Exposure to alpha-glycosyl isoquercitrin from gestation to adulthood increases synaptic densities of glutamatergic and GABAergic inputs in the hippocampal dentate gyrus in rats

Exposure to alpha-glycosyl isoquercitrin (AGIQ) from gestation to adulthood has been shown to enhance synaptic plasticity in the hippocampal dentate gyrus (DG) and facilitate fear memory extinction in rats. Here, we investigated the effect of exposure to 0.5 % AGIQ in the diet from gestational day 6 to postnatal day 77 in rats on excitatory and inhibitory inputs in the DG. AGIQ increased VGLUT2 immunoreactivity in the granule cell layer and PSD95 immunoreactivity in the whole structure. AGIQ also increased VGAT immunoreactivity in all DG laminae as well as the number of hilar GABAergic interneurons expressing NMDAR2D in subpopulations expressing CB1R, parvalbumin or somatostatin. The GABAergic input was dominant to the glutamatergic input. These results suggest that AGIQ increases synaptic densities of both excitatory and inhibitory inputs in the DG. AGIQ may upregulate NMDAR2D in diverse interneuron subpopulations, thereby enhancing structural plasticity in granule cells, which might facilitate fear memory extinction.