Effects of high fat diet-induced obesity and pregnancy on prepartum and postpartum maternal mouse behavior

Obesity before and during pregnancy negatively affects the mental and physical health of the mother. A diet high in fat also increases the risk for anxiety, depression and cognitive dysfunction. We examined the effects of high fat diet (HFD)-induced obesity and pregnancy on maternal behavior, cognitive function and anxiety-and depression-like behaviors in mice. Four-week-old female CD-1 mice were placed on a HFD or regular chow diet (RCD) for 5 weeks. Mice were maintained on either diet as non-pregnant HFD and RCD groups, or allowed to breed, and then fed these diets throughout gestation, lactation and after weaning, as pregnant HFD and RCD groups. Mice on HFD but not on RCD for 5 weeks pre-pregnancy significantly gained weight and had impaired glucose clearance. Maternal behavior was assessed by nest building prepartum and pup-retrieval postpartum. Anxiety-like behavior was evaluated both prepartum and postpartum by elevated plus maze and cognitive function was assessed by the novel object recognition test postpartum. Anhedonia, a measure of impaired reward function, is an endophenotype of depression and was assessed by sucrose preference test pre-and post-weaning in dams. Mice on HFD in pregnancy exhibited both impaired maternal behavior and cognitive function in the postpartum period. We did not detect measurable differences between the HFD and RCD groups in anxiety-like behavior in the prepartum period. In contrast, HFD was also associated with anhedonia in pregnant mice pre weaning, and anxiety-like behavior post-weaning. Thus, HFD has a negative effect on maternal behavior in the outbred CD-1 mouse, which provides a model to study associated outcomes and related mechanisms.