Laboratory of Reproductive Neuroendocrinology, Department of Integrative Biology, University of California at Berkeley, Berkeley, CA 94720-3140, USA.
Horm Behav. 2013 May;63(5):829-35. doi: 10.1016/j.yhbeh.2012.11.015. Epub 2012 Nov 29.
There are dense populations of melatonin receptors in large areas of the songbird brain, in particular in the visual system and the song control system. Melatonin has therefore been implicated in neuroplasticity of the song control system. Previously we demonstrated large changes in activity of melatonin receptor in Area X, a forebrain song control nucleus involved in song learning and production. In a laboratory environment, melatonin receptor activity was down-regulated in male and female European starlings during photostimulation (a simulated breeding season). The functional significance of this large change in Area X is unclear, so we sought to elucidate it by tracking melatonin receptor activity in male and female starlings housed in a semi-natural environment and permitted to breed. Males and females all exhibited high melatonin receptor activity in Area X during short days at the start of the breeding season, and maintained this high activity during photostimulation until females laid eggs. At this point the females down-regulated melatonin receptor activity in Area X, whereas the males maintained high activity until later on in the breeding season. Mel 1b was the most abundantly expressed of the 3 known melatonin receptor subtypes in Area X. There was a positive correlation between the expression of Mel 1b and the transcription factor ZENK, indicating that high melatonin receptor expression is correlated with high activity of Area X. Overall, we observed a gradual termination of activity in Area X as the breeding season progressed, but the timing of termination was different between the sexes.
在鸟类大脑的大片区域，特别是在视觉系统和歌唱控制系统中，存在着密集的褪黑素受体。因此，褪黑素被认为与歌唱控制系统的神经可塑性有关。之前我们已经证明，在参与鸣唱学习和产生的前脑歌唱控制核区 X 中，褪黑素受体的活性发生了很大的变化。在实验室环境中，雄性和雌性欧洲椋鸟在光刺激（模拟繁殖季节）期间，其 X 区的褪黑素受体活性下调。X 区这种巨大变化的功能意义尚不清楚，因此我们试图通过在半自然环境中饲养并允许其繁殖的雄性和雌性椋鸟中追踪褪黑素受体活性来阐明这一点。在繁殖季节开始时的短日期间，雄性和雌性椋鸟的 X 区都表现出很高的褪黑素受体活性，并且在光刺激期间保持这种高活性，直到雌性产卵。此时，雌性的 X 区褪黑素受体活性下调，而雄性则在繁殖季节后期才维持高活性。在 X 区，Mel 1b 是已知的 3 种褪黑素受体亚型中表达最丰富的一种。Mel 1b 的表达与转录因子 ZENK 呈正相关，这表明高褪黑素受体表达与 X 区的高活性相关。总的来说，我们观察到随着繁殖季节的进行，X 区的活动逐渐终止，但终止的时间在两性之间不同。
