Molecular characterization of the long-day response in the soay sheep, a seasonal mammal
Molecular characterization of the long-day response in the soay sheep, a seasonal mammal
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DOI：
10.1016/j.cub.2004.01.057
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发表时间：
2004-02-17
期刊：
影响因子：
9.2
通讯作者：
Lincoln, G
中科院分区：
文献类型：
--
作者：
Hazlerigg, DG;Andersson, H;Lincoln, G
在哺乳动物中，季节性计时取决于反映夜长/昼长的夜间褪黑激素信号的产生[1]。为了理解褪黑激素信号解码的机制，我们研究了Soay绵羊催乳素分泌的光周期控制，这是通过垂体结节部的褪黑激素反应细胞介导的[2]。我们证明，时钟基因隐花色素1（Cry 1），周期1（Per 1），和RevErbalpha的峰值表达的阶段，迅速响应改变褪黑激素分泌后，从短到长的日子。Cry 1被褪黑素激活，形成分子解码器的黄昏部分，而Per 1在黎明时的表达反映了褪黑素分泌的抵消。Cry 1-Per 1间期在第一个漫长的一天立即调整褪黑激素信号，并且在24小时内随后增加催乳素分泌。峰值RevErbalpha表达的时间也响应于由于改变的褪黑激素分泌而转换为长日照，但不会立即重置为夹带的长日照状态。这些数据表明，褪黑激素对时钟基因表达的影响是神经内分泌反应中的关键事件，结节部细胞可以充当分子日历，携带一种形式的“光周期记忆”。"
In mammals, seasonal timekeeping depends on the generation of a nocturnal melatonin signal that reflects nightlength/daylength [1]. To understand the mechanisms by which the melatonin signal is decoded, we studied the photoperiodic control of prolactin secretion in Soay sheep, which is mediated via melatonin responsive cells in the pars tuberalis of the pituitary [2]. We demonstrate that the phases of peak expression of the clock genes Cryptochrome1 (Cry1), Period1 (Per1), and RevErbalpha respond acutely to altered melatonin secretion after a switch from short to long days. Cry1 is activated by melatonin onset, forming the dusk component of the molecular decoder, while Per1 expression at dawn reflects the offset of melatonin secretion. The Cry1-Per1 interval immediately adjusts to the melatonin signal on the first long day, and this is followed within 24 hr by an increase in prolactin secretion. The timing of peak RevErbalpha expression also responds to a switch to long days due to altered melatonin secretion but does not immediately reset to an entrained long-day state. These data suggest that effects of melatonin on clock gene expression are pivotal events in the neuroendocrine response and that pars tuberalis cells can act as molecular calendars, carrying a form of "photoperiodic memory."