Tsai A, Cowan M R, Johnson D G, Brannon P M
Department of Nutrition, University of Arizona, Tucson 85721.
Am J Physiol. 1994 Oct;267(4 Pt 1):G575-83. doi: 10.1152/ajpgi.1994.267.4.G575.
Although insulin has been proposed to mediate the dietary regulation of pancreatic amylase, its interaction with diet in the regulation of amylase and lipase is not well understood and was examined in diabetic rats fed diets high in carbohydrate (HC), protein (HP), or fat (HF) and treated with insulin. Diabetes, independent of diet, decreased amylase content (97%; P < 0.0001) and mRNA (90%; P < 0.0001), but insulin only restored amylase content and mRNA to respective dietary control values. Diabetes, independent of diet, also increased lipase mRNA 1.6-fold (P < 0.004) but interacted (P < 0.0003) with diet on lipase content, resulting in opposite effects in HC- (increased 202%) and HF-diabetic rats (decreased 40%). Insulin partially restored lipase content and mRNA to respective dietary control values. Diet, independent of diabetes, regulated amylase content (P < 0.0001) and mRNA (P < 0.0003), which were three- to fourfold greater in HC- than in HF-fed rats, and lipase content (P < 0.001) and mRNA [rat pancreatic lipase 1 (rPL-1), P < 0.04; rPL-3, P < 0.0001], which were 1.8-fold greater in HF- than in HC- or HP-fed rats. Insulin failed to stimulate maximal amylase gene expression in HP- or HF-fed diabetic rats, suggesting that it is necessary, but not sufficient, for this dietary regulation. Differential regulation of lipase activity and mRNA by diet and insulin raises the possibility that lipase gene expression is regulated by a complex interaction of diet and insulin.
尽管有观点认为胰岛素介导了饮食对胰腺淀粉酶的调节作用，但其在淀粉酶和脂肪酶调节过程中与饮食的相互作用尚未完全明确。本研究对喂食高碳水化合物（HC）、高蛋白（HP）或高脂肪（HF）饮食并接受胰岛素治疗的糖尿病大鼠进行了检测。糖尿病本身（不考虑饮食因素）会使淀粉酶含量降低97%（P < 0.0001），mRNA水平降低90%（P < 0.0001），但胰岛素仅能将淀粉酶含量和mRNA水平恢复至各自饮食对照组的值。糖尿病本身（不考虑饮食因素）还会使脂肪酶mRNA水平增加1.6倍（P < 0.004），但在脂肪酶含量方面与饮食存在相互作用（P < 0.0003），导致HC组糖尿病大鼠脂肪酶含量增加202%，而HF组糖尿病大鼠脂肪酶含量降低40%。胰岛素可部分将脂肪酶含量和mRNA水平恢复至各自饮食对照组的值。饮食本身（不考虑糖尿病因素）可调节淀粉酶含量（P < 0.0001）和mRNA水平（P < 0.0003），HC组大鼠的淀粉酶含量和mRNA水平比HF组大鼠高3至4倍；同时也可调节脂肪酶含量（P < 0.001）和mRNA水平[大鼠胰腺脂肪酶-1（rPL-1），P < 0.04；rPL-3，P < 0.0001]，HF组大鼠的脂肪酶含量和mRNA水平比HC组或HP组大鼠高1.8倍。胰岛素无法刺激HP组或HF组糖尿病大鼠的淀粉酶基因达到最大表达水平，这表明胰岛素对于这种饮食调节是必要的，但并不充分。饮食和胰岛素对脂肪酶活性和mRNA的差异调节提示，脂肪酶基因表达可能受饮食和胰岛素复杂相互作用的调控。
