Mechanism of glucose intolerance induced by a low-carbohydrate diet

在这项研究中，我们阐明了低碳水化合物（LC）饮食诱导葡萄糖耐受不良的机制。我们研究了LC饮食必须消耗多长时间才能损害大鼠的葡萄糖耐量，以及胰岛素分泌和胰岛素敏感性是否受到饮食诱导的游离脂肪酸（cFEA）水平增加的影响。在随机交叉设计中，对饲喂对照饲料（碳水化合物6050或碳水化合物1050饲料）1,3或7天的雄性Wistar大鼠进行腹腔葡萄糖耐量试验，并在饲喂对照饲料和LC饲料3天的大鼠中分离胰岛中测量胰岛素释放。在244i培养期间，还检测了暴露于棕榈酸（PA）的胰岛的胰岛素分泌。通过静脉注射胰岛素耐量试验，对喂食LC日粮3天的大鼠和静脉注射与pa融合24小时的大鼠进行全身胰岛素敏感性测定。葡萄糖耐量在食用LC日粮3天和7天后受损；7天后损伤更严重。糖耐量损伤伴随着空腹血浆游离脂肪酸水平的升高。葡萄糖刺激的胰岛素分泌在LC喂养3天后显著减少。对照组大鼠胰岛暴露于PA后，葡萄糖刺激的胰岛素分泌受损。LC喂养3天后，大鼠出现胰岛素抵抗，静脉注射PA降低了大鼠全身胰岛素敏感性。大鼠糖耐量下降可能与胰岛素分泌和胰岛素敏感性降低有关，也可能与LC日粮使血浆游离脂肪酸水平升高有关。

In this study, we clarified the mechanism of glucose intolerance induced by a low-carbohydrate (LC) diet. We examined how long a LC diet must be consumed in order to impair glucose tolerance in rats, and whether insulin secretion and insulin sensitivity are affected by the increased level of free fatty acids cFEA) induced by the diet. Intraperitoneal glucose tolerance tests were performed onmale Wistar rats that were fed a control diet (carbohydrate 6050 or aLC (carbohydrate 1050 diet for 1, 3, or 7 day(s) in a randomized crossover desiga Insulin release was measured in pancreatic islets isolated from rats fed control and LC diets for 3 days. Insulin secretion was also examined in islets exposed to palmitic acid (PA) during 244i culture. Whole body insulin sensitivity was measured by an intravenous insulin tolerance test in rats fed LC diet for 3 days or in rats intravenously in fused withPA for 24 h. Glucose tolerancewas impaired after 3 and 7 days of consuming a LC diet ; the impairment was more severe after 7 days. The glucose tolerance impairment was accompanied by a rise in the fasting plasma FFA level. Glucose-stimulated insulin secretion was significantly reduced in pancreatic islets from rats fed LC diet for 3 days. Exposure of control rat islets to PA impaired glucose-stimulated insulin secretion Rats fed LC diet for 3 days developed insulin resistance inviva Intravenous PA infusion into rats decreased thewhole body insulin sensitivity. Feeding rats a LC diet for 3 days impaired glucose tolerance The impairment may be induced by a decrease in both insulin secretion and insulin sensitivity, \rtiich may be caused by the increased plasma FFA level due to the LC diet.