Salem M A
Lutcher Brown Department of Biochemistry, Whittier Institute for Diabetes and Endocrinology, La Jolla, California 92037.
Endocrinology. 1988 Sep;123(3):1565-76. doi: 10.1210/endo-123-3-1565.
A naturally occurring pituitary peptide, human (h) GH-(1-43) potentiates insulin action. The present study has compared the effects of acute (30-60 min) and chronic (3-6 days) injections of synthetic hGH-(1-43), hGH, and insulin in normal, diabetic, hypophysectomized, and diabetic-hypophysectomized rats. Male rats (150-250 g) received injections of saline, insulin (50-200 mU), hGH (200 micrograms), or hGH-(1-43) (200-400 micrograms) with or without insulin. Hormone and glucose were injected simultaneously for glucose tolerance tests. Basal and insulin-stimulated [U-14C]glucose oxidation to 14CO2 in adipose tissue were measured in vitro after in vivo treatments; insulin release by isolated pancreatic islets was determined in vitro. Acute injections of hGH-(1-43) with insulin dramatically increased glucose clearance in diabetic (P less than 0.05) and hypophysectomized (P less than 0.01) rats. In diabetic-hypophysectomized rats acute injections of hGH-(1-43) significantly lowered the elevated basal blood glucose level (P less than 0.025) and stimulated [U-14C]glucose oxidation to 14CO2 in adipose tissue (P less than 0.05); it did not increase the glucose clearance rate during glucose administration. Chronic treatment of diabetic rats with hGH-(1-43) did not lower the elevated blood glucose level significantly, but it stimulated [U-14C]glucose oxidation to 14CO2 in adipose tissue; the oxidation was further stimulated by treatment with insulin. Chronic injections of hGH-(1-43) slightly lowered blood glucose levels in hypophysectomized rats (P less than 0.025) despite a diminished release in vitro of insulin from pancreatic islets (P less than 0.05). Therefore, these experiments show hGH-(1-43) to be an insulin potentiator that increases insulin-stimulated glucose clearance and glucose oxidation without an increase in insulin secretion, and they suggest that the peptide may have a physiological role in regulating carbohydrate metabolism.
一种天然存在的垂体肽，人（h）GH-(1 - 43)可增强胰岛素作用。本研究比较了在正常、糖尿病、垂体切除及糖尿病垂体切除大鼠中，急性（30 - 60分钟）和慢性（3 - 6天）注射合成的hGH-(1 - 43)、hGH和胰岛素的效果。雄性大鼠（150 - 250克）接受生理盐水、胰岛素（50 - 200 mU）、hGH（200微克）或hGH-(1 - 43)（200 - 400微克）注射，注射时可搭配或不搭配胰岛素。为进行葡萄糖耐量试验，激素和葡萄糖同时注射。在体内处理后，体外测量脂肪组织中基础及胰岛素刺激下的[U - 14C]葡萄糖氧化为14CO2的情况；体外测定分离的胰岛释放胰岛素的情况。急性注射hGH-(1 - 43)与胰岛素可显著增加糖尿病大鼠（P < 0.05）和垂体切除大鼠（P < 0.01）的葡萄糖清除率。在糖尿病垂体切除大鼠中，急性注射hGH-(1 - 43)可显著降低升高的基础血糖水平（P < 0.025），并刺激脂肪组织中[U - 14C]葡萄糖氧化为14CO2（P < 0.05）；在给予葡萄糖期间，它并未提高葡萄糖清除率。用hGH-(1 - 43)对糖尿病大鼠进行慢性治疗并未显著降低升高的血糖水平，但它刺激了脂肪组织中[U - 14C]葡萄糖氧化为14CO2；胰岛素治疗可进一步刺激这种氧化。尽管慢性注射hGH-(1 - 43)使垂体切除大鼠体外胰岛胰岛素释放减少（P < 0.05），但仍使其血糖水平略有降低（P < 0.025）。因此，这些实验表明hGH-(1 - 43)是一种胰岛素增强剂，可增加胰岛素刺激的葡萄糖清除率和葡萄糖氧化，而不增加胰岛素分泌，并且提示该肽可能在调节碳水化合物代谢中具有生理作用。
