Intranasal insulin ameliorates prenatal LPS-induced learning and memory impairments in adolescent male rats: A behavioral, electrophysiological, and molecular study

Prenatal stress, including maternal immune activation (MIA), affects cognitive performance in the offspring. Since insulin could improve cognitive function in several aspects, we hypothesized that intranasal insulin would attenuate MIA-induced learning and memory deficits. In the present study, the pregnant Wistar rats received lipopolysaccharide (LPS, 250 µg/kg) intraperitoneally on gestational day 15. Intranasal insulin (2 IU, 7 days) was administered to male pups from PND 34-47. During late adolescence, the Morris Water Maze and in vivo electrophysiological recording were performed in male rats to assess spatial learning and memory and long-term potentiation (LTP), respectively. Also, the hippocampal expression of BDNF and PSD-95 was evaluated using real-time PCR. Our results demonstrated that MIA impaired spatial learning and memory in the male pups. Hippocampal synaptic plasticity was also impaired in the adolescent male rats. However, intranasal administration of insulin could overcome MIA-induced impairments and improve learning, memory, and synaptic plasticity in the male pups. Although BDNF and PSD-95 levels were not altered in the hippocampus of MIA pups, intranasal insulin increased PSD-95 expression. Taken together, these findings suggest that intranasal insulin promotes cognitive performance in MIA-exposed pups during adolescence; however, the underlying molecular mechanisms remain to be elucidated.