Conclusions
Our work highlights, for the first time, positive modulation of hippocampus autophagy as potential mechanism underlying improvements in autistic behaviors, observed with metformin, as well as risperidone, therapy.
Methods
The effectiveness of metformin on alleviation of ASD-like behavioral deficits in adolescent rats exposed prenatally to valproic acid (VPA) was compared to that of risperidone. The potential modulatory effects of risperidone on hippocampal autophagic activity were also assessed and compared to those of metformin.
Results
Male offspring exposed to VPA during gestation exhibited marked anxiety, social impairment and aggravation of stereotyped grooming; such deficits were efficiently rescued by postnatal risperidone or metformin therapy. This autistic phenotype was associated with suppressed hippocampal autophagy; as evidenced by reduced gene/dendritic protein expression of LC3B (microtubule-associated proteins 1 light chain 3B) and increased somatic P62 (Sequestosome 1) protein aggregates. Interestingly, compared to risperidone, the effectiveness of metformin in controlling ASD symptoms and improving hippocampal neuronal survival was well correlated to its ability to markedly induce pyramidal neuronal LC3B expression while lowering P62 accumulation. Conclusions: Our work highlights, for the first time, positive modulation of hippocampus autophagy as potential mechanism underlying improvements in autistic behaviors, observed with metformin, as well as risperidone, therapy.