Sex variation in dietary regulation of insulin receptors in man.
Hyperinsulinemia is associated with decreased insulin sensitivity and decreased binding of insulin to specific cellular receptors. In cells growth in culture, insulin directly decreases the concentration of its own receptor. Therefore, a negative feedback system has been proposed in which insulin sensitivity is regulated by insulin itself. In the present study, we investigated if nutritional factors could also regulate insulin binding to circulating monocytes in normal volunteers. The caloric content of their diet was kept constant and was calculated to maintain constant body weight. The diet consisted of 45% carbohydrate for the first 4 days and 75% carbohydrate for the next 7 days. In men, the high carbohydrate diet was associated with a 37% (P < 0.01) fall in insulin binding without change in serum or urinary levels of insulin. Despite the fall in insulin binding, no rise in serum glucose or free fatty acids was observed. In women, the high carbohydrate diet was not associated with any changes in insulin levels, insulin binding, glucose or fatty acids. We conclude that dietary regulation of insulin receptors in normal weight subjects is sex specific. Carbohydrate loading can decrease insulin binding in normal men by a mechanism that is not dependent on hyperinsulinemia.
D000328:Adult; D001835:Body Weight; D002478:Cells, Cultured; D004040:Dietary Carbohydrates / Q000494:pharmacology*; D005246:Feedback; D005260:Female; D006801:Humans; D006946:Hyperinsulinism / Q000097:blood; D007328:Insulin / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D009000:Monocytes / Q000378:metabolism*; D011972:Receptor, Insulin / Q000378:metabolism; D012737:Sex Factors
D004040:Dietary Carbohydrates; D007328:Insulin; D011972:Receptor, Insulin