Possible role of trace elements in the hypoglycemic effect of plants extract in diabetic rats

The present study is designed to investigate the possible role of zinc, copper, manganese, and selenium on the hypoglycemic action of a plants mixture and alfalfa using a diabetic rat model. Diabetes was induced in male Wister rats using streptozotocin and confirmed by estimation of glucose levels in blood and urine and further by histologic examination of the pancreas. The animals were treated with the plants mixture and alfalfa extracts orally by gastric intubation for 7 days. Untreated normal and diabetic rats were included as controls. After evaluating glucose tolerance, animals were sacrificed and organs harvested for trace element analysis and histopathological study. The concentration of zinc, copper, manganese, and selenium in plasma, liver, and pancreas of diabetic rats was significantly lower than those of nondiabetic controls. Treatment of diabetic rats with plants mixture and alfalfa significantly decreased the blood glucose concentration but increased the levels of zinc, copper, manganese, and selenium in plasma, liver, and pancreas. Similar changes occurred in the nondiabetic normal control animals treated with the same products. Histological and immunohistochemical examination also confirmed the presence of more β-cells in the islets of treated diabetic animals compared with untreated diabetic controls. There was no histological evidence of damage to the liver of either diabetic or normal control animals treated with the plants extract. The present study indicated that treatment of diabetes with naturally available plants mixture appears to be effective and the hypoglycemic effect could be through a multimechanism action including that exerted by the trace element content in the different tissues including the pancreas. J. Trace Elem. Exp. Med. 17:31–44, 2004. © 2004 Wiley-Liss, Inc.