Structural and Functional Evolution of the Pineal Melatonin System in Vertebrates
Structural and Functional Evolution of the Pineal Melatonin System in Vertebrates
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DOI：
10.1111/j.1749-6632.2009.04435.x
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发表时间：
2009-01-01
期刊：
影响因子：
--
通讯作者：
Boeuf, Gilles
中科院分区：
文献类型：
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作者：
Falcon, Jack;Besseau, Laurence;Boeuf, Gilles
在大多数物种中，每日节律是由光周期周期同步的。它们是由昼夜节律系统产生的，该系统由起搏器、通向这个时钟的携带路径以及一个或多个输出信号组成。在脊椎动物中，松果体器官产生的褪黑素就是其中之一。这种守时荷尔蒙的产生在夜间高，白天低。尽管这是一种保存完好的模式，但从早期的脊椎动物到哺乳动物，光周期信息控制节奏的途径已经发生了深刻的变化。光周期控制在鱼和蛙中是直接的，在哺乳动物中是间接的。在前者中，在松果体、视网膜、可能还有大脑的感光细胞中发现了有趣的环状系统，从而形成了褪黑素可能是荷尔蒙同步器的网络。在后者中，昼夜节律系统的三个要素是分散的：光接收单位在眼睛中，时钟在下丘脑的视交叉上核，褪黑素产生单位在松果体细胞中。在蜥蜴身上观察到的是中间情况。在芳基烷基胺N-乙酰基转移酶(AANAT)的水平上也存在差异，该酶负责褪黑激素的日变化。与四足动物不同，硬骨鱼AANAT是复制的，并显示组织特异性表达；此外，松果体AANAT是特殊的-它以物种特有的方式对温度做出反应，这反映了鱼类的生态生理偏好。本文综述了脊椎动物褪黑素产生系统进化的解剖、结构和分子方面的研究进展。
In most species daily rhythms are synchronized by the photoperiodic cycle. They are generated by the circadian system, which is made of a pacemaker, an entrainment pathway to this clock, and one or more output signals. In vertebrates, melatonin produced by the pineal organ is one of these outputs. The production of this time-keeping hormone is high at night and low during the day. Despite the fact that this is a well-preserved pattern, the pathways through which the photoperiodic information controls the rhythm have been profoundly modified from early vertebrates to mammals. The photoperiodic control is direct in fish and frogs and indirect in mammals. In the former, fun circathan systems are found in photoreceptor cells of the pineal organ, retina, and possibly brain, thus forming a network where melatonin could be a hormonal synchronizer. In the latter, the three elements of a circadian system are scattered: the photoreceptive units are in the eyes, the clocks are in the suprachiasmatic nuclei of the hypothalamus, and the melatonin-producing units are in the pineal cells. Intermediate situations are observed in sauropsids. Differences are also seen at the level of the arylalkylamine N-acetyltransferase (AANAT), the enzyme responsible for the daily variations in melatonin production. In contrast to tetrapods, teleost fish AANATs are duplicated and display tissue-specific expression; also, pineal AANAT is special-it responds to temperature in a species-specific manner, which reflects the fish ecophysiological preferences. This review summarizes anatomical, structural, and molecular aspects of the evolution of the melatonin-producing system in vertebrates.