Brief exposure to a mild stressor enhances morphine-conditioned place preference in male rats.
Brief exposure to a mild stressor enhances morphine-conditioned place preference in male rats.
复制标题
短暂暴露于轻度应激源会增强雄性大鼠的吗啡条件位置偏好。
DOI：
10.1007/s00213-004-1780-3
复制
发表时间：
2004
影响因子：
3.4
通讯作者：
Grau,JamesW
中科院分区：
文献类型：
--
作者：
Ferguson,AdamR;Patton,BrianneC;Bopp,AnneC;Meagher,MaryW;Grau,JamesW
RationaleExposure to moderate tail shock [3, 0.75 s, 1 mA, 20 s interstimulus interval (ISI)] can enhance pain reactivity (hyperalgesia) in rats. This hyperalgesia reflects an unconditioned response that transfers across contexts and is associated with enhanced Pavlovian fear conditioning to aversive unconditioned stimuli (US). It is possible that moderate shock also enhances learning about appetitive stimuli such as a reinforcing drug.ObjectivesThe present study examined the effect of moderate shock exposure on unconditioned psychomotor activation and appetitive conditioning using a morphine place-preference task.MethodsDuring training, rats were given moderate shock or restraint and then received subcutaneous morphine at one of four doses (0.0, 0.2, 1.0, or 5.0 mg/kg) and were transferred to a conditioning apparatus. Five hours later, animals were given discrimination training in a different context. Animals received 2 days of training, each separated by a day of testing for preference. To test the impact of shock on psychomotor activation, subjects were given shock or restraint and one of two doses of morphine (0.0 mg/kg or 5.0 mg/kg) and placed in a box to monitor activity.ResultsVehicle-treated shocked rats showed a conditioned place aversion. Subjects that received morphine showed a dose-dependent place preference that was facilitated by moderate shock exposure. Shock also enhanced the motor activation produced by morphine.ConclusionsThese results indicate that the affective state produced by moderate shock has a negative valence that is sufficient to support a conditioned place aversion. This state is associated with a general sensitization that enhances processing of appetitive US.
