Effects of l-tetrahydropalmatine on conditioned place preference and expression of dopamine in the striatum of morphine dependent rats / 中华行为医学与脑科学杂志

ABSTRACT

Objective To observe effects of conditioned place preference (CPP) of morphine dependent rats,variation of dopamine neurotransmitter and its receptor 2 of the striatum in rats suffered from 1-tetrabydropalmatine(l-THP).Methods The CPP model was established by morphine injection in rats with a increasing dose for 10 days,with the initial dose of 10 mg · kg-1 and the final dose of 100 mg · kg-1,10 mg · kg-1 was increased each day,thus 100 nmg · kg-1 Was injected by day 10.Treatments with administration of 1-THP(3.76,1.88 and 0.94 mg/kg) were performed respectively for 6 days,and the effects of CPP for psychological dependence in these rats were observed.Striatum samples were taken out and their variable contents of dopamine neurotransmitter and its receptor 2 in striatum were detected by high performance liquid chromatography and immunohistochemisty,respectively.Results Compared with the NS treatment group,the time of animals treated with 1-THP (3.76 and 1.88 mg/kg) staying in drug-paired compartment were reduced (354 ± 58,373 ± 79) (P＜ 0.01) ;the raised of variation contents of dopamine neurotransmitter were reduced in striatum from those rats(5.49 ± 1.95,6.11 ± 1.05),while the expression level of dopamine receptor 2 was increased(0.08 ± 0.02,0.07 ± 0.03) (P ＜ 0.01 or P ＜0.05).Conclusion Reversing dopamine neurotransmitter and its receptor 2 in striatum of morphine dependent rats may be one of the possible mechanisms that 1-THP effectively inhibit the effects of morphine CPP.