摘要
目的 观察阿片激动剂长时程作用对NO cGMP信号转导系统的影响。方法 选用iNOScDNA稳定表达的NG LNCXiNOS细胞 ,采用NOS活性和cGMP放免测定 ,Western杂交和NADPH黄递酶组化染色技术。结果阿片类药物长时程作用剂量依赖性增高胞浆相iNOS活性和胞内cGMP含量 ,药物作用强弱顺序是DPDPE >DADLE >吗啡 ,EC50 都在nmol·L-1数量级。用纳洛酮急性戒断阿片耐受细胞 ,造成酶活性和cGMP水平增加更显著。DPDPE长时程作用还引起iNOS基因表达增强和NADPH黄递酶染色阳性细胞增多。结论 提示NO cGMP信号转导系统上调可能是阿片耐受和成瘾的重要生化改变。
AIM To determine the effect of chronic treatment with opioid agonists on NO-cGMP signal system on the basis of successful establishment of a NG-LNCXiNOS cell line expressing iNOS cDNA and a cell model of opioid tolerance and naloxone-precipitated withdrawal. METHODS NOS activity and cGMP content were determined by the conversion of 3H-Arginine to 3H-Citrulline and radioimmunoassay, respectively. Western blot analysis and NADPH diaphorase (NADPH-d) histochemical assay were used to detecte the level of iNOS gene expression and NADPH-d activity which is a histochemical marker for NOS. RESULTS Long-term exposure of NG-LNCXiNOS cells to various opioid agonists enhanced the cytosolic iNOS activity, accompanying the increase in intracellular cGMP content in a dose-dependent manner. The order of potencies was DPDPE>DADLE> morphine. The EC_ 50 values of the above indicators were nmol·L -1 level. When naloxone induced cell withdrawal, the iNOS activity and cGMP level were dramatically higher than those with agonists alone. Pretreatment of the cells with the more efficacious δ-ligand (DPDPE) for 48 hours also may lead to high-level expression of iNOS protein and elevate the number of NADPH diaphorase-positive cells. CONCLUSION Chronic opioid treatment was shown to up-regulate the NO-cGMP signal pathway, which may reflect an important biochemical change accounting for development of tolerance to and dependence on opiate. Thus, NG-LNCXiNOS cells provide a suitable system for studying the relationship between AC-cAMP and NO-cGMP signal system on the molecular mechanisms of opiate tolerance and dependence.
出处
《药学学报》
CAS
CSCD
北大核心
2000年第8期566-570,共5页
Acta Pharmaceutica Sinica
基金
国家自然科学基金!资助项目 (39670 82 7)
关键词
Δ-阿片受体
阿片类依赖
NO-CGMP
信号转导
opioid receptor
opiate dependence
nitric-oxide synthase
cyclic GMP
signal transduction
