诺米芬新对慢性吗啡处理后小鸡自发活动量的影响

目的 :探求吗啡对刚出生的小鸡自发活动量的影响以及行为敏感化的多巴胺神经机制。方法 :连续 7d每天给予小鸡ip不同剂量的吗啡 (5、10、2 0mg·kg- 1 ) ,观察其行为敏感化效应 ,撤药 3d后观察多巴胺转运体阻断剂诺米芬新 (0 5、1mg·kg- 1 )的干预效果。结果 :反复给药后 ,5mg·kg- 1 吗啡显著增加小鸡的自发活动量 (P <0 0 5 ,P <0 0 1) ,而且其自发活动量随给药次数的增多而不断增高 ;2 0mg·kg- 1 吗啡则明显降低小鸡的自发活动量 (P <0 0 5 )。诺米芬新呈剂量依赖性增加 5mg·kg- 1 组小鸡的自发性活动量 (P <0 0 5 )。结论 :反复小剂量吗啡处理能够导致鸟类行为敏感化效应 ,多巴胺可能在其中起重要作用。

EFFECTS OF NOMIFENSINE ON LOCOMOTOR SENSITIZATION IN CHICKS PRETREATED WITH MORPHINE

Objective:To investigate the locomotor stimulant effect of morphine on newly hatched chicks and the role of dopaminergic mechanisms in opioid-induced locomotor sensitization. Methods: Newly hatched male chicks were administrated morphine of various doses (5,10,20 mg·kg -1·d -1, ip) for 7 days and 3 days after cessation of treatment challenged with dopamine reuptake blocker nomifensine (0.5,1 mg·kg -1, ip). Results: Repeated administration of 5 mg·kg -1 morphine significantly elicited progressive locomotor activity relative to saline (P<0.001) while 20 mg·kg -1 induced a behavioral depression (P<0.05). The locomotor responses to the dopamine reuptake blocker nomifensine were also dose-dependently sensitized in chicks pre-exposed to 5 mg·kg -1morphine(P<0.05). Conclusion: Behavioral sensitization to effects of morphine may be highly conserved across species, which supports the possibility that the increased dopaminergic activity is involved in the development of behavioral sensitization to morphine.