Der-Avakian Andre, Rozeske Robert R, Bland Sondra T, Watkins Linda R, Maier Steven F
Department of Psychology and Center for Neuroscience, University of Colorado, UCB 345, Boulder, CO 80309-0345, USA.
Psychopharmacology (Berl). 2007 May;191(4):899-907. doi: 10.1007/s00213-006-0677-8. Epub 2007 Jan 9.
We have previously shown that exposure to a single session of inescapable (IS), but not escapable (ES), tailshock can sensitize the subsequent conditioned place preference and locomotor responses to opioids, but not other drug classes. However, prior work suggests that IS might sensitize nonopioid drug responding if the drug were to be preceded by a mild stressor.
In the following experiments, we examined the effects of IS and ES on the subsequent locomotor response to brief footshock and/or cocaine administration.
First, we measured the locomotor response to cocaine (0, 1, 5, 10 mg/kg, intraperitoneally) 48 h after a single session of IS in adult, male Sprague-Dawley rats. Then, this procedure was repeated with 10 mg/kg cocaine, except that half of the rats received two footshocks immediately before drug administration. Finally, we manipulated the escapability of the initial stressor, as rats received either ES or yoked IS 48 h prior to footshock and cocaine administration.
IS did not affect the subsequent locomotor response to cocaine, but did enhance this response when cocaine administration was immediately preceded by two footshocks. The footshocks alone were without effect. This sensitizing effect was dependent on the escapability of the initial stressor, as ES did not alter the locomotor response to footshock and cocaine administration.
These results indicate that acute exposure to IS, but not ES, can sensitize the locomotor response to cocaine 48 h later, but only when cocaine administration is immediately preceded by a brief stressor.
我们之前已经表明，单次暴露于不可逃避（IS）而非可逃避（ES）的尾部电击会使随后对阿片类药物的条件性位置偏好和运动反应敏感化，但对其他药物类别则无此作用。然而，先前的研究表明，如果在使用非阿片类药物之前施加轻度应激源，IS可能会使其反应敏感化。
在以下实验中，我们研究了IS和ES对随后对短暂足部电击和/或给予可卡因的运动反应的影响。
首先，我们在成年雄性Sprague-Dawley大鼠单次接受IS 48小时后，测量其对可卡因（0、1、5、10mg/kg，腹腔注射）的运动反应。然后，对10mg/kg可卡因重复此过程，但一半大鼠在给药前立即接受两次足部电击。最后，我们改变了初始应激源的可逃避性，因为大鼠在接受足部电击和可卡因给药前48小时接受了ES或束缚IS。
IS并未影响随后对可卡因的运动反应，但当在给予可卡因之前立即给予两次足部电击时，确实增强了这种反应。单独的足部电击没有效果。这种敏感化效应取决于初始应激源的可逃避性，因为ES并未改变对足部电击和可卡因给药的运动反应。
这些结果表明，急性暴露于IS而非ES可使48小时后对可卡因的运动反应敏感化，但仅当在给予可卡因之前立即施加短暂应激源时才会出现这种情况。
