Effect of treatment with vitamin D plus calcium on oxidative stress in streptozotocin-induced diabetic rats

Abstract

Background: In diabetes mellitus, uncontrolled hyperglycemia has been reported to induce oxidative stress, which may lead to health complications. Vitamin D, however, acts as a non-enzymatic antioxidant to protect cells against oxidative stress and damage. Objective: To investigate the antioxidative effect of vitamin D combined with calcium in streptozotocin (STZ)-induced diabetic rats. Methods: Rats were divided into four groups (ten rats in each group). The first group (control) received a normal diet and water. The second group, including STZ-induced diabetic rats (diabetic controls), received a normal diet and water. The third group, also including STZ-induced diabetic rats, received vitamin D (2000 IU/day) with calcium (500 mg/kg/day) orally for 28 consecutive days. The fourth group consisted of STZ-induced diabetic rats that received insulin treatment for 28 consecutive days. Activities of superoxide dismutase (SOD), glutathione peroxidase (GPO) and catalase were measured in the liver tissues. The level of malonaldehyde (MDA) was measured in the plasma. Results: Diabetic rats showed a significant decrease in the activities of SOD, GPO and catalase compared to normal rats. Oral administration of vitamin D with calcium to diabetic rats caused a significant increase in the activities of SOD, GPO and catalase compared with the untreated group. Furthermore, the plasma level of MDA was significantly elevated in diabetic rats compared to normal rats. Diabetic rats treated with vitamin D and calcium had a significantly reduced level of MDA, suggesting that vitamin D with calcium played a vital role in the protection of tissues from damage by free radicals. Conclusion: Oral supplementation with vitamin D and calcium may be a useful treatment for diabetic patients to reduce/prevent the pathological complications of diabetes. Keywords: Antioxidant, Oxidative stress, Diabetes mellitus, STZ-induced diabetic rats, Malonaldehyde, Catalase, Superoxide dismutase, Glutathione peroxidase