多巴胺D_1受体参与吗啡介导的小鸡条件性位置偏爱的表达

目的 :利用条件性位置偏爱模型探求吗啡对小鸡的奖赏作用及其相关的多巴胺机制。方法 :ip 2mg·kg-1吗啡对小鸡进行 4次条件化训练后进行条件性位置偏爱测试 ,测试前 15min分别ip生理盐水、0 .2 5mg·kg-1多巴胺D1受体拮抗剂SCH2 3390或者等剂量的多巴胺D2 受体拮抗剂雷氯必利 (raclopride) ,观察其干预效果。结果 :吗啡诱导出小鸡的条件性位置偏爱 (P <0 .0 1) ,条件性位置偏爱的表达被SCH2 3390阻断 (P <0 .0 5 ) ,而不受雷氯必利的影响 (P >0 0 5 )。结论 :吗啡的奖赏作用在鸟类中也有体现 ,小鸡可以成为研究药物成瘾的合适的模型。多巴胺D1受体可能参与对吗啡药物渴求的形成。

INVOLVEMENT OF DOPAMINE D1 RECEPTORS ON THE EXPRESSION OF MORPHINE-INDUCED PLACE PREFERENCE IN CHICKS

Objective: To investigate the rewarding effect of morphine on newly hatched chicks and the role of dopaminergic mechanisms on the expression of morphine-induced place preference. Methods: Newly hatched male chicks were administrated with morphine (2 mg·kg-1, intraperitoneally) for 4 conditioning trials, 0.25 mg·kg-1 dopamine D 1 receptor antagonist SCH23390 or the same dose of D 2 receptor antagonist raclopride intraperitoneally injected before the expression of place preference. Results: Morphine produced conditioned place preference(CPP) on chicks(P<0.01). The injection of SCH23390 (P<0.05) but not raclopride(P>0.05) abolished the expression of morphine-induced CPP. Conclusion: These results suggest that the rewarding effects of morphine may be highly conserved across species. Chicks might serve as an alternative animal model for investigating drugs of abuse. These data also indicate that D 1 receptor is critically involved in morphine-induced craving.