Stress-induced changes in circadian rhythms of body temperature and activity in rats are not caused by pacemaker changes
Stress-induced changes in circadian rhythms of body temperature and activity in rats are not caused by pacemaker changes
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DOI：
10.1177/074873049701200109
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发表时间：
1997-02-01
影响因子：
3.5
通讯作者：
Daan, S
中科院分区：
文献类型：
--
作者：
Meerlo, P;vandenHoofdakker, RH;Daan, S
先前的研究表明，大鼠的社会压力（即被具有攻击性的雄性同种击败）会导致各种行为和生理变化，包括体温和活动的日常节律的改变。为了研究昼夜节律起搏器在这些压力引起的变化中的作用，进行了三个实验，依次研究起搏器周期、相位和对光的敏感性。在所有实验中，将大鼠置于优势同种的笼子中 1 小时，使其承受社会压力。这是连续两天在活动阶段的第二个小时到第五个小时之间进行的。实验动物受到居民的攻击并输掉了战斗，表现出顺从的行为。对照动物被放置在陌生但干净且空的笼子中1小时。实验1研究了社会压力对自由奔跑活动节律周期的影响。将大鼠单独饲养在持续昏暗的红光下。用红外探测器测量活性。社交失败导致多日活动减少，但自由奔跑的节奏期并未受到影响。在实验 2 中，作者研究了社会失败是否会引起急性相移。通过腹膜内植入发射器的无线电遥测技术测量体温和活动。社交互动结束后，实验动物被持续置于昏暗的红光下。社会压力导致体温和活动节律的幅度大幅降低，但没有发生明显的相移。在实验 3 中，作者研究了社交失败是否影响昼夜节律起搏器对光的敏感性，因为光引起的相移的大小被认为反映了起搏器的振幅。再次通过遥测技术测量体温和活动。两次社交失败后，将动物置于持续昏暗的红光下，第二次冲突后一天，在昼夜节律时间14时对动物进行单次l-h光脉冲（300勒克斯）。光脉冲引起体温节律的相位延迟，但应激组和对照组之间没有显着差异。数据表明，压力引起的活动和温度节律变化，以及早期实验中发现的行为和生理变化，并不是由昼夜节律起搏器的变化引起的。更一般地说，数据支持这样的观点，即明显的节律并不总是起搏器功能的可靠指示。
Previous work has shown that social stress in rats (i.e., defeat by an aggressive male conspecific) causes a variety of behavioral and physiological changes including alterations in the daily rhythms of body temperature and activity. To study the role of the circadian pacemaker in these stress-induced changes, three experiments were performed, successively addressing pacemaker period, phase, and sensitivity to Light. In all experiments, rats were subjected to social stress by placing them in the home cage of a dominant conspecific for 1 h. This was done on 2 consecutive days, between the second and fifth hours of the activity phase. Experimental animals were attacked by the resident and lost the fight as indicated by submissive behavior. Control animals were placed in an unfamiliar but clean and empty cage for 1 h. In Experiment 1, the effects of social stress on the period of the free-running activity rhythm were studied. Rats were individually housed under constant dim red light. Activity was measured with infrared detectors. Social defeat caused a reduction of activity for a number of days, but the period of the free-running rhythm was not affected. In Experiment 2, the authors studied whether social defeat induced acute phase shifts. Body temperature and activity were measured by means of radiotelemetry with intraperitoneally implanted transmitters. After the social interactions, experimental animals were kept under constant dim red light. Social stress caused a profound reduction in the amplitude of the body temperature and activity rhythm, but no significant phase shifts occurred. In Experiment 3, the authors studied whether social defeat affected the circadian pacemaker's sensitivity to light given that the size of light-induced phase shifts is thought to reflect pacemaker amplitude. Again, body temperature and activity were measured by means of telemetry. After double social defeat, animals were kept under continuous dim red Light, One day after the second conflict, animals were subjected to a single l-h light pulse (300 lux) at circadian time 14. The light pulse induced a phase delay of the body temperature rhythm, but there were no significant differences between the stress and control groups. The data indicate that stress-induced changes in activity and temperature rhythm, as well as behavioral and physiological changes found in earlier experiments, are not caused by changes in the circadian pacemaker. More generally, the data support the notion that overt rhythms are not always a reliable indication of pacemaker function.