Nigella sativa seed decreases endothelial dysfunction in streptozotocin-induced diabetic rat aorta

Objective: Diabetes is an important risk factor for cardiovascular events. The great percent of morbidity in patients with diabetes is due to endothelial dysfunction. The present study investigated the effects of hydroalcholic extract of Nigella sativa (N. sativa)  on contractile and dilatation response of isolated aorta in streptozotocin (STZ)-induced diabetic rat. Materials and Methods: Rats were divided into six experimental groups (control, untreated STZ-diabetic, and N. sativa hydroalcholic extract or metformin-treated diabetic rats). Treated rats received N. sativa extract (100, 200, and 400 mg/kg) or metformin (300 mg/kg) by gavage, daily for 6 weeks. Isolated rat thoracic rings were mounted in an organ bath system then contractile and dilatation responses induced by phenylephrine (PE), acetylcholine (ACh), potassium chloride (KCl), and sodium nitroprusside (SNP) were evaluated in different situations. Results: The lower concentrations of N. sativa seed extract (DE 100 and DE 200) and metformin significantly reduced the contractile responses to higher concentrations of PE (10-6 - 10-5 M) compared to diabetic group (pThe relaxation response to Ach 10-8M, was increased in DE 200 and metformin groups compared to diabetic group (p