Encoding time of day and time of year by the avian circadian system
Encoding time of day and time of year by the avian circadian system
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DOI：
10.1046/j.1365-2826.2003.01003.x
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发表时间：
2003-04-01
影响因子：
3.2
通讯作者：
Brandstätter, R
中科院分区：
文献类型：
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作者：
Brandstätter, R
鸟类生理和行为的季节性节律性最重要的时代因素是光周期的年度周期。与哺乳动物相比，鸟类的调节机制知之甚少，因为光信息可以被视网膜和松果体以及大脑中的光感受器感知，光周期时间的测量可以参考至少三个自主的昼夜节律系统，即视网膜、松果体和下丘脑振荡器。在许多鸟类中，松果体褪黑激素的节律在昼夜节律组织中起着核心作用。血液中褪黑激素升高的持续时间反映了动物在自然光周期条件下以及在实验室不同的明/暗时间表下的夜间长度。在家雀中，一年中的时间是在特定的褪黑素信号中编码的，在长光周期中持续时间短而幅度大，在短光周期中持续时间长而幅度低，与光诱因是自然的还是人为的或强度的变化无关。当鸟类或分离的松果腺转移到恒定的条件下时，褪黑激素信号的特定特征在体内和体外都会保留下来。为了调节日常和季节性的行为和生理变化，褪黑素可能作用于不同的靶点，包括复杂的下丘脑振荡器，与哺乳动物不同，它并不局限于家雀的单个细胞组。越来越多的证据表明，鸣禽昼夜节律起搏系统的两个或多个组成部分之间的相互作用对于编码和存储关于时间的生物意义信息是必不可少的，从而为鸟类的光周期时间测量和后效作用提供基础。
The most important zeitgeber for seasonal rhythmicity of physiology and behaviour in birds is the annual cycle of photoperiod. Regulatory mechanisms are less well understood in birds than in mammals since photic information can be perceived by photoreceptors in the retina and the pineal gland, as well as in the brain, and photoperiodic time measurement might be performed with reference to at least three autonomous circadian systems, the retina, the pineal gland and a hypothalamic oscillator. In many bird species, the pineal melatonin rhythm plays a central role in circadian organization. Durations of elevated melatonin in the blood reflect night length when animals are kept under natural photoperiodic conditions, as well as under different light/dark schedules in the laboratory. In the house sparrow, time of year is encoded in a particular melatonin signal, being short in duration and high in amplitude in long photoperiods and being long in duration and low in amplitude in short photoperiods, independent of whether the light zeitgeber is natural or artificial or varies in strength. Specific features of the melatonin signal are retained in vivo as well as in vitro when birds or isolated pineal glands are transferred to constant conditions. To regulate daily and seasonal changes of behaviour and physiology, melatonin may act at various target sites, including a complex hypothalamic oscillator that, unlike that in mammals, is not confined to a single cell group in the house sparrow. There is increasing evidence that interactions between two or more components of the songbird circadian pacemaking system are essential to encode and store biologically meaningful information about time, and thus provide the basis for photoperiodic time measurements and after effects in birds.