Drugan Robert C, Eren Senem, Hazi Agnes, Silva Jennifer, Christianson John P, Kent Stephen
Department of Psychology, Conant Hall, University of New Hampshire, 10 Library Way, Durham, NH 03824-3567, USA.
Pharmacol Biochem Behav. 2005 Oct;82(2):397-403. doi: 10.1016/j.pbb.2005.09.011. Epub 2005 Oct 19.
The present study compared the effects of three different water temperatures (20, 25, and 30 degrees C) and stressor controllability on several physiological and behavioral endpoints in an intermittent swim stress paradigm. The escape latency of rats in the 20 and 25 degrees C water was less than that observed for the 30 degrees C group. Both escape and yoked groups at 20 and 25 degrees C exhibited moderate to severe hypothermia following the swim stress session that returned to prestress levels 30-40 min post-stress. At 30 degrees C core body temperature (Tb) only decreased by 1 degree C for either swim group. Following swim, serum corticosterone (CORT) levels were significantly elevated in both escape and yoked groups in comparison to confined and home cage controls. The confined control group showed a significant elevation that was approximately halfway between the home cage control and the swim stress groups. At 30 degrees C, there was still a significant elevation of serum CORT in both swim groups in comparison to confined and home cage controls. Therefore, 30 degrees C appears to be the optimal water temperature to evaluate stress controllability effects in the current paradigm. In a final experiment, swim stressor controllability effects were examined in a 5 min forced swim test (FST) 24 h following the initial stress exposure. Rats exposed to yoked-inescapable swim stress at 30 degrees C exhibited more immobility than their escapable swim stress and confined counterparts, while the escape and confined controls did not differ. These results demonstrate that the behavioral deficits observed in the FST are attributable to the stress of inescapable swim and not swim stress per se.
本研究在间歇性游泳应激范式中，比较了三种不同水温（20、25和30摄氏度）及应激源可控性对多个生理和行为终点的影响。20和25摄氏度水温组大鼠的逃避潜伏期短于30摄氏度组。20和25摄氏度水温下的逃避组和束缚组在游泳应激试验后均出现中度至重度体温过低，应激后30 - 40分钟恢复到应激前水平。在30摄氏度时，两个游泳组的核心体温（Tb）仅下降1摄氏度。游泳后，与禁闭组和笼养对照组相比，逃避组和束缚组的血清皮质酮（CORT）水平均显著升高。禁闭对照组的血清皮质酮水平显著升高，约为笼养对照组和游泳应激组的中间值。在30摄氏度时，与禁闭组和笼养对照组相比，两个游泳组的血清CORT水平仍显著升高。因此，在当前范式中，30摄氏度似乎是评估应激可控性影响的最佳水温。在最后一项实验中，在初次应激暴露24小时后的5分钟强迫游泳试验（FST）中检测游泳应激源可控性的影响。在30摄氏度下接受束缚性不可逃避游泳应激的大鼠比可逃避游泳应激组和禁闭组的大鼠表现出更多的不动行为，而逃避组和禁闭对照组之间没有差异。这些结果表明，在FST中观察到的行为缺陷归因于不可逃避游泳的应激，而非游泳应激本身。
