Exposure to maternal obesity per se programs sex-differences in pancreatic islets of the offspring

Summary Maternal obesity increases type 2 diabetes (T2D) risk in the offspring. Given that nearly half of women of child-bearing age in many populations are currently overweight/obese, it is key that we improve our understanding of the impact of the in utero /early life environment on offspring islet function. Using a well-established mouse model of diet-induced obesity, we examined offspring islets before the onset of metabolic dysfunction. This allowed us to determine inherent changes, in males and females, which are distinct from the response of islets to an existing obesogenic, insulin resistant milieu hence identifying islet dysregulation reflecting very early manifestation of the disease before the onset of disrupted glucose homeostasis. Female offspring of obese dams displayed higher glucose-stimulated insulin secretion and mitochondrial respiration, increased expression of estrogen receptor α and decreased cleaved-caspase 3 and Bax:Bcl-2 reflecting reduced susceptibility to apoptosis. In contrast, male offspring of obese dams displayed compromised mitochondrial respiration characterised by decreased ATP synthesis-driven respiration and increased “uncoupled” respiration and reduced docked insulin granules in β-cells. Thus, maternal obesity “programs” sex-differences in offspring islet function. Islets of female but not male offspring appear primed to cope with a nutritionally-rich postnatal environment, which may reflect differences in future T2D risk.