两种吗啡依赖大鼠模型脑内单胺神经递质水平的比较

目的通过对吗啡诱导的躯体依赖与精神依赖两种大鼠模型脑内单胺类递质水平的比较，探讨其在吗啡依赖形成中的作用。方法采用剂量递增法复制吗啡依赖大鼠模型，然后用纳洛酮催促，引起躯体戒断症状。连续给予吗啡（5mg／kg，ip）6d，引起大鼠产生显著的条件性位置偏爱效应。脑组织去甲肾上腺素（NE）、5-羟色胺（5-HT）和多巴胺（DA）含量采用荧光分光光度法测定。结果吗啡依赖大鼠催促戒断后脑内NE和5-HT水平明显升高，DA水平下降。吗啡在引起大鼠明显位置偏爱的同时，使大鼠脑内DA和5-HT水平显著升高，NE无明显改变。结论吗啡依赖的形成和戒断与脑内单胺神经递质有密切关系，吗啡依赖的躯体戒断症状与NE升高有关，而吗啡诱导的精神依赖则与脑内DA水平升高有关。

Comparison of Monoamine Neurotransmitters in Two Morphine-dependent Rat Models

Objective To investigate the changes of monoamine neurotransmitters of the brain in physical dependence and psychic dependence induced by morphine in rats. Methods A physical dependent rat model was established with morphine in a gradually increasing doses and the withdrawal syndrome was scored after naloxone precipitation. The conditioned place preference （CPP） in rats induced by morphine was used to investigate psychic dependence in rats. Contents of norepinephrine （NE）, dopamine （DA） and serotonin （5-HT） in hypothalamus of rats were assayed with a fluorescent method. Results （1） In naloxone-precipitated withdrawal test of morphine-dependent model rats, after morphine had been withdrawn, morphine-abstinent rats presented marked withdrawal symptoms and signs, their withdrawal scores were significantly increased, and the levels of NE and 5-HT in the rat brain were obviously enhanced, but the content of DA was reduced. （2） In CPP test, morphine caused a marked place preference in rats and the levels of DA and 5-HT in the rat brain were obviously enhanced, but the content of NE was reduced. Conclusion Morphine dependence development and withdrawal are closely connected with monoamine neurotransmitters in CNS. In the physical dependent model induced by morphine in rats, the rising of NE and 5-HT in the rat brain were significant, but in psychic dependent model induced by morphine in rats, the levels of DA in the rat brain were enhanced predominately.