Combined Maternal and Offspring Vitamin D3 Supplementation Ameliorates Autism-Like Behaviors via VDR Pathway Activation, Neuroinflammatory Suppression, and Metabolic Homeostasis Restoration.

BACKGROUND

Autism Spectrum Disorder (ASD) is a widespread neurodevelopmental disorder with no approved medications targeting its core symptoms. Based on the "dual-hit" hypothesis combining Maternal Immune Activation (MIA) and Maternal Separation (MS), this study investigated whether combined maternal and offspring vitamin D3 supplementation could ameliorate autism-like behaviors by modulating the VDR pathway, neuroinflammation, and metabolic homeostasis.

MATERIALS AND

METHODS

A "dual-hit" ASD mouse model was established in C57BL/6 offspring by combining maternal immune activation (MIA) with maternal separation (MS). Pregnant mice were randomly allocated into three groups (n = 5 per group): Control, Model (MIA+MS), and Intervention (MIA+MS + high vitamin D diet). Offspring in the intervention group continued to receive vitamin D supplementation post-weaning (from 3 weeks of age) until 8 weeks. Offspring behavioral tests were conducted on postnatal days 42-56, with the litter serving as the unit of analysis. Serum, brain tissue, colon contents, and liver samples were subsequently collected and analyzed using ELISA, Western blot, LC-MS, and immunohistochemistry.

RESULTS

Compared with controls, MIA+MS offspring exhibited significant social deficits, anxiety, and repetitive behaviors. Combined vitamin D supplementation markedly improved social preference (P<0.0001), reduced anxiety (P<0.001), and decreased repetitive behaviors (P < 0.05). It also upregulated VDR expression in the brain (P<0.01), reduced neurotoxic metabolites (indoxyl sulfate, 6-phosphogluconic acid, and kynurenine pathway intermediates), lowered pro-inflammatory cytokines (IL-1β (P<0.001), IL-6 (P<0.001), TNF-α (P<0.001)), and restored carnitine metabolic homeostasis by modulating TMLHE expression and function.

CONCLUSION

Combined maternal and offspring vitamin D3 supplementation significantly improves autism-like behaviors in a "dual-hit" ASD model. The observed protective effects may involve activation of the VDR pathway, reduction of neuroinflammation and neurotoxic metabolites, and systemic restoration of immune and metabolic homeostasis. These findings suggest the potential utility of vitamin D in ASD prevention and intervention, warranting further investigation.