Janik D, Mrosovsky N
Department of Zoology, University of Toronto, Ont., Canada.
Brain Res. 1994 Jul 18;651(1-2):174-82. doi: 10.1016/0006-8993(94)90695-5.
The aim of this work was to assess the effect of lesions of the intergeniculate leaflet on nonphotic phase shifts produced by confining hamsters to novel running wheels for 3 h in the middle of the subjective day. In intact hamsters this procedure produces large phase advances provided that the hamsters maintain high levels of wheel running during the confinement. Intergeniculate leaflet lesions blocked or reduced phase shifts after confinement to a novel wheel. However, for most animals these lesions also reduced both the amount of activity during the 3 h pulse in the novel wheel and the amount of daily wheel running in the home cage. To boost activity of lesioned hamsters to levels associated with large phase shifts, the animals were confined to novel wheels at low ambient temperature. The lesioned hamsters still failed to show large phase shifts. The benzodiazepine triazolam also failed to induce phase shifts in lesioned animals, but it induced less activity in lesioned animals as compared to sham-operated controls. The data support the hypothesis that the intergeniculate leaflet conveys information about nonphotic phase-shifting to the circadian pacemaker in the suprachiasmatic nucleus. They also raise the possibility that some effects of intergeniculate leaflet lesions previously interpreted as having a photic basis, might be due to the activity-lowering effect of the lesions.
本研究的目的是评估膝间小叶损伤对在主观日中午将仓鼠置于新的跑步轮中3小时所产生的非光性相位偏移的影响。在完整的仓鼠中，只要仓鼠在受限期间保持高水平的轮子转动，这个过程就会产生大幅的相位提前。膝间小叶损伤会阻止或减少置于新轮子后产生的相位偏移。然而，对于大多数动物来说，这些损伤也会减少在新轮子中3小时脉冲期间的活动量以及在笼舍中每日的轮子转动量。为了将损伤仓鼠的活动提升到与大幅相位偏移相关的水平，将动物置于低温环境下的新轮子中。损伤的仓鼠仍然未能表现出大幅的相位偏移。苯二氮卓类药物三唑仑也未能在损伤动物中诱导相位偏移，但与假手术对照组相比，它在损伤动物中诱导的活动较少。这些数据支持了这样一种假设，即膝间小叶将有关非光性相位偏移的信息传递给视交叉上核中的昼夜节律起搏器。它们还提出了一种可能性，即膝间小叶损伤以前被解释为具有光性基础的一些效应，可能是由于损伤的活动降低效应。
