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首页> 外文期刊>The European Journal of Neuroscience >Short-term exposure to constant light promotes strong circadian phase-resetting responses to nonphotic stimuli in Syrian hamsters.
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Short-term exposure to constant light promotes strong circadian phase-resetting responses to nonphotic stimuli in Syrian hamsters.

机译：短期暴露在恒定光照下可促进叙利亚仓鼠对非光刺激的强烈昼夜相变反应。

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Abstract Behavioral (nonphotic) stimuli can shift circadian rhythms by serotonin (5-HT) and/or neuropeptide Y (NPY) inputs to the suprachiasmatic nucleus (SCN) circadian clock. Based on the idea that behavioral phase resetting is modulated by endogenous changes in postsynaptic sensitivity to such transmitters, hamsters were exposed to constant light (LL; approximately 250 lx) for 1-3 days, which suppresses locomotor activity and eliminates the daily rhythm of SCN 5-HT release measured by microdialysis. Groups subjected to brief LL or maintained under a light/dark cycle (LD) received phase-resetting treatments with the 5-HT(1A,7) agonist (+/-)-2-dipropyl-amino-8-hydroxyl-1,2,3,4-tetrahydronapthalene (8-OH-DPAT) or sleep deprivation (SD). Animals were released to constant darkness at the start of the treatments. Phase advances to 8-OH-DPAT and SD during the day were 11 and 3 h for LL vs. 2 and 1 h for LD, respectively. Phase delays during the night were -12 and -5 h for LL vs. no responses for LD, respectively. Phase-transition curves for both LL treatments had slopes approximating 0, indicative of Type 0 phase resetting. For all treatments, the degree of locomotor suppression by LL was not correlated with the phase shift magnitude. Re-establishing locomotor activity by overnight food deprivation did not prevent potentiated shifting to SD. However, re-establishing peak extracellular 5-HT levels by intra-SCN 5-HT reverse microdialysis perfusion in LL did significantly reduce potentiated 8-OH-DPAT phase advances. Constant light also enhanced intra-SCN NPY-induced phase advances during the day (6 vs. 2 h for LD). These results suggest that LL promotes Type 0 phase resetting by supersensitizing 5-HT and/or NPY postsynaptic responses and possibly by attenuating the amplitude of the circadian pacemaker, thus enhancing circadian clock resetting nonspecifically.
机译：摘要行为（非光合）刺激可通过血清素（5-HT）和/或神经肽Y（NPY）输入到视交叉上神经节（SCN）昼夜节律来改变昼夜节律。基于这样一种想法，即行为相的重置是由突触后敏感性对这种发射物的内源性变化调节的，仓鼠被暴露在恒定的光线下（LL;大约250 lx）1-3天，这抑制了运动活动并消除了SCN的日常节律通过微透析测量5-HT释放。经历短暂LL或保持在明/暗周期（LD）下的组接受了5-HT（1A，7）激动剂（+/-）-2-二丙基-氨基-8-羟基-1的相重置处理， 2,3,4-四氢萘（8-OH-DPAT）或睡眠剥夺（SD）。在治疗开始时，动物被释放到恒定的黑暗中。白天，LL分别为11和3小时，而LD为2和1小时，相较于8-OH-DPAT和SD提前。 LL的夜间相位延迟分别为-12和-5 h，而LD则无响应。两种LL处理的相变曲线均具有接近0的斜率，表明类型0的相位复位。对于所有治疗，LL对运动的抑制程度与相移幅度均不相关。通过隔夜食物剥夺来恢复运动活动并不能阻止向SD的潜在转变。但是，通过LL内SCN 5-HT逆向微透析灌注重建峰值细胞外5-HT水平确实显着降低了增强的8-OH-DPAT相进展。持续不断的光照也增强了白天由SCN NPY诱导的阶段进展（LD分别为6小时和2小时）。这些结果表明，LL通过使5-HT和/或NPY突触后反应超敏并可能通过减弱昼夜节律起搏器的振幅来促进0型相位重置，从而非特异性地增强了昼夜节律重置。

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