EFFECT OF ZINC SUPPLEMENTATION ON METALLOTHIONEIN, COPPER, AND ZINC CONCENTRATION IN VARIOUS TISSUES OF COPPER-LOADED RATS

The present study was designed to investigate the effects of Zn admini stration on metallothionein concentrations in the liver, kidney, and i ntestine of copper-loaded rats. Male CD rats were fed a diet containin g 12 mg Cu and 67 mg Zn/kg body wt. They were divided into either acut e or chronic experimental protocols. Rats undergoing acute experiments received daily ip injections of either Cu (3 mg/kg body wt) or Zn (10 mg/kg body wt) for 3 d. Chronic experiments were carried out on rats receiving Cu ip injections on d 1, 2, 3, 10, 17, and 24, Cu injections plus a Zn-supplemented diet containing 5 g Zn/kg solid diet, or a Zn- supplemented diet alone. Rats injected Zn or Cu had increased MT conce ntrations in liver and kidney. Zn produced the most important effects and the liver was the most responsive organ. Rats fed a Zn-supplemente d diet had significantly higher MT concentrations in liver and intesti ne with respect to controls. Increased MT synthesis in the liver may c ontribute to copper detoxification; the hypothesis of copper entrapmen t in enterocytes cannot be confirmed.