541 VITAMIN D ATTENUATES OXIDATIVE STRESS IN A RAT MODEL OF DIABETES-INDUCED AORTIC STIFFNESS

Abstract

Background: Emerging evidence suggests that increased oxidative stress is implicated in the diabetic macrovascular complications. This study aimed to examine the effects of diabetes on the elastic properties of the aorta and the protective effects of vitamin D supplementation. Methods: Diabetes was induced by streptozotocin, followed by oral administration of cholecalciferol (500 IU/kg) for 10 weeks. Aortic pulse wave velocity (PWV) was recorded over a mean arterial pressure (MAP) range of 50 to 200 mmHg using a dual pressure sensor catheter. Oxidative stress index (OSI) was assessed by measuring total antioxidant capacity (TAC) and the level of total peroxides in the liver and serum. Advanced glycation end-products (AGEs) were determined in aortic samples by an immunochemical assay. Results: In diabetic rats, PWV was significantly elevated across MAP range between 170 and 200 mmHg, compared to control rats (7.0 ± 0.5 m/s vs 5.7 ± 0.7 m/s at MAP 170 mmHg, respectively, P< 0.05). PWV across lower MAP range did not reveal any significant differences between all groups. Diabetes was associated with significantly increased OSI in the liver and AGEs in the aorta, and reduced TAC in the serum. Cholecalciferol did not improve aortic stiffness, despite high levels of 25(OH)D in the treatment group. Changes in biomarkers of oxidative stress were significantly improved by cholecalciferol. Conclusion: PWV profile determined under isobaric conditions demonstrated differential effects of uncontrolled diabetes on aortic stiffness. Diabetes was also accompanied by increased oxidative stress. Vitamin D did not improve aortic stiffness, but attenuated oxidative stress in diabetic rats.