Photoperiod-dependent and -independent regulation of melatonin receptors in the forebrain of songbirds
Photoperiod-dependent and -independent regulation of melatonin receptors in the forebrain of songbirds
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DOI：
10.1046/j.1365-2826.2000.00523.x
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发表时间：
2000-08-01
影响因子：
3.2
通讯作者：
Ball, GF
中科院分区：
文献类型：
--
作者：
Bentley, GE;Ball, GF
褪黑激素最近被确定为发挥作用，在微调性腺类固醇激素的影响，在调节季节性神经可塑性内的端脑歌曲控制系统的欧洲椋鸟。本研究探讨了可能的季节性调节褪黑激素受体（MelR）内的八哥歌曲控制系统，在存在或不存在的性腺类固醇。大脑样本从光敏椋鸟暴露于短天，光刺激椋鸟暴露于长天，光不应椋鸟也暴露于长天。每种情况下包含一组性腺完整的鸟类和一组阉割的鸟类。通过（125-）碘褪黑激素（IMEL）受体放射自显影术在体外评估褪黑激素受体分布。MelR的分布与其它鸣禽相似。然而，有一个显着的下调MelR的歌曲控制核X区的完整和阉割的光刺激的鸟类在长的日子相比，他们的photorefractory的同行在相同的长的日子和短的一天组。MelR的下调发生独立的性腺类固醇。然而，叠加在光刺激过程中MelR下调的一般模式上，当存在性腺类固醇时，在X区的内侧细分中观察到IMEL结合。MelR在短的繁殖季节在X区下调的歌曲控制系统的季节性调节的影响。随后上调MelR的鸟类成为光不应性，在没有任何变化的光周期，性腺类固醇或褪黑激素信号是第一个描述的光周期无关的调节MelR在成年人的任何脊椎动物类。
Melatonin was recently identified as playing a role in fine-tuning the effects of gonadal steroids in the regulation of seasonal neuroplasticity within the telencephalic song control system of European starlings. The present study investigated possible seasonal regulation of melatonin receptors (MelR) within the starling song control system, in the presence or absence of gonadal steroids. Brains were sampled from photosensitive starlings exposed to short days, photostimulated starlings exposed to long days and photorefractory starlings also exposed to long days. Each condition contained a group of gonad-intact birds and a group of castrated birds. Melatonin receptor distribution was assessed in vitro by (125-)iodomelatonin (IMEL) receptor autoradiography. In general, MelR distribution was similar to that described in other songbird species. However, there was a striking downregulation of MelR in the song control nucleus Area X of intact and castrated photostimulated birds on long days compared to their photorefractory counterparts on the same long days and to the short-day groups. Downregulation of MelR occurred independently of gonadal steroids. Nevertheless, superimposed on this general pattern of MelR downregulation during photostimulation, IMEL binding was observed in a medial subdivision of Area X when gonadal steroids were present. Downregulation of MelR in Area X during the short breeding season has implications for seasonal regulation of the song control system. Subsequent upregulation of MelR as birds become photorefractory, in the absence of any change in photoperiod, gonadal steroids or melatonin signal is the first description of photoperiod-independent regulation of MelR in adults of any vertebrate class.