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.
ABSTRACT
Objective To observe the level of dopamine and its receptor in striatum from conditioned place preference (CPP) of rats administrated of morphine.And explore the mechanism of opioid-psychic dependence involving the levels of neurotransmitter and receptor.Methods CPP model was validated in morphine-dependence rats for 10 days.Striatum samples were harvested from two separate groups involving the saline group and morphine treated group (n =10 per experiment).The DA contents in striatum were detected in rats with colorimetry.Immunohistochemistry was applied to detect the differential expression levels of dopamine receptor 2 (DRD2)in samples.Results Compared with the saline group,higher content of neurotransmitter dopamine was observed in the morphine dependent rats (7.63 ±0.98 vs 5.23 ± 1.01,P＜0.01),while the expression level of DRD2 was down regulated (0.06 ± 0.02 vs 0.08 ± 0.02,P ＜ 0.01).Conclusion The increased expression of neurotransmitter dopamine and the decreased of DRD2 may be contributed to morphine-induced psychological dependence in morphine dependent rats.