Altered tissue content and cytosol distribution of trace metals in experimental diabetes

An insulin-dependent diabetic condition was induced in male Sprague-Dawley rats by streptozotocin injection. Ten days after administration of the diabetogenic drug, tissue levels of copper, zinc, iron and manganese were determined and compared to control animals. Increased quantities of hepatic copper, zinc and manganese, renal copper and zinc and plasma zinc were observed in the diabetic group. Intestinal, muscle and spleen contents of the metals were similar in control and diabetic rats. Elevated levels of zinc- and copper-metallothionein were found in liver and kidney of diabetic rats. The distribution of zinc among soluble proteins in the diabetic liver was also content of tissues, intracellular distribution of zinc and the quantity of zinc-and copper-metallothionein to normal levels. Pair-feeding copper, zinc, iron and manganese to diabetic and control groups demonstrated that the enhanced food consumption of the diabetic rat was not a significant factor in the observed accumulation of trace metals in liver and kidney. These data suggest that the hormonal imbalance characteristic of the insulin-dependent diabetic condition influences trace metal metabolism. These studies also demonstrate the usefulness of the streptozotocin-diabetic rat as an animal model for investigations concerning hormone-mediated regulation of trace metal metabolism.