吗啡依赖及戒断大鼠脊髓和脑干中一氧化氮合酶基因的表达

The expression of nitric oxide synthase mRNA in spinal cord and brainstem during morphine dependence and withdrawal in rats

目的 观察吗啡依赖或吗啡戒断大鼠脊髓和脑干中一氧化氮合酶 (NOS)基因表达的变化。方法 以 β actin为内参照 ,用逆转录聚合酶链反应 (RT PCR)测定NOSmRNA的表达水平。结果 吗啡依赖大鼠脊髓和脑干NOS表达水平较正常对照大鼠降低 ,纳洛酮 ( 4mg·kg-1,ip)激发大鼠吗啡戒断症状 1h后脊髓和脑干中NOS表达水平明显升高 ,戒断 2h和 4h后NOS基因表达较 1h组减少。NOS抑制剂L N 硝基精氨酸甲酯 (L NAME ,10mg·kg-1)处理后大鼠吗啡戒断症状减少 ,同时脊髓和脑干的NOS基因表达水平较戒断 1h组明显降低。甲基东莨菪碱 ( 0 5mg·kg-1)处理组脊髓和脑干中NOS表达水平较戒断 1h组明显降低 ;选择性毒蕈碱受体M1拮抗剂 pirenzepine( 10mg·kg-1)处理组动物脊髓中NOS表达水平较戒断 1h组降低 ,而脑干中NOS表达水平没有改变 ;NMDA受体拮抗剂MK 80 1( 0 12 5mg·kg-1)处理后脊髓和脑干中NOS表达水平较戒断 1h组没有差异。结论 吗啡慢性处理后脊髓和脑干中NOSmR NA水平降低 。

AIM To study the expression of nitric oxide synthase (NOS) mRNA in spinal cord and brainstem during morphine dependence and withdrawal in rats. METHODS NOS mRNA levels were determined by using the reverse transcription polymerase chain reaction (RTPCR) method, the βactin mRNA expression was used as internal control. RESULTS The NOS mRNA levels in spinal cord and brainstem in morphine dependent rats which were made by chronic administration of morphine, were lower than those in normal control rats. The NOS mRNA levels were increased significantly in spinal cord and slightly in brainstem at 1 hour, declined gradually at 2 and 4 hours after the injection of naloxone (4 mg·kg -1 ,ip) in morphine dependent rats. In addition, either LNnitroarginine methylester (10 mg·kg -1 ), a competitive inhibitor of NOS, or scopolamine (05 mg·kg -1 ) was administered (ip) 30 min before the injection of naloxone in morphine dependent rats, the NOS mRNA levels in both spinal cord and brainstem were lower significantly than that of morphine withdrawal rats. Pretreatment with pirenzepine (10 mg·kg -1 ), an inhibitor of muscarinic receptor subtype 1, could only inhibit the expression of NOS mRNA induced by naloxone in spinal cord, but could not in brainstem. However, Pretreatment with the MK 801(0125 mg·kg -1 ), the expressions of NOS mRNA in both spinal cord and brainstem were not changed during morphine withdrawal. CONCLUSION The NOS mRNA levels in spinal cord were decreased by chronic treatment with morphine, and the expression of NOS mRNA during morphine withdrawal are reversed by inhibiting endogenous nitric oxide production or blocking muscarinic receptor.