目的　观察毒蕈碱 (M)受体拮抗剂对吗啡依赖大鼠脊髓和脑干前脑啡肽原 ( preproenkephalin ,PPE)和前强啡肽原 ( preprodynorphin ,PPD)mRNA表达的影响。 方法　本文利用逆转录聚合酶链反应 (RT PCR) ,以 β actinmRNA为内标检测了PPE和PPDmRNA。结果　吗啡依赖大鼠脊髓和脑干PPE基因表达和正常大鼠相比都略有增加 ,吗啡依赖大鼠注射纳洛酮激发戒断反应后 ,脊髓PPE基因表达增加 ,而脑干中变化不明显。吗啡依赖大鼠脊髓和脑干PPD基因表达都低于正常大鼠组 ,吗啡戒断反应时脊髓PPD基因表达在 1h变化不明显 ,2h时增加到峰值 ,4h时仍高于依赖组 ,而脑干强啡肽基因表达在 1h、2h和 4h时都明显减少。经M受体拮抗剂甲基东莨菪碱和M1拮抗剂 pirenzepine处理后大鼠脊髓和脑干PPE和PPD基因表达较戒断 1h组有不同程度的增加 ;经NMDA受体拮抗剂MK 80 1处理后 ,脊髓和脑干中PPE基因较戒断组 1h无明显差异 ,脊髓和脑干PPD基因表达较戒断组明显增加 ;而经NOS抑制剂L N 硝基精氨酸甲酯 (L NAME)处理后大鼠脊髓和脑干PPE基因表达较戒断 1h组有不同程度的增加 ,脊髓和脑干PPD基因表达变化不明显。脊髓和脑干中 β actin基因表达在各处理组之间没有差别。结论　M受体拮抗剂、NMDA受体拮抗剂和NOS抑制剂在吗啡戒断反应时增加 Objective To investigate the effect of muscarinic (M) receptor antagonist on the mRNA expression of preproenkephalin (PPE) and preprodynorphin (PPD) in spinal cord and brainstem of morphine dependent rats. Methods In this study, PPE and PPD mRNA were detected by reverse transcription-polymerase chain reaction (RT-PCR) and β actin mRNA as internal standard. Results The PPE gene expression in spinal cord and brainstem of morphine-dependent rats increased slightly compared with those in normal rats. After morphine-dependent injection of naloxone stimulated withdrawal response, the expression of PPE gene in spinal cord increased but the changes in brainstem did not change significantly . PPD gene expression in spinal cord and brainstem of morphine-dependent rats was lower than that in normal rats. PPD gene expression in spinal cord at morphine withdrawal reaction did not change significantly at 1h, peaked at 2h, and remained higher at 4h than those in dependent group The expression of dry dynorphin gene was significantly reduced at 1h, 2h and 4h. The expression of PPE and PPD in spinal cord and brainstem of rats treated with methyl-scopolamine and M1 antagonist pirenzepine increased to some extent compared with that of 1-hour withdrawal group. After NMDA receptor antagonist MK 80 1 treatment, PPE gene in the spinal cord and brainstem had no significant difference compared with that in the abstinence group for 1h, and the expression of PPD gene in spinal cord and brainstem increased obviously compared with that in the abstinence group. After treatment with NOS inhibitor L-NAME The PPE gene expression in the spinal cord and brainstem of rats increased to some extent compared with that in 1h group, and the expression of PPD gene in spinal cord and brainstem did not change obviously. The β actin gene expression in the spinal cord and brainstem did not differ between treatment groups. Conclusions M receptor antagonist, NMDA receptor antagonist and NOS inhibitor increase in response to morphine withdrawal