Kant G J, Bauman R A, Widholm J J, Ghosh S, Sharma N
Division of Neurosciences, Walter Reed Army Institute of Research, Washington, DC 20307-5100, USA.
Physiol Behav. 1997 Feb;61(2):279-84. doi: 10.1016/s0031-9384(96)00372-1.
The effects of sustained stress on response rate and temporal patterning (quarter-life) of rats performing either a previously learned fixed-interval schedule (FI 60) or learning an FI 60 simultaneously with stress onset were determined. Rats lived 24 h/day in operant cages, where they earned all of their food via lever-pressing. During the stress portion of each experiment, one group of rats was able to avoid or escape signalled intermittent footshock (Avoidance/ Escape Group), a second group (Yoked) did not have control over shock termination, a third group never received shock (Control). Shock trials were presented around the clock at approximately 5-min intervals and the stress portion of each study lasted 1-2 weeks. We have previously reported that rats tolerate this paradigm well and avoid/escape 99% of the shock trials. In rats previously trained on the FI task, both rate of responding and quarter-life values were significantly decreased on the first day of stress for both the Avoidance/Escape and Yoked Groups. Food intakes and quarter-life values were not significantly different from the controls by stress Days 3 and 2, respectively. In the acquisition study, controls learned the F1 task by Day 4 as judged by quarter-life of responding. FI task acquisition was significantly impaired in stressed rats compared to controls, not reaching asymptotic performance until Day 9 of stress. There were no major differences between the 2 stress groups in either study. These data demonstrate that stress may impair both the rate and patterning of behavior, and suggest that this rodent paradigm may usefully model some aspects of the effects of stress in humans.
研究了持续应激对执行先前习得的固定间隔时间表（FI 60）的大鼠或在应激开始时同时学习FI 60的大鼠的反应率和时间模式（四分位数寿命）的影响。大鼠每天24小时生活在操作箱中，通过按压杠杆获取所有食物。在每个实验的应激阶段，一组大鼠能够避免或逃脱有信号提示的间歇性足部电击（回避/逃脱组），第二组（配对组）无法控制电击终止，第三组从未接受电击（对照组）。电击试验全天大约每隔5分钟进行一次，每项研究的应激阶段持续1至2周。我们之前报道过，大鼠能很好地耐受这种模式，并且能避免/逃脱99%的电击试验。在先前接受FI任务训练的大鼠中，回避/逃脱组和配对组在应激的第一天，反应率和四分位数寿命值均显著降低。到应激第3天和第2天，食物摄入量和四分位数寿命值与对照组相比无显著差异。在习得研究中，根据反应的四分位数寿命判断，对照组在第4天学会了FI任务。与对照组相比，应激大鼠的FI任务习得明显受损，直到应激第9天才达到渐近表现。在两项研究中，两个应激组之间没有主要差异。这些数据表明，应激可能损害行为的速率和模式，并表明这种啮齿动物模式可能有效地模拟人类应激影响的某些方面。
