在大鼠切口疼痛模型中鞘内新斯的明对脊髓NO/cGMP信号转导系统的影响

目的 了解大鼠切口疼痛模型中鞘内（IT）新斯的明（NEO）对脊髓一氧化合酶（NOS）活性、一氧化氮（NO）产量和环鸟苷酸（cGMP）含量的影响。方法 雄性64只，随机分为四组，每组16只：假手术组（组I0、术前30minIT0．9％氯化钠20μl组（组Ⅱ）、术后30minITNEO10μg组（组Ⅲ）和术前30minITNEO10μg组（组Ⅳ）。按Brennan法制成切口疼痛模型，以累积疼痛评分确定疼痛行为。在术后2h断头取腰段脊髓，以分光光度法测定NOS活性、NO产量；放射免疫法测定cGMP含量／结果 组Ⅲ和组Ⅳ大鼠的累积评分均明显低于组Ⅱ（P＜0．01）。组Ⅱ的脊髓NOS活性、NO产量和cGMP含量均较组Ⅰ明显升高（P＜0．01）。组Ⅳ的脊髓NOS活性、NO产量和cGMP含量均较组Ⅰ明显升高（P＜0．01）。组Ⅳ的脊髓NOS活性、NO产量和cGMP含量均较组Ⅱ明显降低（P＜0．05或0．01）。而两用药组上述指标比较以及用药组与组I比较均无明显差别（P＞0．05）。结论 在大鼠切口疼痛模型中，术前IT NEO的抗伤害作用可能与NO／cGMP信号转导系统有关。

Effects of intrathecal neostigmine on nitric oxide/cyclic guanosine 3', 5'-monophosphate (NO/cGMP) signaling pathway of the spinal cord in a rat model of incisional pain

Objective To investigate the effects of intrathecal neostigmine on nitric oxide synthase (NOS) activity, nitric oxide (NO) production and cyclic guanosine 3 ', 5 '- monophosphate (cGMP)content of the spinal cord in a rat model of incisional pain. Methods Male SD rats weighing 250-300g were anesthetized with intraperitoneal pentobarbital sodium 40 mg@kg-1 . Intrathecal(IT) catheter was implanted and the tip of the cathter reached the lumbar region, according to the method of Yaksh. Incision was made in the plantar aspect of the left hindpaw under 1.4% isoflurane anesthesia, according to the method of Brennan. 64 male SD rats were were divided randomly into four groups. Group Ⅰ received IT 0.9% NaCl 20 μl and 30 min later inhaled 1.4% isoflurane for 5 min but no incision was made. Group Ⅱ received IT 0.9% NaC1 20 μl 30 min before incision. Group Ⅲ received IT neostigmine 10μg(10μl) 30 min after incision. GroupⅣ received IT neostigmine 10μg(10μl) 30 min before incision. In group Ⅲ and Ⅳ 0.9 % NaC1 10 μl was flushed through IT catheter after IT neostigmine administration. A cumulative pain score was utilized to assess pain behavior. The animals were decapitated 2h after incision and the spinal cord was immediately removed and lumbar enlargement of the spinal cord was dissected on ice. NOS activity, NO production and cGMP content were measured by spectrophotometry and radioimmunoassy. Results Cumulative pain score in group Ⅲ and group Ⅳ was significantly lower than that in group Ⅱ (P<0.01 ).NOS activity, NO production as well as cGMP content of the spinal cord increased significantly in group Ⅱ as compared with those in group Ⅰ (P<0.01). NOS activity, NO production and cGMP content of the spinal cord in group Ⅳ were significantly lower than those in group Ⅱ (P<0.05 or P < 0.01 ). In group Ⅲ NOS activity, NO production and cGMP content of the spinal cord tended to be lower than those in group Ⅱ, although the differences were not statistically significant. Conclusions In a rat model of incisional pain antinociceptive effect of IT administration of neostigmine may be associated with the NO/cGMP signaling pathway of the spinal cord.