高压氧对神经病理性痛大鼠疼痛行为学及脊髓背角NOS 表达的影响

目的：观察高压氧对神经病理性痛大鼠疼痛行为学及脊髓背角 NOS 表达的影响。方法成年雄性 SD大鼠32只，随机分成4组，每组8只，包括：假手术组（S 组）、坐骨神经结扎组（CCI 组）、HBO 预处理组（pre－HBO 组）和 HBO 后处理组（post－HBO 组）。所有大鼠 CCI 术前1 d 测量机械痛阈值基线（MWT）。 CCI 术后第1、2、3、7、14、21和第28天观察疼痛反应行为，测量 MWT。 CCI 术后第28天，对脊髓背角中 nNOS、 eNOS 及 iNOS 阳性神经元进行计数。结果CCI 术前4组 MWT 值无明显差异（ P ＞0．05）。每个时间点，与 S 组比较，pre－HBO、post－HBO 和 CCI 组MWT 值明显降低（ P ＜0．05），且 CCI 组下降幅度最大。每个时间点，与 CCI 组比较，pre－HBO 组和 post－HBO 组 MWT值明显高于 CCI 组（ P ＜0．05）。与 S 组比较，CCI 后第28天 CCI 组、pre－HBO 组和 post－HBO 组大鼠脊髓 nNOS 和iNOS 阳性神经元数量明显增多（ P ＜0．05）。 CCI 组大鼠脊髓 nNOS 和 iNOS 阳性神经元数量明显高于 pre－HBO 组和post－HBO 组（ P ＜0．05）。4组大鼠脊髓 eNOS 阳性神经元数量未见明显差异（ P ＞0．05）。结论高压氧对神经痛的发生有预防和治疗作用，可能通过降低 NOS 的表达缓解疼痛。

Effects of hyperbaric oxygen on pain-related behaviours and expression levels of nitric oxide synthase in rats with neuropathic pain

Objective To investigate the effects of hyperbaric oxygen ( HBO) on pain-related behaviours and expression levels of nitric oxide synthase in rats with neuropathic pain.Methods Thirty-two male Sprague Dawley rats were randomly divided into four groups; sham operation group ( group S), sciatic nerve ligation group ( CCI group), HBO pretreatment group (pre-HBO group) and HBO post-treatment group (post-HBO group),with 8 rats in each group.The baseline mechanical withdrawal thresholds ( MWT) were measured one day before CCI for all the rats.The pain-related behaviours were observed on 1d,2d,3d,7d,14d,21d,28d after CCI,and MWT was also measured.Moreover the numbers of nNOS, eNOS and iNOS positive neurons in cornu dorsale medullae spinalis were calculated on 28d after CCI.Results There was no significant difference in MWT before CCI among the 4 groups ( P >0.05).The MWT in pre-HBO group, post-HBO group and CCI group in every time point was significantly lower than that in group S ( P <0.05),moreover,the decrease degree in CCI group was the most obvious ( P <0.05).The MWT in pre-HBO group and post-HBO group in every time point was significantly higher than that in CCI group ( P <0.05).As compared with those in group S,the numbers of nNOS and iNOS positive neurons in CCI group,pre-HBO group and post-HBO group on 28d after CCI were significantly increased ( P <0.05).The numbers of nNOS and iNOS positive neurons in CCI group were significantly higher than those in pre-HBO group and post-HBO group ( P <0.05).However there were no significant differences in numbers of eNOS positive neurons among 4 groups ( P >0.05).Conclusion HBO has preventive and therapeutic effects on neuropathic pain,which can relieve pain, and its action mechanism may be correlated to the decrease of the expresion levels of NOS.