褪黑素对吗啡戒断大鼠脑内cAMP和cGMP含量的影响

EFFECTS OF MELATONIN ON cAMP AND cGMP CONTENTS IN SOME BRAIN REGIONS OF MORPHINE WITHDRAWAL RATS

目的 :观察褪黑素 (MT)对吗啡戒断大鼠不同脑区cAMP和cGMP含量的影响。方法 :以剂量递增法连续皮下注射吗啡建立吗啡依赖模型 ,采用放射免疫学方法测定脑内cAMP和cGMP的含量。结果 :(1)MT对大鼠吗啡戒断症状具有明显的抑制作用 ;(2 )与对照组比较 ,吗啡依赖大鼠的纹状体、间脑、中脑、脑桥和海马内cAMP含量显著增高 (P <0 0 5 ,P <0 0 1) ,cGMP含量显著下降 (P <0 0 5 ,P <0 0 1)。与吗啡依赖组比较 ,催促戒断大鼠海马和纹状体内cAMP的含量显著升高 (P <0 0 5 ) ,而cGMP含量显著下降 (P <0 0 5 ,P <0 0 1) ,其他部位则无明显变化 ;(3)褪黑素急性治疗可使吗啡戒断大鼠纹状体、间脑、中脑、脑桥和海马内cAMP含量明显下降 (P <0 0 5 ,P <0 0 1) ,cGMP含量明显增高 (P <0 0 5 ,P <0 0 1)。结论 :MT可显著抑制大鼠吗啡戒断反应 ,并与调节中枢cAMP和cGMP含量有关。

Objective: To investigate the eff ec ts of melatonin on cAMP and cGMP contents in different brain regions of morphine withdrawal rats. Methods: A physical morphine dependent mod el of rats was established by subcutaneous injection of morphine in gradually in creasing doses. The contents of cAMP and cGMP in some brain regions of morphine dependent and withdrawal rats were determined by radioimmunoassay. R esults:(1)The morphine withdrawal symptoms of the rats were reliev ed s ignificantly by ip melatonin;(2)Compared with the controls, the cAMP content s in rat striatum, diencephalons, midbrain, pons and hippocampus of morphine dependent rats were significantly higher(P<0.05 or P<0.01), while the contents of cGMP in those brain regions were significantly lower(P<0 .05 or P<0.01). Compared with morphine-dependent group, the cAMP conten ts in striatum and hippocampus of morphine withdrawal rats were significantly in creased(P<0.05) and the cGMP contents were significantly decreased (P <0.05 or P<0.01), but there were no significant changes in the cAMP an d cGMP content s in other regions;(3)The cAMP contents in rat striatum, diencephalons, mid brain, pons and hippocampus of the morphine withdrawal rats were significantly reduced by ip MT(P<0.05 or P<0.01), but the cGMP contents were sign ificantly increased (P<0.05 or P<0.01). Conclusion : Melatonin may significantly attenuate the morphine withdrawal symptoms by adjusting the contents of cAMP and cGMP in some brain regions.