Westerhof I, Van den Brom W E, Mol J A, Lumeij J T, Rijnberk A
Department of Clinical Sciences of Companion Animals, Faculty of Veterinary Medicine and Sciences, University of Utrecht, The Netherlands.
Avian Dis. 1994 Jul-Sep;38(3):435-45.
The sensitivity of the hypothalamic-pituitary-adrenal system in pigeons (Columba livia domestica) to glucocorticoid feedback was studied after single intravenous administration of dexamethasone (500, 100, 50, 10, 5, 1, 0.5, and 0.1 micrograms/kg), cortisol (15,000, 3000, 1500, 300, 150, 30, 15, and 3 micrograms/kg), and prednisolone (3500, 700, 350, 70, 35, 7, 3.5, 0.7, and 0.35 micrograms/kg). Dose responses, the threshold doses, and the onset of maximum suppression were determined by measuring plasma corticosterone concentrations around the expected peak of plasma corticosterone in pigeons kept on a shifted-light regimen. At 52 hr following the highest dose of dexamethasone, and at 48 hr following the highest doses of cortisol and prednisolone, plasma corticosterone concentrations were similar to the initial values and to the control values. Following the minimum doses that resulted in suppression of the normal diurnal variation in plasma corticosterone concentration (0.5 microgram dexamethasone/kg, 15 micrograms cortisol/kg, and 0.7 microgram prednisolone/kg), plasma corticosterone concentrations were similar to values of the control group and to initial values within 24 hr. The onset of suppression of plasma corticosterone concentrations was between 30 and 60 min following 1 microgram dexamethasone/kg, 7 micrograms prednisolone/kg, or 30 micrograms cortisol/kg. Suppression was greatest at 60 min following prednisolone and cortisol administration, and at 90 min following dexamethasone administration. It is concluded that the hypothalamic-pituitary-adrenal system of pigeons reacts to exogenous glucocorticoids by early delayed feedback, is more sensitive to suppression by glucocorticoids than that of mammals, and is suppressed for the longest time by dexamethasone. These observations indicate that some of the side effects of glucocorticoid therapy are likely to be at least as frequent and as severe in birds as in mammals.
在对家鸽（Columba livia domestica）单次静脉注射地塞米松（500、100、50、10、5、1、0.5和0.1微克/千克）、皮质醇（15000、3000、1500、300、150、30、15和3微克/千克）以及泼尼松龙（3500、700、350、70、35、7、3.5、0.7和0.35微克/千克）后，研究了家鸽下丘脑 - 垂体 - 肾上腺系统对糖皮质激素反馈的敏感性。通过测量处于光照周期改变饲养条件下的家鸽血浆皮质酮预期峰值附近的血浆皮质酮浓度，来确定剂量反应、阈值剂量以及最大抑制的起始时间。在地塞米松最高剂量给药后52小时，以及皮质醇和泼尼松龙最高剂量给药后48小时，血浆皮质酮浓度与初始值及对照值相似。在导致血浆皮质酮浓度正常昼夜变化受到抑制的最小剂量（地塞米松0.5微克/千克、皮质醇15微克/千克和泼尼松龙0.7微克/千克）给药后，血浆皮质酮浓度在24小时内与对照组值及初始值相似。在给予1微克/千克地塞米松、7微克/千克泼尼松龙或30微克/千克皮质醇后，血浆皮质酮浓度抑制的起始时间在30至60分钟之间。在给予泼尼松龙和皮质醇后60分钟以及地塞米松后90分钟时抑制作用最大。得出的结论是，家鸽的下丘脑 - 垂体 - 肾上腺系统通过早期延迟反馈对外源糖皮质激素作出反应，对糖皮质激素抑制作用的敏感性高于哺乳动物，并且被地塞米松抑制的时间最长。这些观察结果表明，糖皮质激素治疗的一些副作用在鸟类中可能至少与在哺乳动物中一样频繁和严重。
