These findings suggest that impaired adult neurogenesis in the ventral hippocampus is a common hallmark across ASD mouse models and may underlie social behavior deficits. This study provides insight into region-specific neurogenic alterations linked to ASD pathophysiology and highlights potential targets for therapeutic interventions.

In this study, we investigated social behavior and adult hippocampal neurogenesis in C57BL/6J mice prenatally exposed to VPA or nicotine, as well as in genetically modified ASD models, including IQSEC2 knockout (KO) and NLGN3-R451C knock-in (KI) mice. Sociability and social novelty preference were evaluated using a three-chamber social interaction test. Adult hippocampal neurogenesis was assessed by BrdU and DCX immunofluorescence to identify newborn and immature neurons.

VPA-exposed mice displayed significant deficits in social interaction, while nicotine-exposed mice exhibited mild impairment in social novelty preference. Both IQSEC2 KO and NLGN3-R451C KI mice demonstrated reduced adult neurogenesis, particularly in the ventral hippocampus, a region associated with social behavior and emotion. Across all ASD mouse models, a significant reduction in BrdU+/NeuN+ cells in the ventral hippocampus was observed, while dorsal hippocampal neurogenesis remained relatively unaffected. Similar reductions in DCX-positive cells were identified in VPA, nicotine, and NLGN3-R451C KI mice, indicating impaired proliferation or differentiation of neuronal progenitors.