Gagliano Humberto, Nadal Roser, Armario Antonio
Institut de Neurociències, Universitat Autònoma de Barcelona, Spain; Animal Physiology Unit (Faculty of Biosciences), Universitat Autònoma de Barcelona, Spain.
Institut de Neurociències, Universitat Autònoma de Barcelona, Spain; Psychobiology Unit (Faculty of Psychology), Universitat Autònoma de Barcelona, Spain.
Horm Behav. 2014 Nov;66(5):793-801. doi: 10.1016/j.yhbeh.2014.11.002. Epub 2014 Nov 14.
In male rats, a single exposure to a severe stressor such as immobilization (IMO) results in marked activation of the HPA axis and reduction of body weight gain. In addition, the HPA response to the same (homotypic) stressor is reduced, whereas the response to a different (heterotypic) stressor is enhanced for days. Although sex differences in the responsiveness of the HPA axis have been described, there are few studies about the influence of sex on long-lasting effects of stress. Thus, we have compared the consequences of a single exposure to IMO in male and female rats. Females showed a similar ACTH response to the first IMO associated with higher corticosterone, but they were more resistant than males to stress-induced loss of body weight. Unstressed females showed higher resting levels of ACTH and corticosterone, but they did not show the increase in the resting levels of HPA hormones observed in males on the day after IMO. During exposure to a different stressor (open-field) two days after IMO, enhanced corticosterone response and hypoactivity was observed in males, but not in females. Finally, a second exposure to IMO 8 days after the first one resulted in a reduction of the HPA response and of the negative impact on body weight as compared to the first exposure, and this protective effect was greater in females. In sum, IMO-exposed females showed a greater reduction of the response to a second IMO and appear to be more resistant than males to some of the negative impacts of IMO.
在雄性大鼠中，单次暴露于诸如束缚（IMO）等严重应激源会导致下丘脑 - 垂体 - 肾上腺（HPA）轴显著激活以及体重增加减少。此外，HPA 对相同（同型）应激源的反应会降低，而对不同（异型）应激源的反应会在数天内增强。尽管已经描述了 HPA 轴反应性的性别差异，但关于性别对应激长期影响的研究却很少。因此，我们比较了雄性和雌性大鼠单次暴露于 IMO 的后果。雌性对首次 IMO 的促肾上腺皮质激素（ACTH）反应与较高的皮质酮水平相似，但它们比雄性更能抵抗应激诱导的体重减轻。未受应激的雌性显示出较高的静息 ACTH 和皮质酮水平，但它们没有表现出雄性在 IMO 后一天观察到的 HPA 激素静息水平的增加。在 IMO 后两天暴露于不同应激源（旷场试验）时，雄性观察到皮质酮反应增强和活动减少，而雌性则未出现。最后，在第一次暴露于 IMO 8 天后再次暴露于 IMO，与第一次暴露相比，HPA 反应和对体重的负面影响有所降低，并且这种保护作用在雌性中更大。总之,暴露于 IMO 的雌性对第二次 IMO 的反应降低幅度更大，并且似乎比雄性更能抵抗 IMO 的一些负面影响。
