Maternal exercise and high-fat diet affect hypothalamic neural projections in rat offspring in a sex-specific manner

This study aimed to investigate the effect of maternal high-fat (HF) diet and exercise during gestation and lactation on hypothalamic neural projection development in the offspring. Pregnant Sprague-Dawley rats were fed a CHOW or HF diet during gestation and lactation, and further divided into two subgroups: voluntary exercised and sedentary. Offspring's brains and tissue were collected at weaning and 16 weeks of age. Maternal exercise downregulated dams' body weight and food intake during lactation, but failed to normalize increased fat weight, plasma and milk leptin levels of HF dams at weaning. Maternal HF diet significantly increased offspring's body weight, adipose depots, plasma insulin, and leptin at weaning and had long-term effect on body weight of male offspring, while maternal exercise decreased offspring's body weight from 3 to 5 weeks of age in both sexes. At weaning, maternal exercise decreased αMSH fiber density and maternal HF diet impaired agouti-related peptide fiber density in the paraventricular nucleus of hypothalamus of male pups, while maternal HF diet disrupted αMSH fiber density in the paraventricular nucleus of hypothalamus of female pups. The impaired αMSH fiber density was consistent with reduced STAT3 signaling in the arcuate nucleus of hypothalamus, while the reduced agouti-related peptide fiber density was consistent with reduced ERK1/2 signaling in the arcuate nucleus of hypothalamus. The impaired hypothalamic projections were compensated in adulthood in both sexes. Our findings suggest that maternal HF diet and exercise exerts different effects on hypothalamic neural projections development through distinct signaling pathways in a sex-specific manner.