Abstract
Childhood obesity and early rapid growth increase the risk for type 2 diabetes. Such early overnutrition can be modeled in mice by reducing litter size. We investigated the effects of early overnutrition and increased dietary fat intake on β cell function in Swiss Webster mice. On a moderate-fat diet, early overnutrition accelerated weight gain and induced hyperinsulinemia in pups. Early overnutrition males exhibited higher β cell mass but reduced islet insulin content and Pdx1 expression. Males had a high diabetes incidence that was increased by early overnutrition, characterized by a progressive increase in insulin secretion as well as β cell death, indicated by histological analysis and increased circulating miR-375 levels. Females maintained normoglycemia throughout life. High-fat diet (HFD) increased diabetes incidence in males, whereas low-fat diet was completely protective. This protective effect was abolished in early overnutrition males transiently exposed to HFD in early life. Although Swiss Webster mice are not known to be diabetes-prone, the high diabetes incidence suggests an underlying genetic susceptibility that can be induced by overnutrition and increased dietary fat intake in early life. Thus, the nutritional environment in early life may impact long-term β cell function and increase diabetes risk, particularly in genetically susceptible individuals.
Highlights
A major risk factor for obesity and type 2 diabetes is prolonged overnutrition, with an obesogenic diet
Overnutrition pups exhibited higher pancreas, liver, kidney, and spleen weight as well as body length at P14 (Table 1), suggesting a more rapid growth rate. β cell mass was significantly increased in early overnutrition male pups at P14 (Fig. 1h,i) even when normalized to body weight
We have demonstrated that overnutrition and increased dietary fat in early life can promote the development of diabetes
Summary
A major risk factor for obesity and type 2 diabetes is prolonged overnutrition, with an obesogenic diet. It is difficult to investigate postnatal risk factors in humans without the confounding effects of in utero environment differences, both human and animal studies have noted increased diabetes risk with increased infant adiposity, early rapid growth, accelerated catch-up growth following intrauterine growth restriction (IUGR), and childhood obesity[2,11,12,13]. These observations suggest that the early developmental environment can have long-term effects on glucose homeostasis and contribute to disease. We hypothesized that overnutrition and increased dietary fat intake during the early postnatal period in Swiss Webster mice would adversely affect β cell development and long-term function
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