroidia and Enterobacteriaceae. Neuroinflammation (elevated IL-1β, IL-6, TNF-α, microglial activation) and oxidative stress (reduced GSH, SOD; elevated MDA, NO) were evident. Multivariate analyses linked dysbiosis to behavioral impairments. Prenatal VPA exposure induces gut microbiota dysbiosis, potentially exacerbating neuroinflammation and oxidative stress to drive ASD-like phenotypes.

This establishes a mechanistic link between prenatal insults, gut-brain axis disruption, and neurodevelopmental abnormalities, highlighting microbial modulation and SCFA supplementation as potential ASD therapeutics. Furthermore, integrating behavioral, microbial, and molecular analyses advances understanding of gut-brain interactions in ASD and identifies microbiota-metabolite pathways as targets for neurodevelopmental disorders.