Ruarte M B, Alvarez E O
Unidad de Farmacología del Comportamiento (UNIFCO), Facultad de Ciencias Médicas, Universidad Nacional de Cuyo, Mendoza, Argentina.
Braz J Med Biol Res. 1999 Jan;32(1):99-106. doi: 10.1590/s0100-879x1999000100015.
When rats are exposed to unknown environments where novelty and fear-inducing characteristics are present (conflictive environments), some specific behaviors are induced and exploration is apparently modulated by fear. In our laboratory, a new type of plus-maze was designed as a model of conflictive exploration. The maze is composed of four arms with different geometrical characteristics, differing from each other by the presence or absence of walls. The degree of asymmetry was as follows: NW, no wall arm; SW, a single high wall present; HL, a low and a high wall present, and HH, two high walls present. The four arms were arranged at 90 degrees angles and the apparatus was called the elevated asymmetric plus-maze (APM). The purpose of the present study was to assess the behavioral profile of rats exposed for a single time to the APM with or without treatment with benzodiazepine. Increasing doses of diazepam were injected intraperitoneally in several groups of male, 90-day-old Holtzman rats. Distilled water was injected in control animals. Thirty minutes after treatment all rats were exposed singly to a 5-min test in the APM. Diazepam induced a biphasic modification of exploration in the NW and SW arms. The increase in the exploration score was evident at low doses of diazepam (0.25-1.0 mg/kg body weight) and the decrease in exploration was found with the higher doses of diazepam (2.0-3.0 mg/kg body weight). Non-exploratory behaviors (permanency) were not affected by benzodiazepine treatment. In the HL arm, exploration was not modified but permanency was increased in a dose-dependent manner. In the HH arm, exploration and permanency were not affected. Results are compatible with the idea that exploration-processing mechanisms in conflictive environments are modulated by fear-processing mechanisms of the brain.
当大鼠暴露于具有新奇性和诱发恐惧特征的未知环境（冲突环境）中时，会诱发一些特定行为，并且探索行为显然会受到恐惧的调节。在我们实验室，设计了一种新型的十字迷宫作为冲突性探索的模型。该迷宫由四个具有不同几何特征的臂组成，这些臂因有无墙壁而彼此不同。不对称程度如下：NW，无壁臂；SW，有一个高壁；HL，有一个低壁和一个高壁；HH，有两个高壁。四个臂以90度角排列，该装置被称为高架不对称十字迷宫（APM）。本研究的目的是评估单次暴露于APM且接受或未接受苯二氮䓬治疗的大鼠的行为特征。在几组90日龄雄性霍尔兹曼大鼠中腹腔注射递增剂量的地西泮。给对照动物注射蒸馏水。治疗30分钟后，所有大鼠单独在APM中进行5分钟的测试。地西泮在NW和SW臂中诱导了探索行为的双相改变。在低剂量地西泮（0.25 - 1.0 mg/kg体重）时，探索得分明显增加，而在高剂量地西泮（2.0 - 3.0 mg/kg体重）时，探索得分降低。非探索行为（停留时间）不受苯二氮䓬治疗的影响。在HL臂中，探索行为未改变，但停留时间以剂量依赖方式增加。在HH臂中，探索和停留时间均未受影响。结果与冲突环境中的探索处理机制受大脑恐惧处理机制调节的观点一致。
