Exercise Increases Insulin Content and Basal Secretion in Pancreatic Islets in Type 1 Diabetic Mice

Abstract

Exercise appears to improve glycemic control for people with type 1 diabetes (T1D). However, the mechanism responsible for this improvement is unknown. We hypothesized that exercise has a direct effect on the insulin-producing islets. Eight-week-old mice were divided into four groups: sedentary diabetic, exercised diabetic, sedentary control, and exercised control. The exercised groups participated in voluntary wheel running for 6 weeks. When compared to the control groups, the islet density, islet diameter, and β-cell proportion per islet were significantly lower in both sedentary and exercised diabetic groups and these alterations were not improved with exercise. The total insulin content and insulin secretion were significantly lower in sedentary diabetics compared to controls. Exercise significantly improved insulin content and insulin secretion in islets in basal conditions. Thus, some improvements in exercise-induced glycemic control in T1D mice may be due to enhancement of insulin content and secretion in islets.

Voluntary Exercise Protects Heart from Oxidative Stress in Diabetic Rats

“…Many beneficial effects of exercise such as increasing insulin sensitivity, improved glucose uptake and alleviating diabet complications in diabetic animals and patients are reported. [4][5][6][7][8] Exercise is a modifiable behavioral factor which can produce several beneficial effects, including improved cardiac functions and diabetes complications. 9 Exercise training has been reported to increase SOD 10,11 and also partially reverses oxidative stress in the brains of ethanol-exposed rats.…”

Physical exercise and pancreatic islets

“…Oliveira et al 10 observed that trained groups, independent of performing acute physical activity, presented greater insulin content in their pancreatic islets. Huang et al 11 also observed an increase in total insulin content in diabetic type I rats. This difference between our and other studies can be due to the pattern of exercise and/or exhaustion protocol adopted during training and acute exercise session, respectively.…”

“…Therefore, an improvement in insulin secretion capacity was observed in isolated pancreatic islets, stimulated with high glucose concentration, from rats submitted to swimming training for 8 weeks 10 and in the secretion stimulated by lower glucose concentration in type I diabetic rats. 11 It was also identified that 8 weeks of treadmill running activated growth pathways and cell survival in pancreatic islets, 12 increased anaplerotic enzyme activity 13 and the mediator agent responsible for higher insulin secretory capacity induced by exercise training would be interleucine 6 (IL-6).…”

Resistance jump training may reverse the weakened biomechanical behavior of tendons of diabetic Wistar rats

“…Therefore, training is of great importance to control diabetes by significantly raising the energy needs of the organism, thus requiring significant acute changes in cellular metabolism and neuroendocrine control 13 . Additionally, there is evidence that physical training is important to increase insulin content, promoting greater secretion of this hormone in isolated pancreatic islets in patients with diabetes mellitus, type 1 14 .…”