Vitamin D downregulates key genes of diabetes complications in cardiomyocyte.

Abstract

Vitamin D deficiency has been reported to be associated with the incidence of type 1 and type 2 diabetes and worsening of diabetes complications. This study was designed to investigate the effect of vitamin D treatment on the expression of five key genes involved in the development of diabetic cardiomyopathy. Twenty-four male Sprague-Dawley rats were randomly divided into three groups. The first group served as control and the other two groups received an intraperitoneal injection of 45 mg/kg streptozotocin (STZ) to develop diabetes. Then groups were treated for 4 weeks either with placebo or vitamin D (two injections of 20,000 IU/kg). Serum levels of glucose, insulin, HbA1c, and advanced glycation end products (AGEs), as well as the gene expression of AGE cellular receptor (RAGE), glyoxalase, aldose reductase, O-GlcNAc transferase (OGT), and glutamine-fructose-6-phosphate aminotransferase (GFAT) and nuclear factor-kB (NF-kB) activity of nuclear extracts were assessed at the end of experiment. Increment in serum cholecalciferol could improve hyperglycaemia and hypoinsulinemia in diabetic rats. In addition, a significant reduction was observed in RAGE, OGT, and GFAT gene expression and NF-kB activity in cardiac myocytes. Vitamin D might contribute in reducing diabetic cardiomyopathy not only by improving blood glucose and insulin levels but also via downregulating AGE and hexosamine pathways and decreasing NF-kB activity in heart tissue.