The evaluation of vascular response in type 1 diabetic rats treated with 1,25-dihydroxycholecalciferol

The aim of this study was to evaluate the effects of 1,25-dihydroxycholecalciferol on blood glucose levels and vascular response, which have an important role in maintaining cardiovascular health and in preventing and improving various complications related to diabetes. For this purpose, 28 male Sprague Dawley rats, were divided into four groups; control (K), vitamin D (VitD), diabetes (D) and Diabetes+Vitamin D (DVD). Group D and DVD were injected single dose of 50 mg/kg streptozotocin to induce diabetes, while K and D groups was administered an equal volume of citrate buffer solution intraperitoneally. After the diagnosis of diabetes, VitD and DVD groups were administered 1,25-dihydroxycholecalciferol 120 ng/100 g/once a week, subcutaneously for 6 weeks. Blood glucose levels, body weight and blood pressure measurements were recorded weekly. At the end of experiment, contraction and relaxation responses of thoracic aorta rings were evaluated in in-vitro organ bath. Diabetes decreased the body weights from week 1 (P<0.001). The mean blood glucose levels decreased in DVD group compared with D group at 5 and 6 weeks (P<0.05 and P=0.069, respectively). Diabetes decreased mean blood pressure values from the 2nd week (P<0.01). While the KCl contraction response was higher in the VitD group than the other groups (P<0.01), the phenylephrine contraction response was lower in the VitD and DVD groups (P=0.076). In addition, the acetylcholine relaxation responses of the diabetic groups were higher than the non-diabetic groups (P=0.082). Experimental results showed that 1,25-dihydroxycholecalciferol in type 1 diabetic rats could lower blood glucose levels, but had no significant effect on blood pressure and aortic contraction and relaxation responses. Keywords: 1,25 dihydroxycholecalciferol, acetylcholine, aorta, blood pressure, type 1 diabetes.