Effect of 1, 25(OH)2 vitamin D3 on glucose homeostasis and DNA damage in type 2 diabetic mice

Aims: The purpose of the study was to examine the effect of 1, 25(OH)2 VitaminD(3) supplementation on type 2 diabetic (T2DM) mice. Materials and Methods: A total of 24 mice were taken and divided into three groups of control; diabetic and diabetic + vitamin D supplemented ones. Serum calcium level, fasting blood glucose level (FBG), hexokinase activity, glucose-6-phosphatse and fructose 1,6 bisphosphatase activity were measured to establish a relevant correlation between vitamin D supplementation and hyperglycemia in T2DM. Results: There occurred an increase in FBG levels (250 +/- 0.41 mg/dl) and a significant decrease in serum calcium levels in the diabetic group (8.63 +/- 0.40 mg/ml) both of which reached near control levels on vitamin D-3 supplementation. The activity of the glucose metabolic enzymes was also assayed in diabetic group and was found to be deviated from control group; hexokinase (0.0241 +/- 0.014 mu g/mg/ml) FBPase (0.433 +/- 0.002 mu g/mg/ml) and G6Pase (0.918 +/- 0.02 mu g/mg/ml). However, the activity of these enzymes returned to near control values with hexokinase activity reaching 0.717 +/- 0.003 mu g/mg/ml on vitamin D-3 supplementation. The FBPase and G6Pase activities were decreased to 0.2733 +/- 0.008 mu g/mg/ml and G6Pase 0.71 +/- 0.01 mu g/mg/ml respectively. In addition to enzymatic analysis, the organs of all three groups of mice were subjected to comet assay. The diabetic group receiving vitamin D supplementation showed a marked recovery exhibiting shorter tail length both in liver (21.80 +/- 2.40 mu m) and pancreatic cells (19.25 +/- 1.90 mu m) as compared to the diabetic group exhibiting a tail length of 30.41 +/- 2.50 mu m and 32.45 +/- 2.87 mu m in liver and pancreatic cells respectively. Conclusion: The present study shows that vitamin D-3 supplementation is positively correlated with decrease in blood glucose level and serum calcium level in fasting condition. This suggests a positive influence of vitamin Don glucose homeostasis. Besides, the activity of various glucose metabolic enzymes (hexokinase, FBPase and G6Pase) as shown by our results and the remarkable shortening of DNA tail length in vitamin D supplemented diabetic group as compared to diabetic group without supplementation further support the idea that vitamin D supplementation might be an add-on therapy for patients with T2DM. (C) 2012 Elsevier Inc. All rights reserved.