De Boer S F, Slangen J L, Van der Gugten J
Department of Psychopharmacology, University of Utrecht, The Netherlands.
Physiol Behav. 1990 Jun;47(6):1089-98. doi: 10.1016/0031-9384(90)90357-a.
Plasma noradrenaline (NA), adrenaline (A) and corticosterone (CS) concentrations were determined in rats before, during and after 15-min exposure to a constantly electrified (2 mA) or nonelectrified prod which was mounted on the wall of the home cage either with or without bedding material on the floor. Concomitantly, exploration of the prod, freezing and prod-burying behavior were recorded. Both in the presence and absence of bedding material, rats explored the nonelectrified prod and showed a small increase in plasma NA and CS contents. Exploration of the prod was strongly reduced when the prod was electrified. In the presence of bedding material, shocked rats typically displayed burying behavior (active avoidance), whereas in the absence of bedding (i.e., burying option eliminated) shocked rats engaged in freezing behavior (passive avoidance). The passive avoidance situation was accompanied by larger A and CS increases but a lower NA rise as compared to the hormonal responses associated with the active avoidance situation. Administration of the anxiolytic chlordiazepoxide (CDP; 9 mg/kg intragastrically) attenuated the shock-induced suppression of prod exploration, decreased prod-burying behavior but, paradoxically, increased freezing behavior. Irrespective of bedding condition, the prod shock-induced elevations in plasma CS and A contents were completely abolished in CDP-treated rats. The rise in plasma NA was attenuated only in CDP-treated rats tested on a bedding-floor. The results indicate that passive (e.g., freezing) and active (e.g., burying) behavioral coping are each accompanied by specific and dissociated patterns of neurosympathetic, adrenomedullary and adrenocortical outflow. CDP-treatment shifts an animal's behavioral coping style from an active to a passive form of avoidance responding, but abolishes the accompanying adrenocortical and adrenomedullary activation.
测定了大鼠在暴露于持续通电（2毫安）或不通电的刺激物之前、期间和之后15分钟时血浆去甲肾上腺素（NA）、肾上腺素（A）和皮质酮（CS）的浓度。该刺激物安装在饲养笼壁上，饲养笼底部有无垫料。同时，记录对刺激物的探索、僵住和掩埋刺激物的行为。无论有无垫料，大鼠都会探索不通电的刺激物，血浆NA和CS含量略有增加。当刺激物通电时，对其的探索显著减少。在有垫料的情况下，受电击的大鼠通常表现出掩埋行为（主动回避），而在没有垫料（即消除掩埋选择）的情况下，受电击的大鼠表现出僵住行为（被动回避）。与主动回避情况相关的激素反应相比，被动回避情况伴随着更大的A和CS增加，但NA升高较低。给予抗焦虑药物氯氮卓（CDP；9毫克/千克灌胃）可减轻电击诱导的对刺激物探索的抑制，减少掩埋刺激物的行为，但矛盾的是，增加了僵住行为。无论垫料情况如何，CDP处理的大鼠中，刺激物电击诱导的血浆CS和A含量升高完全消除。仅在有垫料的饲养笼中测试的CDP处理的大鼠中，血浆NA的升高有所减弱。结果表明，被动（如僵住）和主动（如掩埋）行为应对方式分别伴随着神经交感、肾上腺髓质和肾上腺皮质流出的特定且不同的模式。CDP处理将动物的行为应对方式从主动回避转变为被动回避形式，但消除了伴随的肾上腺皮质和肾上腺髓质激活。
