Dysregulation of Glu/GABA and reduction of triglycerides contribute to valproic acid-induced autism model in zebrafish.

Abstract

Autism spectrum disorders are neurodevelopmental conditions that pose substantial diagnostic and therapeutic challenges. Maternal exposure to valproic acid (VPA) during pregnancy is a well-established risk factor associated with autism-like behaviors in offspring. This study characterized the metabolic phenotypes in the brain tissue of larval zebrafish following VPA exposure. Zebrafish were exposed to 4 μM VPA from 2 hours post-fertilization (hpf) until 4.5 days post-fertilization (dpf), and locomotor activity was assessed at 14 dpf. Comprehensive metabolomic profiling via ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) identified 2,613 metabolites in brain tissue, of which 50 showed potential links to autism (CTRL_CV < 15%, VPA_CV < 20%). Significant reductions were observed in the levels of glutamine, glutamate, and triacylglycerol (TG). Nile red staining confirmed profoundly decreased TG deposition in the dorsal telencephalon (pallium), habenula, and cerebellum of VPA-exposed zebrafish. Furthermore, in vivo imaging revealed attenuated fluorescence intensity in excitatory glutamatergic and inhibitory GABAergic neurons within the habenular nucleus and optic tectum, corresponding to reduced TG levels. Conversely, the cerebellar corpus (central cerebellar body) and inferior olive nucleus exhibited an increase in excitatory glutamatergic neurons and a reduction in inhibitory GABAergic neurons, indicating an excitatory/inhibitory (E/I) imbalance. Collectively, these findings suggest that VPA may promote autism pathogenesis by disrupting the glutamine-glutamate cycle and impairing triacylglycerol metabolism in the zebrafish brain. These findings offer novel insights into metabolic dysfunction in ASD and may facilitate the identification of potential diagnostic biomarkers.