EFFECT OF SEASON ON MELATONIN SECRETION IN SEASONAL AFFECTIVE DISORDER

许多类型的动物表现出深刻的行为变化和 一年中不同时间的生理学。在许多情况下，这些变化是 由日长的季节性变化(光周期)触发的。 松果体夜间分泌褪黑素的持续时间为 也受光周期持续时间的季节性变化的影响。在……里面 夏天，当夜晚很短的时候，夜间褪黑激素的持续时间 相应地，分泌物也很短。在冬天，它很长。在许多 动物夜间褪黑激素分泌持续时间的变化 光周期季节变化对水稻生长发育的影响 行为。大脑中控制季节性行为的部分对 褪黑素信号通过褪黑素受体检测其存在和 间隔计时机制，用于测量其存在的持续时间。 我们最近的研究(Z01 MH 02424-02 CPB)表明，人类在 在它们的进化过程中，有类似于 那些存在于动物体内，使它们能够检测到季节变化的东西 并改变夜间褪黑激素分泌的持续时间。 在实验中检测到了人类对光周期变化的反应 个人暴露在长短人工环境中的情况 ‘天’。在随后的实验(Z01 MH 02424-02CPB)中，我们研究了 生活在现代城市环境(地铁)中的健康人 华盛顿特区)，在那里他们经常暴露在人工 光，仍然能够检测到季节变化的持续时间 夜间，并通过修改 褪黑激素分泌的夜行期。我们发现它们的模式 夜间褪黑激素分泌对季节变化的反应 夜间持续时间，而男性则不是。这一发现表明 在对人造光的反应上可能存在性别差异 跟踪夜间长度的季节性变化的机制。 因为夜间褪黑激素持续时间的重要性 分泌物作为换能器的长度季节性变化的影响 关于动物行为的夜晚，重要的是要调查 褪黑素在季节性情感性精神障碍发病机制中的作用 精神障碍(SAD)伴反复出现的冬季抑郁。因此，在这方面， 项目，我们正在评估夜间活动的持续时间 在SAD患者中，褪黑激素的分泌有季节性的变化， 就像在健康女性身上一样。如果是这样的话，它可能会扮演一个 季节对这类患者情绪影响的化学传感器。 如果不是这样，那么它未能对季节做出反应可能是原因之一。 在某种程度上与这种疾病的发病机制有关。初步结果 从这个项目中可以看出褪黑素对 SAD患者的季节变化。

Many types of animals exhibit profound changes in their behavior and physiology at different times of year. In many cases, these changes are triggered by seasonal changes in the length of the day (photoperiod). The duration of nocturnal secretion of melatonin by the pineal gland is also modified by seasonal changes in duration of the photoperiod. In summer, when nights are short, the duration of nocturnal melatonin secretion is correspondingly short. In winter, it is long. In many animals, changes in the duration of nocturnal melatonin secretion chemically mediate the effects of seasonal changes in photoperiod on behavior. Parts of the brain that control seasonal behaviors respond to the melatonin signal via melatonin receptors that detect its presence and interval timing mechanisms that measure the duration of its presence. Our recent research (Z01 MH 02424-02 CPB) has shown that humans, in the course of their evolution, have conserved brain mechanisms similar to those that exist in animals that enable them to detect seasonal changes in daylength and modify the duration of nocturnal melatonin secretion. Human responses to change in photoperiod were detected in experimental conditions in which individuals were exposed to long and short artificial 'days'. In a subsequent experiment (Z01 MH 02424-02 CPB) we investigated whether healthy individuals living in a modern, urban environment (metro Washington, DC area), in which they are routinely exposed to artificial light, are still able to detect seasonal changes in the duration of the night and to respond to these changes by modifying the duration of the nocturnbal period of melatonin secretion. We found that patterns of nocturnal melatonin secretion responded to seasonal changes in the duration of the night, while those in men did not. This finding suggests that there may be gender differences in reponsiveness to artificial light of mechanisms that track seasonal changes in the length of the night. Because of the importance of the duration of nocturnal melatonin secretion as a tranducer of the effects of seasonal changes in the length of the night on animal behavior, it would be important to investigate whether melatonin plays a role in the pathogenesis of seasonal affective disorder (SAD) with recurrent winter depression. Accordingly, in this project, we are assessing whether or not the duration of nocturnal melatonin secretion varies on a seasonal basis in individuals with SAD, as it does in healthy women. If it does, then it might play a role as a chemical transducer of the effects of season on mood in such patients. If it does not, then its failure to respond to season might contribute in some way to the pathogenesis of the disorder. Preliminary results from this project suggest that melatonin is abnormally unresponsive to change of season in patients with SAD.