Effect of different extinction methods on morphine-induced conditioned place preference in mouse / 国际药学研究杂志

ABSTRACT

Objective To compare the effect of extinction using different methods and the subsequent reinstatement of morphine-primed on morphine-induced conditioned place preference (CPP). Methods Mouse received morphine(10 mg/kg, sc) or saline (10 mg/kg, sc) injections alternately for 8 days to establish CPP. Different methods were used for extinction. Program 1, withdrawal group. Extinction sessions were conducted 21 days after the CPP test at 7 days interval; Program 2, extinction test group. Extinction sessions were carried out once a day from the second day after the CPP test; Program 3, extinction training group. Extinction sessions began one day after the CPP test. Mice were treated alternately two trials daily, in compartments where they received saline instead of morphine. A test for reinstatement was performed on the 2nd or 7th day after all groups completed extinction by 5 mg/kg morphine-primed. Results Morphine injections induce strong CPP. In withdrawal group, CPP extinguished on the 35th day and maintained for at least 28 days. Six trials extinction tests and 4 trials extinction training caused morphine induced CPP extinction. The three programs mentioned above were all primed by 5mg/kg morphine. Conclusion Morphine induced mouse CPP model can maintain at least 28 days, both extinction test and training can accelerate the extinction of CPP, and reinstatement by 5 mg/kg morphine.