Circadian System of Diurnal Rodents: Integrated Physiological/Behavioral Approach

日常生物计时，最好地反映在外行人对人类“时差”或轮班工作疾病的感知上，是通过神经起搏器（SCN）和环境同步剂的复合相互作用来调节的。起搏器在接近但不完全是 24 小时的恒定环境条件下，以自由运行的昼夜周期自主驱动依赖的生化、生理和行为功能，同时环境夹带或同步剂将起搏器的相位和频率校正为当地时间。许多哺乳动物昼夜节律研究，特别是生理方面的研究，仅限于实验室大鼠和金仓鼠。为了区分昼夜哺乳动物和更为人所知的夜间哺乳动物的昼夜节律“线路”之间的差异，该研究将研究三个昼夜物种在昼夜节律功能的连续阶段中选定的关键问题，包括来自娱乐环境的感觉输入、SCN节律发生器的生理特性和行为输出。 将在这三种昼间啮齿动物中进行生理和行为昼夜节律输出测量，以阐明日间活动哺乳动物的昼夜节律调节。选择羚羊地松鼠、十三纹地松鼠和东部花栗鼠作为模式物种，以最大限度地减少长期阻碍昼夜哺乳动物昼夜行为功能研究进展的操作问题，并评估生态差异广泛的沙漠、草原和森林物种的昼夜节律变化跨度。 问题将包括实验室和现场夹带的光采样过程、环境温度以及循环体温在昼夜节律功能中的作用，以及通过使用脑室内注射卡巴胆碱来描绘“光模仿”相位响应曲线系统（PRC）；关键SCN神经肽（NP-II、VIP、SS、NPY）的分布将通过免疫细胞化学方法加上计算机图像处理来确定，以定量测定共定位的免疫反应性。 最后，还将研究相对于其他大脑区域的 SCN 节律输出的体外和体内记录。这些数据可以作为一个有用的模型，用于更好地理解哺乳动物昼夜节律系统的功能，更广泛地用于设想 SCN 相对简单的神经元回路能够控制对比的夜间和昼夜节律行为模式的方法。

Daily biological timekeeping, best reflected in the perception of lay persons in terms of human "jet-lag" or shift-work maladies, is regulated by a composite interaction of neural pacemaker (SCN) and environmental synchronizing agents. The pacemaker autonomously drives dependent biochemical, physiological and behavioral functions with free-running circadian period under constant environmental conditions close to but not exactly 24-hours, while the environmental entraining or synchronizing agent corrects phase and frequency of the pacemaker to local time. Much mammalian circadian research, particularly the physiological aspect, has been limited to laboratory rats and golden hamsters. In an attempt to distinguish differences between the circadian "wiring" of diurnal mammals and better known nocturnal mammals, the study will examine selected key issues for three diurnal species in successive stages of circadian function including sensory input from the environment for entertainment, physiological properties of the SCN rhythm generator, and behavioral output. Physiological and behavioral circadian output measurements will be employed in these three diurnal rodents to clarify circadian regulation in day-active mammals. The antelope ground squirrel, 13- lined ground squirrel, and eastern chipmunk were chosen as model species to minimize operational problems that have long hindered progress of research on circadian behavioral function in diurnal mammals, and also to assess circadian variation span in ecologically widely divergent desert, prairie, and forest species. Issues will include the light-sampling process for entrainment in lab and field, the role of environmental temperature as well as cyclic body temperature in circadian function, and the delineation of a "light-mimicking" phase response curve system (PRC) by use of intraventricular injection of carbachol; the distribution of key SCN neuropepetides (NP-II, VIP, SS, NPY) will be determined by immunocytochemical methods plus computerized image processing for quantitative determination of co-localized immunoreactivity. Finally, in vitro and in vivo recording of SCN rhythmic output relative to other brain areas will also be investigated. The data may serve as a useful model for better understanding the functioning of diurnal circadian systems of mammals, and more generally for envisioning the means by which the relatively simple neuronal circuitry of the SCN is able to control contrasting nocturnal and diurnal circadian behavior modes.