Nocturnal Light and Nocturnal Rodents: Similar Regulation of Disparate Functions?
Nocturnal Light and Nocturnal Rodents: Similar Regulation of Disparate Functions?
复制标题
DOI：
10.1177/0748730413481921
复制
发表时间：
2013-04-01
影响因子：
3.5
通讯作者：
Morin, Lawrence P.
中科院分区：
文献类型：
--
作者：
Morin, Lawrence P.
研究者通常一次研究昼夜视觉系统的一个功能，无论是光接收、光信息向视交叉上核（SCN）的传递、节律相的光控制、运动活动或基因表达。这种集中的方法有很好的理由，但有时从更广泛的角度来看是有利的，询问所有的部分和功能如何完成整体。在这里，几个看似不同的昼夜视觉系统的功能进行了检查。它们在光调节方面具有共同的特征，并且在已知的程度上具有共同的输入神经解剖学。提出的观点是，有最多数据的3种下丘脑介导的光效应，昼夜节律时钟相移，抑制夜间运动（“负掩蔽”）和抑制夜间松果体功能，是由终止于SCN的共同光输入通路调节的。对于每一个，光触发一个相对固定的间隔响应，这是依赖于辐照度的，有效的刺激可以是非常短暂的光暴露，并且在没有额外光的情况下，响应继续完成。触发的固定长度响应间隔的存在对于理解调节昼夜节律相移的电路和机制特别重要，因为它意味着SCN时钟对光的响应不是瞬时的。这也可以解释为什么某些刺激（神经肽Y或新颖的车轮运行）在光照射后许多分钟给予能够阻止光引起的相移。对消极掩蔽的理解是复杂的，因为它可以被表示为一种积极的变化，即光诱导的睡眠，而不仅仅是运动的减少。急性夜间光照也会诱发肾上腺激素分泌和体温迅速下降，这些生理反应似乎与其他光照效应受到类似的调节。这几种反应的共同调控基础的可能性表明，更多的光诱导反应将会出现，并提出了关于光、SCN细胞解剖、SCN神经元的分子时钟机制以及调节不同下游活动的SCN吞吐量机制之间关系的问题。
Investigators typically study one function of the circadian visual system at a time, be it photoreception, transmission of photic information to the suprachiasmatic nucleus (SCN), light control of rhythm phase, locomotor activity, or gene expression. There are good reasons for such a focused approach, but sometimes it is advantageous to look at the broader picture, asking how all the parts and functions complete the whole. Here, several seemingly disparate functions of the circadian visual system are examined. They share common characteristics with respect to regulation by light and, to the extent known, share a common input neuroanatomy. The argument presented is that the 3 hypothalamically mediated effects of light for which there are the most data, circadian clock phase shifts, suppression of nocturnal locomotion ("negative masking"), and suppression of nocturnal pineal function, are regulated by a common photic input pathway terminating in the SCN. For each, light triggers a relatively fixed interval response that is irradiance-dependent, the effective stimulus can be very brief light exposure, and the response continues to completion in the absence of additional light. The presence of a triggered, fixed-length response interval is of particular importance to the understanding of the circuitry and mechanisms regulating circadian rhythm phase shifts because it implies that the SCN clock response to light is not instantaneous. It also may explain why certain stimuli (neuropeptide Y or novel wheel running) administered many minutes after light exposure are able to block light-induced phase shifts. The understanding of negative masking is complicated by the fact that it can be represented as a positive change, that is, light-induced sleep, not just as a reduction in locomotion. Acute nocturnal light exposure also induces adrenal hormone secretion and a rapid drop in body temperature, physiological responses that appear to be regulated similarly to the other light effects. The likelihood of a common regulatory basis for the several responses suggests that additional light-induced responses will be forthcoming and raises questions about the relationships between light, SCN cellular anatomy, the molecular clockworks of SCN neurons, and SCN throughput mechanisms for regulating disparate downstream activities.