Dielenberg R A, Arnold J C, McGregor I S
Department of Psychology, University of Sydney, NSW, Australia.
Pharmacol Biochem Behav. 1999 Feb;62(2):197-201. doi: 10.1016/s0091-3057(98)00064-1.
Previous studies have shown that predatory odors are a potent anxiogenic stimulus for rodents, yet the ability of benzodiazepines to block odor-induced anxiety remains uncertain. The present study reevaluated this issue using a novel apparatus that, in contrast to previous studies, allowed rats to hide from the odor in a small wooden "hide box" placed within a larger arena. The odor stimulus used was a fabric cat collar that had been worn by a domestic cat for a period of 3 weeks. The experiment was divided into three phases on successive days: 1) habituation, where all rats were placed in the apparatus without cat odor present; 2) conditioning, where rats were presented with the cat odor in the apparatus; and 3) test, where rats previously exposed to the odor were tested for a conditioned avoidance response in the absence of the odor. Results showed that rats exposed to the cat collar displayed a robust avoidance response, spending about 70% of a 20-min session in the hide box compared to 25% in control rats. This avoidance response was completely reversed in rats given a low dose (0.375 mg/kg) of midazolam. During the test phase, rats exposed to the cat odor on the previous day showed elevated levels of hiding when returned to the test apparatus without the cat odor present. This conditioned avoidance was significantly attenuated in rats who had received midazolam (0.375 mg/kg) during cat odor exposure but not in rats given the same dose during the test. These results show that low-dose midazolam is an effective anxiolytic agent in rats during exposure to predatory odor.
先前的研究表明，捕食者的气味对啮齿动物来说是一种强大的致焦虑刺激物，然而苯二氮䓬类药物阻断气味诱发焦虑的能力仍不确定。本研究使用了一种新颖的实验装置重新评估了这个问题，与先前的研究不同，该装置允许大鼠在放置于较大场地内的一个小木制“藏身箱”中躲避气味。所使用的气味刺激物是一个家猫佩戴了3周的织物猫项圈。实验在连续的几天内分为三个阶段：1）适应阶段，所有大鼠被放置在没有猫气味的实验装置中；2）条件反射阶段，大鼠在实验装置中接触猫气味；3）测试阶段，对先前接触过该气味的大鼠在没有气味的情况下进行条件性回避反应测试。结果显示，接触猫项圈的大鼠表现出强烈的回避反应，在20分钟的时间段内约70%的时间待在藏身箱中，而对照大鼠这一比例为25%。给予低剂量（0.375毫克/千克）咪达唑仑的大鼠，这种回避反应完全逆转。在测试阶段，前一天接触过猫气味的大鼠在回到没有猫气味的测试装置时，藏身时间增加。在接触猫气味期间接受过咪达唑仑（0.375毫克/千克）的大鼠中，这种条件性回避反应明显减弱，但在测试期间给予相同剂量的大鼠中则没有减弱。这些结果表明，低剂量咪达唑仑在大鼠接触捕食者气味期间是一种有效的抗焦虑药物。
