Metabolic effects of high doses of manganese in rats.

The effects of acute manganese (Mn) toxicity on tissue manganese concentrations and on plasma glucose levels were investigated in adult male Sprague-Dawley rats. Manganese injection in all tissues analyzed was reflected by a significant increase in Mn concentration that was transitory. Changes in the molecular localization of Mn in liver following injection include both increases in protein-bound Mn and low molecular weight Mn complexes. A rapid, dose-responsive rise in blood glucose followed Mn injection, whereas circulating insulin levels decreased after injection. These data show that acute changes in tissue Mn levels can have a pronounced effect on carbohydrate metabolism. [ABSTRACT FROM AUTHOR]