|ISSN No. 1606-7754 Vol.15 No.2 August 2007|
The beneficial effect of vitamin E supplementation on zinc status, carbohydrate metabolism, transaminases and alkaline phosphatase activities in alloxan-diabetic rats fed on zinc deficiency diet
Zine Kechrid, EL-Hadjla Derai and Naima Layachi
Laboratory of Biochemistry and Microbiology, Department of Biochemistry, Faculty of Sciences, University of Annaba, Annaba, Algeria
The aim of this study was to investigate the beneficial effect of vitamin E supplementation on zinc deficiency in experimental diabetes. Male alloxan-diabetic Wistar, albino rats of 10 weeks of age were divided into three groups. The first group received a diet containing 54 mg zinc/kg (adequate zinc group, AZ), the second group received a diet containing 1mg zinc/kg (zinc deficient group, ZD), and the third group received a diet containing 1mg zinc/kg supplemented with vitamin E (500mg/kg diet) (ZD+VE). Body weight gain and food intake of all rats were recorded regularly over a period of four weeks. On day 28, after overnight fasting, animals were killed and blood glucose, serum cholesterol, serum triglycerides, serum protein, serum urea, serum zinc, femur zinc, pancreatic zinc, testis zinc, liver glutathione concentrations and serum glutamic oxalic transaminase (GOT), serum glutamic pyruvic transaminase (GPT) and serum alkaline phosphatase activities were determined on blood and tissue samples. Body weight gain of zinc deficient diabetic animals at the end of four weeks of dietary manipulation was significantly lower than that of zinc adequate diabetic animals. Dietary zinc intake significantly increased blood glucose, serum cholesterol, serum triglycerides, and serum urea of zinc deficient diabetic rats. In contrast, serum zinc, femur zinc, pancreatic zinc, serum protein and liver glutathione levels were lower. The consumption of zinc deficient diet led also to an increase in serum GOT, GPT coupled with a decrease in serum alkaline phosphatase. Vitamin E ameliorated all the previous parameters. In conclusion, the present study demonstrates that vitamin E supplementation significantly reduced the severity of zinc deficiency in diabetes mellitus. (Int J Diabetes Metab 15: 46-50, 2007)
Keywords: Diabetic rats, alloxan, zinc deficiency, vitamin E, transaminases
Many of the features of zinc deficiency and essential fatty acid (EFA) deficiency are similar in humans and animals. These similarities include dermal lesion, poor growth, and bone and joint disorders. Several ways in which EFA and zinc may interact have been proposed. O’Dell1 suggested that one point of interaction may be related to EFA oxidation, with zinc deficiency producing a high oxidation rate of unsaturated fatty acids in cell membranes leading to decreased membrane stability. Zinc plays a key role in the regulation of insulin production in pancreatic tissue. It seems reasonable therefore, that any changes in body zinc status could affect production, storage and secretion of insulin. There are several reasons for suspecting that an abnormal zinc metabolism could play a role in the pathogenesis of diabetes mellitus, which is accompanied by severe oxidative stress (especially lipid peroxidation) as a result of an increased oxygen free radical production.2 Oxidative stress, induced by hyperglycemia, leads toan accelerated development of cellular and vascular damage. Bettger and co-workers3 have reported that supplementation of zinc-deficient chicks with vitamin E significantly reduced the severity of skin and joint pathology. Dietary supplementation with the antioxidant vitamin E has been suggested as a possible means of controlling diabetic complications.4,5 The administration of antioxidant, such as vitamin E may be needed to prevent damage to lipids by oxygen free radicals and thus signs of zinc deficiency in diabetic patients.6 Therefore, the aim of this study was to examine the effects of dietary vitamin E supplementation and its beneficial effect on diabetic pathology observed in zinc deficient rats by evaluating body weight gain, food intake, zinc status, carbohydrate metabolism and some enzymes activities in alloxan diabetic rats.