Neuro-regulator role of H2S in astrocyte activation and its effects on neurological damage and behavior of VPA-exposed rats

Autism spectrum disorder (ASD) is a complex neurodevelopmental disorder increasingly associated with aberrant astrocyte activation. Hydrogen sulfide (H 2 S) has recently emerged as a key regulator of astrocyte function, yet its role in ASD remains largely unexplored. Here, we investigated the association between H₂S modulation, ASD-like phenotypes, and astrocyte activation. In valproic acid (VPA)-exposed rats, H₂S were modulated using α-lipoic acid (LA) or aminooxyacetic acid (AOAA), a cystathionine β-synthase (CBS) inhibitor. Behavioral performance, neuronal injury, astrocyte phenotypes, H₂S levels, CBS expression and the homocysteine/cystathionine ratio were evaluated in vivo and in primary astrocytes. VPA-exposed rats exhibited reduced H₂S levels and CBS expression, an increased homocysteine/cystathionine ratio, ASD-like behavioral deficits and neuronal injury, and astrocyte activation toward a neurotoxic A1 phenotype. Elevation of H 2 S by LA was associated with improvements in ASD behavioral performance, reduced neuronal damage, reduced inflammatory cytokines and suppressed astrocyte activation, with changes in astrocyte marker expression towards a more A2-like, neuroprotective profile. Conversely, AOAA reversed these beneficial effects. Collectively, these findings suggested enhanced H₂S signaling is linked to improvements in ASD-like behavioral and neuropathological abnormalities, alongside modulation of astrocyte activation involving the CBS/H₂S pathway. These findings highlight the potential involvement of the CBS/H₂S axis in ASD-related pathology.