Zinc Supplementation Attenuates Insulin Secretory Activity in Pancreatic Islets of the ob/ob Mouse

The purpose of this study was to establish whether a relationship may exist between the hyperinsulinemia, the exaggerated insulin secretion, and the resistance to insulin characteristic of the obese-hyperglycemic syndrome and the zinc status of the ob/ob mouse. To this end, mice were given control and zinc-supplemented diets, and the effects of zinc supplementation on insulin secretion in vivo and in vitro as well as on glucose tolerance were studied. These data were compared with those obtained with oxytetracycline treatment, which is known to ameliorate the insulin sensitivity and glucose tolerance of these animals. The levels of zinc were measured in several tissues of lean and obese mice and the results show that zinc supplementation attenuated the exaggerated insulin secretion in vivo and in vitro without improving the tolerance to glucose. Zinc levels were significantly higher in the tissues of the obese than of the lean mice, with the exception of bone and pancreas. The results suggest a maldistribution of zinc in the tissues of the obese mouse.