Maternal effects on offspring metabolism and behaviour – impact of diet and stress

Margaret J. Morris, Pharmacology, Medical Sciences, UNSW Sydney, NSW 2052, Australia.

Maternal obesity during pregnancy is directly associated with fetal growth and confers increased risk of obesity in adulthood. After demonstrating beneficial effects of exercise after weaning in offspring, we investigated whether maternal exercise prior to and during pregnancy has positive effects on offspring.

Female Sprague Dawley rats were fed standard chow or high fat diet (HFD), yielding lean and obese dams. After 6 weeks of diet, half were exercised (running wheels) while half remained sedentary until the end of pregnancy. Mating began after 10 days of exercise and pre-pregnancy diet was maintained. Blood, feces and tissues were collected from both sexes at postnatal day (PND) 19. In lean dams, maternal exercise significantly reduced pup birth weight (P<0.05). At PND19, body weights were significantly higher in pups from obese dams (P<0.01) regardless of pup sex and maternal activity. Significant decreases in gut bacterial diversity were observed in obese versus lean dams, with little impact of maternal exercise. Maternal obesity significantly impacted offspring microbiome composition. Maternal exercise altered the abundance of 88 microbial taxa in offspring of lean dams, with modest effects in offspring of obese dams. Behaviour was tested in brothers of these rats at 6 weeks of age, and increased anxiety-like behaviour was observed in offspring of lean dams who exercised. Interestingly maternal obesity appeared to attenuate the anxiety-like behaviour induced by maternal exercise.

Thus changes in the maternal gut microbiota induced by HFD were transferred to their offspring and maternal exercise during pregnancy resulted in gut microbiota dysbiosis in offspring of lean dams. Overall modest levels of maternal exercise during pregnancy decreased metabolic risk conferred by maternal obesity. The impact of exercise during pregnancy on the gut microbiome and behaviour warrants further investigation. Current work is examining the association between the gut microbiome and changes in inflammatory and neurogenic mediators in the brain.