关键词: 吗啡, 应激, 新颖寻求, 旷场

Abstract: To investigate the effect of repeated morphine-exposure on the behavior of stress response and novelty seeking, a method referring to open-field and playground maze was designed and used to investigate the behavior difference of repeated morphine-exposure rats and naive rats. Ten rats (morphine group) were injected ip with morphine (10 mg/kg), and the other ten rats (vehicle group) were injected saline solution. After treatment on consecutive 20 days, all rats were placed in the same playground maze for 15 min on each of 3 consecutive days, but a small novel object was put at the center of it the last day. On the first day, the locomotor response to novel playground maze could be recorded as response to the stressor. Then after adapted the maze environment twice, rats were attracted to the novel object in familiar environment, and the duration and number of approach the novelty could be recorded as graded response of novelty-seeking. It was detected that the morphine group rats exhibited lower initial locomotor response to novelty maze stress on the first test day. As there was a novel object at the center the third day, the two groups rats spent more time near the center and approach the center more frequently than the first two days, and the morphine group rats behaved more duration approach to the novelty than the vehicle group. These results indicated that morphine-exposure could alter traits of rats by decreasing the level of stress response and increasing the novelty seeking.

Key words: morphine, stress, novelty-seeking, open-field