Sumová A, Trávnícková Z, Peters R, Schwartz W J, Illnerová H
Institute of Physiology, Academy of Sciences of the Czech Republic, Prague.
Proc Natl Acad Sci U S A. 1995 Aug 15;92(17):7754-8. doi: 10.1073/pnas.92.17.7754.
Seasonal changes of daylength (photoperiod) affect the expression of hormonal and behavioral circadian rhythms in a variety of organisms. In mammals, such effects might reflect photoperiodic changes in the circadian pace-making system [located in the suprachiasmatic nucleus (SCN) of the hypothalamus] that governs these rhythms, but to date no functionally relevant, intrinsic property of the SCN has been shown to be photoperiod dependent. We have analyzed the temporal regulation of light-induced c-fos gene expression in the SCN of rats maintained in long or short photoperiods. Both in situ hybridization and immunohistochemical assays show that the endogenous circadian rhythm of light responsiveness in the SCN is altered by photoperiod, with the duration of the photosensitive subjective night under the short photoperiod 5-6 h longer than under the long photoperiod. Our results provide evidence that a functional property of the SCN is altered by photoperiod and suggest that the nucleus is involved in photoperiodic time measurement.
白昼时长（光周期）的季节性变化会影响多种生物体中激素和行为昼夜节律的表达。在哺乳动物中，此类影响可能反映了控制这些节律的昼夜节律起搏系统（位于下丘脑视交叉上核，即SCN）中的光周期变化，但迄今为止，尚未发现SCN的任何与功能相关的内在特性是依赖光周期的。我们分析了处于长光周期或短光周期的大鼠SCN中光诱导的c-fos基因表达的时间调控。原位杂交和免疫组织化学分析均表明，SCN中光反应性的内源性昼夜节律会因光周期而改变，短光周期下光敏主观夜的时长比长光周期下长5 - 6小时。我们的结果提供了证据，表明SCN的一种功能特性会因光周期而改变，并表明该核参与了光周期时间测量。
