Manganese deficiency and toxicity: effects on carbohydrate metabolism in the rat.
Manganese deficiency and toxicity: effects on carbohydrate metabolism in the rat.
复制标题
锰缺乏和毒性：对大鼠碳水化合物代谢的影响。
作者：
L. Hurley;C. L. Keen;Deborah L. Baly
虽然锰缺乏和锰中毒都有病理后果，潜在的生化病变还没有得到很好的定义。锰参与碳水化合物代谢;无论是缺乏或过量都会导致碳水化合物代谢异常。临床研究表明，慢性锰中毒患者在葡萄糖负荷后会发生低血糖。已经发表了一份关于糖尿病患者的报告，该患者对口服锰有反应，血糖持续下降。喂饲锰缺乏饮食的大鼠对口服葡萄糖负荷的反应具有糖尿病型葡萄糖耐量曲线。缺锰动物胰腺对葡萄糖刺激的胰岛素释放低于对照组。胰岛素输出减少发生在胰岛素输出的第一阶段（释放储存的激素）和第二阶段（释放储存和新合成的激素）。因此，膳食锰缺乏可导致胰岛素产生异常，产生受损的碳水化合物代谢。锰毒性也影响碳水化合物代谢。大鼠腹腔注射高水平的锰显示出快速的高血糖症和低胰岛素血症，随后是反应性低血糖症。血糖和血胰岛素水平的变化与肝脏和胰腺锰浓度的变化相关，这表明锰对碳水化合物代谢的一些影响可能是由于对胰岛素释放和代谢的直接影响。
Although manganese deficiency and manganese toxicity both have pathological consequences, the underlying biochemical lesions have not been well defined. Manganese is involved in carbohydrate metabolism; either deficiency or excess results in abnormal carbohydrate metabolism. Clinical studies have shown that patients with chronic manganism have hypoglycemia following a glucose load. One report has been published of a diabetic patient who responded to oral manganese with a consistent drop in blood glucose. Rats fed a manganese deficient diet respond to an oral glucose load with a diabetic type of glucose tolerance curve. Insulin release from the pancreas of manganese deficient animals in response to a glucose stimulus is lower than controls. Reduced insulin output occurs in both the first phase (release of stored hormone) and second phase (release of stored and newly synthesized hormone) of insulin output. Thus dietary manganese deficiency can result in abnormal insulin production producing impaired carbohydrate metabolism. Manganese toxicity also affects carbohydrate metabolism. Rats given intraperitoneal injections of high levels of manganese show a rapid hyperglycemia and hypoinsulinemia, followed by a reactionary hypoglycemia. The changes in blood glucose and blood insulin levels correlated with changes in liver and pancreatic manganese concentrations, suggesting that some of the effects of manganese on carbohydrate metabolism may be due to a direct effect on insulin release and gluconeogenesis.