Prenatal maternal HFD exposure impairs cognition via a hippocampal NMDA mechanism

Maternal obesity increases the risk of neurodevelopmental disorders and cognitive impairments in offspring later in life. Most animal studies investigated the effects of maternal high-fat diet (HFD) from pre-mating to lactation on offspring neurodevelopment and cognitive function. However, the specific impact of in-utero exposure to maternal HFD on the cognitive function in offspring remains limited. In this study, female dams were fed laboratory chow or HFD for 11 weeks: 8 weeks before conception and during gestation. To isolate the prenatal effects, newborns were reared by foster mothers under control-diet conditions during lactation. Behavioral tests were conducted between postnatal days 42 and 56. Our results demonstrate that maternal HFD exposure in utero impaired spatial working memory and spatial memory, and also caused depression-like behavior in offspring. These behavioral abnormalities were associated with reduced hippocampal NMDA receptor expression, diminished neurogenesis, and deficits in hippocampal long-term potentiation (LTP). In addition, intrahippocampal microinjection of NMDA receptor antagonists that block NMDA ion channels or compete for glutamate binding effectively reduces hippocampal long-term potentiation (LTP), resulting in deficits in spatial learning and memory. Furthermore, microinjection of NMDA into the hippocampus bilaterally activated NMDA receptor signaling, leading to the amelioration of behavioral abnormalities in HFD offspring. In summary, alteration of hippocampal NMDA receptors induced by prenatal maternal HFD exposure is associated with spatial learning and memory deficits in offspring.