Selenium restores defective beta-adrenergic receptor response of thoracic aorta in diabetic rats

Increased oxidative stress is one of the basic contributors to the development of the cardiovascular complications in diabetes. Both endothelial and vascular smooth muscle cell dysfunctions are the main sign involved in the pathogenesis of diabetic cardiovascular dysfunction. Matrix metalloproteinases (MMPs) are expressed in the vasculature, and participate in tissue remodeling under pathological conditions such as increased oxidative stress, whereas little is known about effect of hyperglycemia on regulation of MMPs in vascular system. Therefore, we aimed to evaluate the effect of an antioxidant, sodium selenate treatment (0.3 mg/kg for 4 weeks) on function of streptozotocin-diabetic rat aorta. Sodium selenate treatment improved significantly impaired isoproterenol-induced relaxation responses and contraction responses of the aortic strips, and exhibited marked protection against diabetes-induced degenerative changes in the smooth muscle cell morphology. Biochemical data showed that sodium selenate treatment induced a significant regulation of MMP-2 activity and protein loss as well as normalization of increased levels of tissue nitrite and protein thiol oxidation. In addition, this treatment restored diabetes-induced increased levels of endothelin-1, PKC, and cAMP production in the aortic tissue. Taken together, our data demonstrate that these beneficial effects of sodium selenate treatment in diabetics are related to be not only inhibition of increased oxidative stress but also prevention of both receptor- and smooth muscle-mediated dysfunction of vasculature, in part, via regulation of MMP-2. Such an observation provides evidence for potential therapeutic usage of selenium compounds for the amelioration of vascular disorders in diabetes.