A cholinergic antagonist, mecamylamine, blocks light-induced fos immunoreactivity in specific regions of the hamster suprachiasmatic nucleus.
A cholinergic antagonist, mecamylamine, blocks light-induced fos immunoreactivity in specific regions of the hamster suprachiasmatic nucleus.
复制标题
胆碱能拮抗剂美加明可阻断仓鼠视交叉上核特定区域中光诱导的 fos 免疫反应性。
DOI：
10.1016/0006-8993(93)91120-h
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发表时间：
1993
期刊：
影响因子：
2.9
通讯作者：
Turek,FW
中科院分区：
文献类型：
--
作者：
Zhang,Y;Zee,PC;Kirby,JD;Takahashi,JS;Turek,FW
最近的研究表明，光诱导的运动活动昼夜节律的相移与视交叉上核（SCN）中c-fos的表达有关。为了进一步探讨c-fos表达对光相移效应的重要性，我们检测了甲胺对SCN中光诱导的fos样免疫反应性（Fos-lir）的影响。选择甲胺是因为它是一种胆碱能拮抗剂，可以阻断光对金仓鼠昼夜活动节奏的相移效应。金仓鼠至少接受14天的光照和10小时的暗光照。然后将动物置于持续黑暗（DD）中，并在暴露于DD期间进行以下一种或多种处理：(1)单独使用车辆；(2)在昼夜节律时间（CT） 19时单独给药（450 μg, i.c.v）；(3)车辆在CT 19处加一个光脉冲；(4)在CT 19光脉冲前10分钟使用甲胺。与给药动物相比，甲胺阻断了光对运动活动昼夜节律的相移效应（P < 0.001）。CT 19的光脉冲在1小时内诱导SCN中的Fos-lir，而用载药或甲美胺处理对SCN中的Fos-lir没有明显影响。甲美胺预处理可使SCN中光诱导的Fos-lir显著降低75%。最引人注目的观察结果是甲美胺在SCN的背内侧区域对Fos-lir有明显的抑制作用，而在SCN的腹侧部分对Fos-lir几乎没有抑制作用。这些结果与光诱导活动节律的相移是由SCN中Fos的表达介导的假设一致，并表明SCN背内侧区域Fos的表达可能在生物钟的光诱导相移中起作用。
Recent studies have shown that light-induced phase shifts of the circadian rhythm of locomotor activity are associated with c-fosexpression in the suprachiasmatic nucleus (SCN) of rodents. In order to explore further the importance of c-fosexpression for the phase-shifting effects of light, we examined the effects of mecamylamine on light-induced Fos-like immunoreactivity (Fos-lir) in the SCN. Mecamylamine was chosen because it is a cholinergic antagonist that blocks the phase-shifting effects of light on the circadian activity rhythm in the golden hamster. Golden hamsters were entrained for at least 14 days to a 14 h light: 10 h dark photoperiod. Animals were then placed in constant darkness (DD) and during exposure to DD were subjected to one or more of the following treatments: (1) vehicle alone; (2) mecamylamine alone (450 μg, i.c.v.) at circadian time (CT) 19; (3) vehicle plus a light pulse at CT 19; (4) mecamylamine 10 min prior to the light pulse at CT 19. Mecamylamine blocked the phase-shifting effects of light on the circadian rhythm of locomotor activity when compared to vehicle-treated animals (P < 0.001). A light pulse at CT 19 induced Fos-lir in the SCN within 1 h, whereas treatment with vehicle or mecamylamine had no noticeable effect on Fos-lir in the SCN. Mecamylamine pretreatment dramatically reduced light-induced Fos-lir in the SCN by 75%. The most striking observation was the clear inhibition of Fos-lir by mecamylamine in the dorsomedial region of the SCN while there was little inhibition of Fos-lir in the most ventral portions of the SCN. These results are consistent with the hypothesis that light-induced phase advances in the activity rhythm are mediated by Fos expression in the SCN, and indicate that Fos expression in the dorsomedial region of the SCN may play a role in light-induced phase shifts in the circadian clock.