Institut de Neurociències, Universitat Autònoma de Barcelona, 08193 Bellaterra , Barcelona , Spain .
Stress. 2013 Nov;16(6):698-705. doi: 10.3109/10253890.2013.824964. Epub 2013 Aug 19.
Comparison of exposure to certain predominantly emotional stressors reveals a qualitatively similar neuroendocrine response profile as well as a reduction of physiological responses after daily repeated exposure (adaptation). However, particular physical components of the stressor may interfere with adaptation. As defective adaptation to stress can enhance the probability to develop pathologies, we studied in adult male rats (n = 10/group) swimming behavior (struggling, immobility and mild swim) and physiological responses (ACTH, corticosterone and rectal temperature) to daily repeated exposure to forced swim (20 min, 13 d) at 25 or 36 °C (swim25 or swim36). Rats were repeatedly blood-sampled by tail-nick and hormones measured by radioimmunoassay. Some differences were observed between the two swim temperature groups after the first exposure to forced swim: (a) active behaviors were greater in swim25 than swim36 groups; (b) swim25 but not swim36 caused hypothermia; and (c) swim36 elicited the same ACTH response as swim25, but plasma corticosterone concentration was lower for swim36 at 30 min post-swim. After daily repeated exposure, adaptation in ACTH secretion was observed with swim36 already on day 4, whereas with swim25 adaptation was not observed until day 13 and was of lower magnitude. Nevertheless, after repeated exposure to swim25 a partial protection from hypothermia was observed and the two swim conditions resulted in progressive reduction of active behaviors. Thus, daily repeated swim at 25 °C impairs adaptation of the hypothalamic-pituitary-adrenal axis as compared to swim at 36 °C, supporting the hypothesis that certain physical components of predominantly emotional stressors can interfere with the process of adaptation.
将某些主要情绪应激源暴露进行比较后发现，其神经内分泌反应特征相似，且在每日重复暴露（适应）后，生理反应会减少。然而，应激源的某些特定物理成分可能会干扰适应。由于应激适应不良会增加发生病变的可能性，因此我们研究了成年雄性大鼠（每组 10 只）游泳行为（挣扎、不动和轻度游泳）和生理反应（ACTH、皮质酮和直肠温度）对每天重复 25 或 36°C 强迫游泳（20 分钟，13 天）的适应情况。通过尾夹对大鼠进行重复采血，并通过放射免疫法测量激素。在第一次强迫游泳后，两组游泳温度之间观察到一些差异：（a）25°C 游泳组的主动行为比 36°C 游泳组更活跃；（b）25°C 游泳会导致体温降低，但 36°C 游泳不会；（c）36°C 游泳引起的 ACTH 反应与 25°C 游泳相同，但 36°C 游泳后 30 分钟的皮质酮浓度较低。在每日重复暴露后，36°C 游泳在第 4 天就观察到了 ACTH 分泌的适应，而 25°C 游泳直到第 13 天才观察到适应，且适应程度较低。然而，在重复暴露于 25°C 游泳后，观察到了体温过低的部分保护，且两种游泳条件导致了主动行为的逐渐减少。因此，与 36°C 游泳相比，每天重复 25°C 游泳会损害下丘脑-垂体-肾上腺轴的适应，这支持了某些主要情绪应激源的特定物理成分可能会干扰适应过程的假说。
