Rybkin I I, Zhou Y, Volaufova J, Smagin G N, Ryan D H, Harris R B
Neuroscience Department, Pennington Biomedical Research Center, Louisiana State University, Baton Rouge 70808, USA.
Am J Physiol. 1997 Nov;273(5):R1612-22. doi: 10.1152/ajpregu.1997.273.5.R1612.
Three experiments were conducted to investigate the effect of restraint stress applied at different times of the light-dark cycle on feeding behavior and body weight of rats. Sprague-Dawley rats were restrained for 3 h in restraining tubes either at the start or the end of the light cycle. There was a significant reduction in food intake on the day of restraint and no change in food intake during a 10-day recovery period in either experiment. Reductions of food intake on the day of restraint were about the same for both restrained groups compared with their controls. When stress was applied in the evening, eating was inhibited during the first 2 h after restraint, whereas in rats restrained in the morning, feeding was suppressed twice: during the 4 h after restraint and during the first 2 h of the dark cycle. Restraint induced a significant weight loss that was greater in the rats stressed in the morning. Neuropeptide Y (NPY) levels determined at the time of food suppression for both experiments (beginning of the dark cycle) revealed an elevation of NPY in the paraventricular nucleus of rats stressed in the morning compared with other groups, but no difference in hypothalamic NPY mRNA expression. Expression of uncoupling protein mRNA in brown adipose tissue and leptin mRNA in epididymal fat, measured at the start of the dark period, was not altered by stress. There was an elevation of dopamine turnover in the hypothalami of rats restrained at the end of light cycle, but not those restrained in the morning. These results show that restraint stress has a greater effect on metabolism and energy balance when it is applied in the morning. Additional studies are needed to elucidate mechanisms involved in the suppression of food intake 9 h after restraint.
进行了三项实验，以研究在昼夜明暗周期的不同时间施加束缚应激对大鼠进食行为和体重的影响。将斯普拉格-道利大鼠在光周期开始或结束时置于束缚管中束缚3小时。在束缚当天，食物摄入量显著减少，并且在两个实验的10天恢复期内食物摄入量均无变化。与对照组相比，两个束缚组在束缚当天的食物摄入量减少程度大致相同。当在傍晚施加应激时，束缚后的前2小时进食受到抑制，而在早晨受到束缚的大鼠中，进食被抑制了两次：在束缚后的4小时内以及在黑暗周期的前2小时内。束缚导致显著的体重减轻，且早晨受到应激的大鼠体重减轻更明显。在两个实验中（黑暗周期开始时）食物抑制时测定的神经肽Y（NPY）水平显示，与其他组相比，早晨受到应激的大鼠室旁核中的NPY升高，但下丘脑NPY mRNA表达无差异。在黑暗期开始时测量的棕色脂肪组织中解偶联蛋白mRNA的表达和附睾脂肪中瘦素mRNA的表达不受应激影响。在光周期结束时受到束缚的大鼠下丘脑多巴胺周转率升高，但早晨受到束缚的大鼠下丘脑多巴胺周转率未升高。这些结果表明，早晨施加束缚应激对代谢和能量平衡的影响更大。需要进一步的研究来阐明束缚后9小时抑制食物摄入所涉及的机制。
