Effects of high-monounsaturated fat diet in combination with exercise training on ketone metabolism and glycemic control in diabetic rats

Abstract

The present study aimed to investigate the effects of high-monounsaturated fatty acid (MUFA) plus exercise on ketone metabolism and glycemic control in rats with diabetes mellitus (DM). Diabetes was induced in male Wistar rats (n=38) by intraperitoneal injection with streptozotocin (55 mg/kg BW). The diabetic rats were divided into five groups: 1) Control: DM + regular diet (n=7) 2) DM + high-saturated fatty acid (SFA) diet (n=8) 3) DM + high-MUFA diet (n=8) 4) DM + exercise (Ex) + regular diet (n=7) 5) DM + high-MUFA + Ex (n=8). Exercise training program was carried out progressively on a treadmill twice daily, 5 days/wk for twelve weeks. At the end of experiment, cardiac blood was rapidly taken for measuring plasma glucose, HbA1C, insulin, serum free fatty acid (FFA) and serum β-hydroxybutyrate. The liver and gastrocnemius muscle were collected to determine enzymatic activity of β-hydroxybutyrate dehydrogenase used in hepatic ketone body synthesis pathway and 3-ketoacyl-CoA transferase used in muscle ketone body utilization pathway, respectively. The results revealed that when compared with Control, DM+MUFA group showed a significant decrease (p<0.05) in plasma glucose but not HbA1C, FFA and β-hydroxybutyrate levels. In DM+Ex group, plasma glucose and HbA1C were unchanged while FFA was significantly decreased (p<0.05) and β-hydroxybutyrate tended to decrease. In DM+MUFA+Ex group there was a significant decrease (p<0.05) in plasma glucose, HbA1C, serum FFA and serum β-hydroxybutyrate levels. The activity of β-hydroxybutyrate dehydrogenase was significantly decreased (p<0.05) and that of 3-ketoacyl-CoA transferase was significantly increased only in DM+Ex and DM+MUFA+Ex groups. In conclusion, MUFA alone did not affect ketone metabolism. A combination of MUFA and exercise was more effective than either MUFA or exercise alone for improvement of glycemic control and ketone metabolism. The decrease in ketone bodies level was mediated by decreasing the activity of hepatic ketone synthesis and increasing the activity of muscle ketone utilization pathway.