目的　探讨吗啡长时作用下分化的人成神经瘤ＳＨＳＹ５Ｙ细胞中ｃＡＭＰ系统变化以及ＰＫＡ对转录因子ｃＦｏｓ的磷酸化调节。方法　采用蛋白竞争结合法、酶活性测定法及同位素掺入法分别观察ｃＡＭＰ、ＰＫＡ 及ｃＦｏｓ 的变化。结果　（１） １００μｍ ｏｌ／Ｌ吗啡作用２ ｍ ｉｎ～３６ ｈ 可使ＳＨＳＹ５Ｙ细胞ｃＡＭＰ水平呈双相变化：短时作用下ｃＡＭＰ水平降低，随着吗啡作用时间的延长，ｃＡＭＰ水平逐渐回升，至３６ ｈ 时明显高于对照，这时加入１００ μｍ ｏｌ／Ｌ纳洛酮可诱发ｃＡＭＰ水平的反弹性超高现象。表明吗啡作用３６ ｈ 可使分化的ＳＨＳＹ５Ｙ细胞产生类吗啡依赖样变化；（２） 吗啡长时作用下，胞质可溶相ＰＫＡ活性也呈双相变化，而膜相ＰＫＡ 活性未见明显变化；（３）吗啡作用３６ ｈ 时，细胞ｃＦｏｓ磷酸化水平显著降低，ＰＫＡ抑制剂可抑制此作用；（４）纳洛酮可抑制上述ＰＫＡ 活性及ｃＦｏｓ 磷酸化水平的改变。结论　ＳＨＳＹ５Ｙ 细胞ｃＡＭＰＰＫＡ 系统的上调可能与吗啡依赖的形成有关，而且在吗啡依赖样细胞中ＰＫＡ可能通过磷酸酶而使细胞ｃＦｏｓ 发生去磷酸化，从而激活某些基因的转录，这可能是吗啡依赖时细胞产生适应性变化的重要机 Objective To investigate the changes of cAMP system in human SH-SY5Y cells and the phosphorylation of c-Fos, a transcription factor of PKA, in human neuroblastoma under long-term morphine administration. Methods The changes of cAMP, PKA and cFos were observed by protein competition binding assay, enzyme activity assay and isotope incorporation method. Results (1) The cAMP level in SHSY5Y cells treated with 100 μmol / L morphine for 2 to 36 hours showed a biphasic change: the cAMP level decreased after a short time, and gradually increased with the prolongation of morphine time. To 36 h was significantly higher than the control, then add 100 μm ol / L naloxone can induce high cAMP level of the rebound phenomenon. Morphine-dependent morphine-dependent changes were observed in SHSY5Y cells after 36 h of morphine treatment. (2) PKA activity in cytoplasmsoluble phase also showed biphasic changes under long-term morphine treatment, but no significant changes in PKA activity (3) The morphological changes of c-Fos phosphorylation of cells were significantly decreased after 36 h of morphine treatment, and PKA inhibitor could inhibit this effect; (4) Naloxone inhibited the changes of PKA activity and c-Fos phosphorylation. Conclusion The up-regulation of cAMP-PKA in SH-SY5Y cells may be related to the formation of morphine dependence. In morphine-dependent cells, PKA may dephosphorylate c-Fos by phosphatase and activate the transcription of certain genes, This may be an important mechanism by which cells undergo adaptive changes during morphine dependence