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首页> 外文期刊>Frontiers in neuroendocrinology >Human pineal physiology and functional significance of melatonin.
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Human pineal physiology and functional significance of melatonin.

机译：褪黑素对人体的松果体生理和功能意义。

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Descriptions of the pineal gland date back to antiquity, but its functions in humans are still poorly understood. In both diurnal and nocturnal vertebrates, its main product, the hormone melatonin, is synthesized and released in rhythmic fashion, during the dark portion of the day-night cycle. Melatonin production is controlled by an endogenous circadian timing system and is also suppressed by light. In lower vertebrates, the pineal gland is photosensitive, and is the site of a self-sustaining circadian clock. In mammals, including humans, the gland has lost direct photosensitivity, but responds to light via a multisynaptic pathway that includes a subset of retinal ganglion cells containing the newly discovered photopigment, melanopsin. The mammalian pineal also shows circadian oscillations, but these damp out within a few days in the absence of input from the primary circadian pacemaker in the suprachiasmatic nuclei (SCN). The duration of the nocturnal melatonin secretory episode increases with nighttime duration, thereby providing an internal calendar that regulates seasonal cycles in reproduction and other functions in photoperiodic species. Although humans are not considered photoperiodic, the occurrence of seasonal affective disorder (SAD) and its successful treatment with light suggest that they have retained some photoperiodic responsiveness. In humans, exogenous melatonin has a soporific effect, but only when administered during the day or early evening, when endogenous levels are low. Some types of primary insomnia have been attributed to diminished melatonin production, particularly in the elderly, but evidence of a causal link is still inconclusive. Melatonin administration also has mild hypothermic and hypotensive effects. A role for the pineal in human reproduction was initially hypothesized on the basis of clinical observations on the effects of pineal tumors on sexual development. More recent data showing an association between endogenous melatonin levels and the onset of puberty, as well as observations of elevated melatonin levels in both men and women with hypogonadism and/or infertility are consistent with such a hypothesis, but a regulatory role of melatonin has yet to be established conclusively. A rapidly expanding literature attests to the involvement of melatonin in immune function, with high levels promoting and low levels suppressing a number of immune system parameters. The detection of melatonin receptors in various lymphoid organs and in lymphocytes suggests multiple mechanisms of action. Melatonin has been shown to be a powerful antioxidant, and has oncostatic properties as well, both direct and indirect, the latter mediated by its effects on reproductive hormones. Finally, there are reports of abnormal daily melatonin profiles in a number of psychiatric and neurological disorders, but the significance of such abnormalities is far from clear.
机译：松果体的描述可以追溯到上古，但其在人类中的功能仍知之甚少。在白天和夜间的脊椎动物中，其主要产物荷尔蒙褪黑激素都是在昼夜周期的黑暗部分以有节奏的方式合成和释放的。褪黑激素的产生受内源性昼夜节律定时系统控制，并且也被光抑制。在低等脊椎动物中，松果体是光敏的，并且是自我维持的生物钟的位置。在包括人类在内的哺乳动物中，腺体失去了直接的光敏性，但通过多突触途径对光作出反应，该途径包括含有新发现的光色素黑色素的视网膜神经节细胞的一部分。哺乳动物的松果体还显示出昼夜节律振荡，但是在缺乏视交叉上核（SCN）的初级昼夜节律起搏器输入的情况下，这些振荡在几天之内就消失了。夜间褪黑激素分泌发作的持续时间会随着夜间持续时间的增加而增加，从而提供一个内部日历来调节光周期物种的繁殖季节和其他功能。尽管不认为人类是光周期性的，但季节性情感障碍（SAD）的发生及其成功的光疗表明，他们保留了一些光周期反应性。在人类中，外源性褪黑素具有促渗透作用，但仅在白天或傍晚内源性水平较低时才使用。某些类型的原发性失眠归因于褪黑激素的产生减少，尤其是在老年人中，但因果关系的证据仍无定论。褪黑激素的给药也具有轻度的降温和降压作用。松果体在人类生殖中的作用最初是根据对松果体肿瘤对性发育的影响的临床观察来推测的。最近的数据显示内源性褪黑激素水平与青春期发作之间的相关性，以及在性腺功能减退和/或不育症的男性和女性中褪黑激素水平升高的观察均与这种假说相符，但是褪黑激素的调节作用尚无定论。最终确定。迅速增长的文献证明褪黑激素参与免疫功能，高水平促进和低水平抑制许多免疫系统参数。在各种淋巴器官和淋巴细胞中褪黑激素受体的检测表明多种作用机制。褪黑素已被证明是一种强大的抗氧化剂，并具有直接和间接的抑癌特性，后者通过其对生殖激素的影响而介导。最后，有报道称许多精神病和神经病患者的每日褪黑激素谱异常，但是这种异常的重要性还远远不清楚。

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