Quan Z Y, Walser M
Department of Pharmacology and Molecular Sciences, Johns Hopkins University, School of Medicine, Baltimore, MD.
Am J Clin Nutr. 1992 Mar;55(3):695-700. doi: 10.1093/ajcn/55.3.695.
Adrenalectomized rats were implanted with pellets containing corticosterone in proportions varying from 0% to 100%, plus cholesterol. Stable concentrations of plasma corticosterone resulted, varying from subnormal (A) to physiologic (B) to supraphysiologic (C). When food was ingested ad libitum, weight gain was maximal in B at plasma corticosterone concentrations of 0.14-0.20 mumol/L; weight loss occurred in C, despite higher food intake. Even when rats had constant limited food intake, weight gain and positive nitrogen balance were significantly reduced in A compared with B because fecal nitrogen rose significantly and the retention of absorbed nitrogen for growth decreased. In C, weight decreased despite constant intake, and nitrogen balance became negative because urinary nitrogen increased markedly. We conclude that glucocorticoid insufficiency reduces nitrogen balance by impairing intestinal absorption of dietary protein and the utilization of absorbed nitrogen, whereas glucocorticoid excess reduces nitrogen balance by augmenting urinary nitrogen despite constant nitrogen intake.
对肾上腺切除的大鼠植入含有皮质酮的药丸，皮质酮比例从0%到100%不等，再加上胆固醇。由此产生了稳定的血浆皮质酮浓度，范围从低于正常水平（A）到生理水平（B）再到高于生理水平（C）。当大鼠随意进食时，血浆皮质酮浓度为0.14 - 0.20 μmol/L时，B组的体重增加最大；C组尽管食物摄入量更高，但仍出现体重减轻。即使大鼠的食物摄入量持续受限，与B组相比，A组的体重增加和正氮平衡仍显著降低，因为粪便氮显著增加，而用于生长的吸收氮保留量减少。在C组中，尽管摄入量恒定，但体重仍下降，且氮平衡变为负值，因为尿氮显著增加。我们得出结论，糖皮质激素不足通过损害膳食蛋白质的肠道吸收和吸收氮的利用来降低氮平衡，而糖皮质激素过量则通过在氮摄入量恒定的情况下增加尿氮来降低氮平衡。
