Comparative effects of zinc, selenium and vitamin E or their combination on carbohydrate metabolizing enzymes and oxidative stress in streptozotocin induced-diabetic rats

Abstract

Objective: It is well documented that oxidative stress is a basic mechanism behind the development of diabetic state. The current study was undertaken to elucidate the hypoglycemic role of zinc, selenium and vitamin E and their mixture in comparison with the antidiabetic drug glibenclamide.

Materials and methods: Male Wistar rats weighing 250 +/- 50 g were made diabetic by injection with a single i.p. dose of streptozotocin (STZ) (65 mg/kg b. wt). Diabetic groups were simultaneously i.p. injected either with zinc chloride (ZnCI2) (5 mg/kg) or with selenium and vitamin E (1.5 mg/kg as sodium selenite and vitamin E 1000 mg/kg) or with zinc, selenium and vitamin E each element i.p. injected according to its corresponding therapeutic dose daily for one month. Another group was orally treated daily with glibenclamide drug (5 mg/kg) for one month.

Results: Blood and tissue samples were collected at day 3 post STZ injection (from one group serum glucose level significantly elevated < or = 300, p < or = 0.05) and at day 30 post-treatment in other groups. Liver function, nitric oxide (NO), malondialdehyde (MDA) and phosphoenol pyruvate carboxykinase (PEPCK) were significantly increased, while superoxide dismutase (SOD), reduced glutathione (GSH), total protein, lactate dehydrogenase (LDH), pyruvate kinase (PK) and hexokinase (HK) were inhibited after STZ treatment. Histological examination of diabetic liver showed necrosis and degenerative changes of hepatocytes. Treatment of diabetic rats with ZnCI2, selenium and vitamin E or their combination blunted the increment in serum glucose induced by STZ, preserved liver architecture and ameliorated all the previous mentioned biochemical parameters.

Conclusions: It was found that, the combined administration of zinc, selenium and vitamin E exhibited a more remarkable effect than either zinc or selenium and vitamin E. So, the results clearly indicate the beneficial effects of micronutrients combination in controlling hyperglycemia.