Koch Kristin A, Wingfield John C, Buntin John D
Department of Biological Sciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 5320l, USA.
Horm Behav. 2002 Feb;41(1):9-21. doi: 10.1006/hbeh.2001.1726.
These studies explored the possibility that glucocorticoids promote parental care in ring doves by mediating, at least in part, the pronounced increase in food consumption that parent doves exhibit while provisioning their young. Plasma concentrations of the endogenous glucocorticoid corticosterone were found to be significantly higher in breeding females during the posthatching phase than during the incubation period. These differences were not observed in male breeding partners, but sex differences in daily activity rhythms are well documented in breeding doves, and blood sampling at different times of day would be required to adequately characterize the pattern of corticosterone in males during these breeding stages. In studies on nonbreeding doves, twice-daily intracerebroventricular (icv) injections of the synthetic glucocorticoid dexamethasone (DEX) increased food intake by 25-50% in both sexes, and further studies in males revealed that the increase was directly related to the dose of DEX administered. The highest dose of DEX given icv (1.0 microg/day) was not effective in stimulating feeding when given systemically, thereby suggesting that the hyperphagic action of DEX is exerted directly on the central nervous system. The icv infusion of the selective glucocorticoid receptor antagonist RU38486 blocked the hyperphagic effects of twice-daily icv injections of DEX in both sexes. Collectively, these data support the hypothesis that corticosterone contributes to the parental hyperphagia exhibited by breeding doves during the posthatching period. They also suggest that these orexigenic effects are mediated in part by CNS binding sites that resemble mammalian glucocorticoid receptors.
这些研究探讨了糖皮质激素促进环鸽亲代抚育行为的可能性，即糖皮质激素至少部分介导了亲鸽在育雏时食物摄入量的显著增加。研究发现，育雏期雌性环鸽血浆中内源性糖皮质激素皮质酮的浓度在孵化后期显著高于孵化期。在雄性配偶中未观察到这些差异，但繁殖期鸽子的日常活动节律存在性别差异，需要在一天中的不同时间进行采血，才能充分描述这些繁殖阶段雄性鸽子的皮质酮模式。在对非繁殖期鸽子的研究中，每天两次脑室内注射合成糖皮质激素地塞米松（DEX），雌雄鸽子的食物摄入量均增加了25%-50%，对雄性鸽子的进一步研究表明，这种增加与所注射的DEX剂量直接相关。脑室内注射最高剂量的DEX（1.0微克/天）经全身给药时对刺激进食无效，这表明DEX的摄食促进作用直接作用于中枢神经系统。脑室内注入选择性糖皮质激素受体拮抗剂RU38486可阻断每天两次脑室内注射DEX对雌雄鸽子摄食促进作用的影响。总体而言，这些数据支持了皮质酮有助于繁殖期鸽子在孵化后期出现亲代摄食亢进的假说。它们还表明，这些促食欲作用部分是由类似于哺乳动物糖皮质激素受体的中枢神经系统结合位点介导的。
