Diet-induced obesity in young mice: Consequences on the pancreatic intrinsic nervous system control of insulin secretion.

INTRODUCTION

Obesity has become a pandaemic even in children. We aimed to investigate the impact of obesity in youth on later pancreatic intrinsic nervous system (PINS) phenotype and control of insulin secretion.

METHODS

Young mice (5-week-old, T0 group) were fed either a normal diet (ND group) or a Western diet (WD group) for 12 weeks. Pancreas nervous system density, PINS phenotype and pancreas anatomy were analysed by immunohistochemistry at T0 and in adulthood (ND and WD groups). Insulin secretion was also studied in these 3 groups using a new model of ex vivo pancreatic culture, where PINS was stimulated by nicotinic and nitrergic agonists with and without antagonists. Insulin was assayed in supernatants by ELISA.

RESULTS

Pancreas nervous system density decreased with age in ND ( < .01) but not in WD mice ( = .08). Western diet decreased the PINS nitrergic component as compared to normal diet ( < .01) but it did not modify its cholinergic component ( = .50). Nicotinic PINS stimulation induced greater insulin secretion in ND compared to WD mice ( < .001) whereas nitrergic stimulation significantly decreased insulin secretion in ND mice ( < .001) and tended to increase insulin secretion in WD mice ( = .08). Endocrine pancreas anatomy was not modified by the Western diet as compared to the normal diet ( = .93).

CONCLUSIONS

Early Western diet induced neuronal density and phenotype changes in PINS that might be involved in the pancreas insulin secretion dysfunctions associated with obesity.