Dishman R K, Bunnell B N, Youngstedt S D, Yoo H S, Mougey E H, Meyerhoff J L
Department of Exercise Science, The University of Georgia, Athens 30602, USA.
Physiol Behav. 1998 Mar;63(5):911-7. doi: 10.1016/s0031-9384(98)00017-1.
We examined whether chronic circadian physical activity attenuates hypothalamic-pituitary-adrenal hormone responses after footshock with or without cage-switch stress. Young (45 g) male Fischer 344 rats were randomly assigned to individual suspended home cages (HC) or cages with activity wheels (AW) (12 h:12 h light-dark photoperiod). After 6 weeks, each animal from a pair matched on mass (HC and AW) and average weekly running distance (AW) was randomly assigned to controllable or uncontrollable footshock on 2 days separated by 24 h. Half the animals were returned to the HC after the first day of shock, and half were switched to a new shoebox cage. One animal of each pair could end the shock for both rats by performing an FR-2 lever press. The yoked animal could not control the shock. After shock on Day 2, trunk blood was collected after decapitation. Plasma adrenocorticotrophin (ACTH), corticosterone, and prolactin were determined by radioimmunoassay. ANOVA for a 2 Group (AW vs. sedentary) x 2 Test (controllable vs. uncontrollable shock) x 2 Condition (HC vs. cage-switch) design indicated a Group x Test x Condition effect [F(1, 48) = 5.07, p = 0.03] and a Test main effect [F(1, 47) = 6.93, p = 0.01] for ACTH. ACTH was higher for sedentary animals after uncontrollable footshock under cage-switch conditions and higher after uncontrollable versus controllable footshock when averaged across groups and cage conditions. No effects were found for corticosterone or prolactin. Our results extend to activity wheel running prior findings of a cross-stressor attenuation in plasma [ACTH] in response to cage-switch after treadmill exercise training, though the cross-stressor effect was additive with footshock. Consistent with our prior reports, the cross-stressor effect of wheel running was not apparent after footshock administered under home-cage conditions.
我们研究了长期的昼夜节律性身体活动是否会减弱在遭受足部电击（无论是否伴有更换笼子应激）后下丘脑-垂体-肾上腺激素的反应。将年轻（45克）雄性Fischer 344大鼠随机分配到单独悬挂的饲养笼（HC）或带有活动轮的笼子（AW）中（光照-黑暗周期为12小时：12小时）。6周后，从每对体重匹配（HC和AW）且平均每周跑步距离匹配（AW）的动物中，随机将每只动物在相隔24小时的两天接受可控或不可控的足部电击。电击第一天后，一半动物放回HC，另一半换到新的鞋盒笼。每对中的一只动物可以通过按压FR-2杠杆为两只大鼠终止电击。配对的另一只动物无法控制电击。在第2天电击后，断头采集躯干血。通过放射免疫测定法测定血浆促肾上腺皮质激素（ACTH）、皮质酮和催乳素。对2组（AW组与久坐组）×2测试（可控电击与不可控电击）×2条件（HC组与更换笼子组）设计进行方差分析，结果显示对于ACTH有组×测试×条件效应[F(1, 48) = 5.07, p = 0.03]以及测试主效应[F(1, 47) = 6.93, p = 0.01]。在更换笼子条件下不可控足部电击后，久坐动物的ACTH更高，并且在跨组和笼子条件平均后，不可控足部电击后的ACTH高于可控足部电击后的。对于皮质酮或催乳素未发现影响。我们的结果扩展到了活动轮跑步方面，先前的研究发现跑步机运动训练后，血浆[ACTH]对更换笼子的交叉应激衰减作用，尽管交叉应激效应与足部电击是相加的。与我们之前的报告一致，在饲养笼条件下给予足部电击后，活动轮跑步的交叉应激效应不明显。
