Streptozotocin-induced vascular and biochemical changes in rats: Effects of rosiglitazone vs. metformin

The aim was to investigate rosiglitazone and metformin effects on some vascular and biochemical changes associated with streptozotocin (55 mg/kg; i.p.)-induced hyperglycaemia in rats. Isolated aortas were used to evaluate their reactivity towards norepinephrine, acetylcholine, and sodium nitroprusside. Blood samples were used to assess the biochemical changes of some parameters viz., plasma lipid peroxides and nitric oxide levels and erythrocytic glutathione peroxidase activity. Hyperglycaemic animals orally received rosiglitazone (0.5 mg/kg) or metformin (150 mg/kg) daily for 2 weeks and their effects were determined 24 h after the last dose. Our results revealed that streptozotocin-induced hyperglycaemia is associated with impaired vascular reactivity towards various agents, increased lipid peroxides level, decreased glutathione peroxidise activity, and decreased nitric oxide level. Both drugs further decreased norepinephrine-induced contraction and improved acetylcholine- and sodium nitroprusside-induced relaxations. Rosiglitazone restored the alterations in all tested biochemical parameters while metformin restored only glutathione peroxidise activity. In conclusion both drugs show beneficial effects against the vascular dysfunction associated with hyperglycaemia which might be related to their euglycaemic activity in addition to anti-oxidant property of rosiglitazone and a direct effect of metformin on vascular smooth muscle.