Landry G J, Yamakawa G R S, Mistlberger R E
Department of Psychology, Simon Fraser University, 8888 University Drive, Burnaby, BC, Canada V5A 1S6.
Brain Res. 2007 Apr 13;1141:108-18. doi: 10.1016/j.brainres.2007.01.032. Epub 2007 Jan 18.
Rats can anticipate a fixed daily mealtime by entrainment of a circadian timekeeping mechanism anatomically separate from the light-entrainable circadian pacemaker located in the suprachiasmatic nucleus. Neural substrates of this food-entrainable circadian system have not yet been fully elucidated. A role for the thalamic paraventricular nucleus (PVT) is suggested by observations that scheduled feeding synchronizes daily rhythms of glucose utilization and immediate early gene and circadian clock gene expression in this area. One study has reported absence of food anticipatory circadian activity rhythms in rats with PVT ablations. To determine whether this effect extends to other behavioral measures of food anticipation, rats received large radiofrequency lesions aimed at the PVT and were maintained on a 3-h meal provided each day 6 h after lights-on. Rats with unambiguously complete PVT ablation exhibited increased total daily activity, a change in the waveform of the nocturnal activity rhythm, but no change in the amplitude, duration, latency to appearance or persistence during total food deprivation of food anticipatory activity measured by activity at or near a food bin accessible via a small window in the recording cage. These results indicate that, while the PVT may modulate light-entrainable rhythms, it is not a critical input, oscillator or output component of the circadian system by which rats behaviorally anticipate a daily mealtime.
大鼠能够通过一种昼夜节律计时机制的同步作用来预测固定的每日进餐时间，这种机制在解剖学上与位于视交叉上核的可被光照同步的昼夜节律起搏器是分开的。这种食物可同步的昼夜节律系统的神经基质尚未完全阐明。丘脑室旁核（PVT）的作用是由以下观察结果所提示的：定时喂食可使该区域的葡萄糖利用、即刻早期基因和昼夜节律时钟基因表达的每日节律同步。一项研究报告称，PVT切除的大鼠没有食物预期的昼夜活动节律。为了确定这种效应是否扩展到食物预期的其他行为指标，对大鼠进行了针对PVT的大面积射频损伤，并在每天开灯后6小时提供一次3小时的进餐。明确完全切除PVT的大鼠表现出每日总活动增加，夜间活动节律的波形发生变化，但在通过记录笼中的小窗口可进入的食物箱处或其附近的活动所测量的食物预期活动在完全食物剥夺期间的幅度、持续时间、出现潜伏期或持续性没有变化。这些结果表明，虽然PVT可能调节可被光照同步的节律，但它不是大鼠行为上预测每日进餐时间的昼夜节律系统的关键输入、振荡器或输出成分。
