Cancela L M, Bregonzio C, Molina V A
Departamento de Farmacología, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Argentina.
Brain Res Bull. 1995;36(3):209-13. doi: 10.1016/0361-9230(94)00185-4.
The present study assesses the influence of different restraint schedules on behavioral parameters determined by a conflict test, namely the light-dark transitions (LDT) as well as the opiate modulation on the behavioral consequences induced by chronic restraint. Finally, another group of animals that received naloxone (NAL) and/or chronic stress was either exposed to a single foot shock session or administered a single dose of the beta-carboline FG 7142 (N'-methyl-beta-carboline-3-carboxamide) immediately prior to the LDT test. We observed that a single restraint session (2 h) induced a decrease of LDT and time spent in the lit box, while chronic restraint (2 h per day for up to 7 days) induced a significant increase in both parameters. However, this increasing effect was blocked by a NAL administration (2 mg/kg IP) prior to each of the seven restraint events. A single foot shock or FG administration produced a clear anxiogenic response, an effect that was absent in animals previously submitted to chronic stress. In addition, NAL pretreatment abolished the chronic stress-induced attenuating effect on the behavioral suppression induced after either foot shock or FG administration. Therefore, these findings demonstrate that a previous history of chronic stress, leading to adaptation, induced an anxiolytic-like effect, and attenuated the behavioral suppression produced by acute stressors. There seems to be an endogenous opiate mechanism involved in the behavioral influence induced by chronic stress.
本研究评估了不同约束方案对通过冲突试验确定的行为参数的影响，即明暗转换（LDT）以及阿片类药物对慢性约束诱导的行为后果的调节作用。最后，另一组接受纳洛酮（NAL）和/或慢性应激的动物，要么接受单次足部电击，要么在LDT试验前立即给予单剂量的β-咔啉FG 7142（N'-甲基-β-咔啉-3-甲酰胺）。我们观察到，单次约束（2小时）导致LDT和在亮箱中停留时间减少，而慢性约束（每天2小时，持续7天）导致这两个参数显著增加。然而，在七次约束事件中的每一次之前给予NAL（2mg/kg腹腔注射）可阻断这种增加效应。单次足部电击或FG给药产生明显的焦虑样反应，而在先前经历过慢性应激的动物中不存在这种效应。此外，NAL预处理消除了慢性应激对足部电击或FG给药后诱导的行为抑制的减弱作用。因此，这些发现表明，先前的慢性应激史导致适应，诱导了抗焦虑样效应，并减弱了急性应激源产生的行为抑制。慢性应激诱导的行为影响似乎涉及内源性阿片机制。
