Bradley A J, Stoddart D M
Department of Zoology, University of Tasmania, Hobart, Australia.
J Endocrinol. 1990 Nov;127(2):203-12. doi: 10.1677/joe.0.1270203.
The effects of cortisol, ACTH, adrenalin and insulin on indices of carbohydrate, fat and protein metabolism were investigated in the conscious marsupial sugar glider Petaurus breviceps. Short-term i.v. infusion of cortisol at dose rates of 0.02, 0.2 and 1.0 mg/kg per h caused the plasma glucose concentration to rise sharply from the normal range of 3.3-4.4 to 8.1-8.7 mmol/l at the end of the infusion period without significant alteration in plasma free fatty acid (FFA), amino acid or urea concentrations. Infusions of ACTH at dose rates of 0.02, 0.06 and 0.45 IU/kg per h caused a similar rise in plasma glucose concentration; however, this was now accompanied by an elevation in plasma FFA concentration, but again without significant changes in either plasma amino acid or urea concentrations. Infusion of adrenalin at 10 micrograms/kg per h caused an increase in the plasma concentrations of both glucose and FFA. Intravenous injections of 0.15 IU insulin/kg caused a rapid and marked decrease in the plasma glucose concentration within 30 min and an increase in the plasma free cortisol concentration. Associated with this change was a marked rise in the plasma concentration of both FFA and free cortisol. The rise in free cortisol was, however, significantly reduced by infusion of glucose. Pretreatment with five daily i.m. injections of 1 mg cortisol acetate/kg, which produced an increase in plasma free cortisol concentration to near the maximum of the physiological range, caused a marked reduction in insulin sensitivity. Cortisol pretreatment caused an increase in the plasma FFA and amino acid concentrations. Petaurus breviceps is highly sensitive to the metabolic effects of glucocorticoids and is similar in this respect to the brush-tailed possum Trichosurus vulpecula. The interactive effects between insulin and glucocorticoids on carbohydrate, fat and protein metabolism in Petaurus breviceps are similar to those shown by Trichosurus vulpecula and some eutherian mammals but contrast with the pattern described for two macropodid marsupials, the red kangaroo Macropus rufus and the quokka Setonix brachyurus.
在清醒的有袋动物蜜袋鼯（Petaurus breviceps）中，研究了皮质醇、促肾上腺皮质激素（ACTH）、肾上腺素和胰岛素对碳水化合物、脂肪和蛋白质代谢指标的影响。以每小时0.02、0.2和1.0毫克/千克的剂量率进行皮质醇的短期静脉输注，导致输注期结束时血浆葡萄糖浓度从3.3 - 4.4毫摩尔/升的正常范围急剧升至8.1 - 8.7毫摩尔/升，而血浆游离脂肪酸（FFA）、氨基酸或尿素浓度无显著变化。以每小时0.02、0.06和0.45国际单位/千克的剂量率输注ACTH，导致血浆葡萄糖浓度出现类似升高；然而，此时血浆FFA浓度也升高，但血浆氨基酸或尿素浓度同样无显著变化。以每小时10微克/千克的剂量输注肾上腺素，导致血浆葡萄糖和FFA浓度均升高。静脉注射0.15国际单位胰岛素/千克，在30分钟内导致血浆葡萄糖浓度迅速且显著降低，同时血浆游离皮质醇浓度升高。与此变化相关的是血浆FFA和游离皮质醇浓度均显著升高。然而，通过输注葡萄糖，游离皮质醇的升高显著降低。每天肌肉注射1毫克醋酸皮质醇/千克，连续注射五天进行预处理，使血浆游离皮质醇浓度升高至接近生理范围的最大值，导致胰岛素敏感性显著降低。皮质醇预处理使血浆FFA和氨基酸浓度升高。蜜袋鼯对糖皮质激素的代谢作用高度敏感，在这方面与帚尾袋貂（Trichosurus vulpecula）相似。胰岛素和糖皮质激素对蜜袋鼯碳水化合物、脂肪和蛋白质代谢的相互作用与帚尾袋貂和一些真兽类哺乳动物所表现的相似，但与两种袋鼠科有袋动物——红袋鼠（Macropus rufus）和短尾矮袋鼠（Setonix brachyurus）所描述的模式形成对比。
