Effect of manganese deficiency on insulin secretion and carbohydrate homeostasis in rats.
The effects of manganese (Mn) deficiency on carbohydrate metabolism in the Sprague-Dawley rat were investigated. Oral glucose tolerance tests were performed on offspring from Mn-sufficient female rats fed 45 micrograms Mn per gram diet (C-C), offspring from Mn-deficient female rats fed 1 microgram Mn per gram diet (D1-D1) and rats not exposed to Mn deficiency in utero but fed D1 diet from weaning to maturity (D1). Mn-deficient rats, D1 and D1-D1, had significantly lower concentrations of Mn in liver, kidney, heart and pancreas than controls. D1-D1 rats responded with a diabetic type of glucose tolerance curve when given oral glucose. Insulin levels of D1-D1 rats were not commensurate with their high glucose levels. Measurements made by using an isolated perfused-pancreas preparation indicate that insulin output due to release of stored hormone was 76% of control levels in D1-D1 rats. This suggests either lower insulin stores or impaired release of insulin in D1-D1 rats. Second phase insulin release was also significantly lower in D1-D1 rats than in controls. Pancreatic insulin content was 63% of control levels in D1-D1 rats, further supporting the idea of lower insulin stores in Mn-deficient rats. No differences in plasma glucose levels were observed between D1 rats and controls after an oral-glucose load. These findings indicate that dietary Mn deficiency can result in impaired insulin secretion producing impaired carbohydrate metabolism; however, the timing of the deficiency may be a critical factor in the expression of this abnormality.
D000818:Animals; D001786:Blood Glucose; D005260:Female; D005947:Glucose / Q000378:metabolism*; D006706:Homeostasis; D007328:Insulin / Q000097:blood / Q000378:metabolism*; D000078790:Insulin Secretion; D007515:Islets of Langerhans / Q000378:metabolism; D008297:Male; D008345:Manganese / Q000172:deficiency* / Q000378:metabolism; D008431:Maternal-Fetal Exchange; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D014018:Tissue Distribution; D014131:Trace Elements / Q000378:metabolism
D001786:Blood Glucose; D007328:Insulin; D014131:Trace Elements; D008345:Manganese; D005947:Glucose