Droste Susanne K, Chandramohan Yalini, Hill Louise E, Linthorst Astrid C E, Reul Johannes M H M
Henry Wellcome Laboratories for Integrative Neuroscience and Endocrinology, Dorothy Hodgkin Building, University of Bristol, Bristol, UK.
Neuroendocrinology. 2007;86(1):26-37. doi: 10.1159/000104770. Epub 2007 Jun 25.
Evidence is accumulating that the regular performance of exercise is beneficial for stress coping. However, the hypothalamic-pituitary-adrenocortical (HPA) axis of voluntarily exercising rats has never been comprehensively investigated.
Therefore, male Sprague-Dawley rats were given access to a running wheel in their home cage for 4 weeks in which they ran 4-7 km per night.
After 4 weeks, the exercising animals showed significantly less body weight gain, less abdominal fat tissue, decreased thymus weight, and increased adrenal weight (relative to body weight). Furthermore, tyrosine hydroxylase (TH) mRNA levels were selectively increased in the right adrenal medulla indicating an increase in sympathoadrenomedullary capacity in exercising rats. No changes were observed in paraventricular corticotropin-releasing hormone (CRH), arginine-vasopressin (AVP) and oxytocin mRNA levels. Mineralocorticoid receptor (MR) mRNA levels in hippocampus and glucocorticoid receptor (GR) mRNA levels in frontal cortex, parvocellular paraventricular nucleus and anterior pituitary were unchanged, whereas GR mRNA levels were increased in distinct hippocampal cell layers. Early morning baseline levels of plasma ACTH and corticosterone were similar in both groups. Interestingly, the response to different stressful stimuli (e.g. forced swimming, novelty) revealed that the exercising rats showed stressor-specific changes in HPA hormone responses. Forced swimming evoked a markedly enhanced response in corticosterone levels in the exercising rats. In contrast, if rats were exposed to a novel environment, exercising rats showed a much lower response in corticosterone than the control animals. However, the response in ACTH to either stressor was comparable between groups. Thus, in exercising rats physically demanding stressors evoke enhanced glucocorticoid responses whereas mild psychologically stressful stimuli such as novelty result in an attenuated glucocorticoid response. Interestingly, this attenuated hormone response corresponded with the observation that the exercising rats showed less anxious behaviour in the novelty situation.
The differential responses in plasma corticosterone levels to different types of stress in the face of comparable responses in ACTH levels underscore the existence of critical regulatory control mechanisms at the level of the adrenal gland. We have hypothesized that changes in the sympathoadrenomedullary input may play an important role in these distinct glucocorticoid responses to stress. Our previous studies have shown similar changes in voluntarily exercising mice. Therefore, we conclude that the effects of exercise on the organism are not species-specific. Thus, our observations may have translational implications for the human situation.
越来越多的证据表明，经常进行锻炼有利于应对压力。然而，对于自愿运动的大鼠的下丘脑 - 垂体 - 肾上腺皮质（HPA）轴从未进行过全面研究。
因此，将雄性Sprague-Dawley大鼠置于其饲养笼中的跑轮上4周，它们每晚跑4 - 7公里。
4周后，运动的动物体重增加明显减少，腹部脂肪组织减少，胸腺重量减轻，肾上腺重量增加（相对于体重）。此外，酪氨酸羟化酶（TH）mRNA水平在右侧肾上腺髓质中选择性增加，表明运动大鼠的交感肾上腺髓质能力增强。室旁促肾上腺皮质激素释放激素（CRH）、精氨酸加压素（AVP）和催产素mRNA水平未观察到变化。海马中的盐皮质激素受体（MR）mRNA水平以及额叶皮质、小细胞室旁核和垂体前叶中的糖皮质激素受体（GR）mRNA水平未改变，而GR mRNA水平在海马不同细胞层中增加。两组的清晨血浆促肾上腺皮质激素（ACTH）和皮质酮基线水平相似。有趣的是，对不同应激刺激（如强迫游泳、新奇环境）的反应表明，运动大鼠在HPA激素反应中表现出应激源特异性变化。强迫游泳使运动大鼠的皮质酮水平反应明显增强。相反，如果大鼠暴露于新环境中，运动大鼠的皮质酮反应比对照动物低得多。然而，两组对任何一种应激源的ACTH反应相当。因此，在运动大鼠中，体力要求高的应激源会引起增强的糖皮质激素反应，而轻度心理应激刺激（如新奇环境）则导致糖皮质激素反应减弱。有趣的是，这种减弱的激素反应与运动大鼠在新奇环境中表现出较少焦虑行为的观察结果一致。
在ACTH水平相当的情况下，血浆皮质酮水平对不同类型应激的差异反应强调了肾上腺水平存在关键的调节控制机制。我们推测交感肾上腺髓质输入的变化可能在这些对压力的不同糖皮质激素反应中起重要作用。我们之前的研究表明，自愿运动的小鼠也有类似变化。因此，我们得出结论，运动对生物体的影响不是物种特异性的。因此，我们的观察结果可能对人类情况具有转化意义。
