硫化氢参与腰椎间盘突出症模型大鼠痛觉高敏

H2S expression in the hyperalgesia of rat lumbar disc herniation model

目的探讨腰椎间盘突出模型大鼠痛觉高敏与背根神经节（DRG）中内源性硫化氢（H2S）合成酶[胱硫醚-β-合成酶（CBS）及胱硫醚-β-裂解酶（CSE）]的表达之间的关系及其机制。方法将大鼠平均分为腰椎间盘突出症模型组（LDH）和假手术组（Sham），于术前1d、术后3、7、14、21、28、35d分别检测模型组和假手术组大鼠疼痛行为学表现，并分离提取相应时间点造模同侧L5-L6 DRG，检测CBS及CSE的蛋白表达变化。另外，在手术后第7天鞘内注射CBS抑制剂羧甲基羟胺半盐酸盐AOAA，检测给药后0．5、1．0、2．0、4．0、8．0、12．0、24．0h后对模型大鼠痛阈值的影响。结果大鼠造模同侧足底在术后3d即产生机械疼痛撤足反应[PWT：（8．30±1．28）g比（3．75±1．30）g，P=0．027]及双后肢负重差[WB：（7．14±1．11）g比（36．47±5．08）g，P=0．000），一直持续到术后28d[（12．50±0．71）g比（8．73±1．16）g，P=0．022；（5．32±3．42）g比（34．83±1．66）g，P=0．000]，与机械痛敏不同的是，热痛撤足反应仅在术后第7天下降明显[PWL，（13．76±1．32）s比（9．82±0．46）s，P：0．006]，然后逐渐恢复。同时，与假手术组比较，模型组大鼠的DRG中CBS蛋白表达在术后3～28d均显著上升（0．65±0．05比1．01±0．03，P=0．000），而CSE的表达没有变化（1．08±0．14比1．09±0．15，P=0．996）。鞘内注射CBS的抑制剂AOAA能显著逆转大鼠痛觉高敏。结论DRG中CBS的表达与腰椎间盘突出症疼痛密切相关。

Objective To investigate the relationship between hyperalgesia mechanism of lumbar disc herniation （LDH） models and the expression of endogenous hydrogen sulfide synthase in the rat dorsal root ganglion （DRG） and explore the pain mechanism. Methods Model rats were divided to LDH group and sham group, then tested for mechanical allodynia, thermal hyperalgesia, hindlimb body weight - bear- ing differences and rotarod testat 3 days before surgery and 3, 7, 14, 21, 28 and 35 days after surgery. Protein extracted from ipsilateral （ L5 - L6） DRGs of nucleus pulposus treated （ NP - treated） and sham rats were tested by Western blotting for the expression of cystathionine-β-synthase （CBS） and cystathi- onine -β-lyase （CSE） according to the time point of behavior test. In addition, intrathecal injection of CBS inhibitor AOAA within seventh days after surgery, the effects of 0.5, 1.0, 2.0, 4.0, 8.0, 12.0, 24.0 h after drug administration on the pain threshold of rats were detected. Results Mechanical allodyn- ia pawl withdraw threshol （PWT） and the body weight （WB） bearing difference in ipsilateral hindpaw de- veloped 3 day [ PWT： （8.30 ±1.28） g vs. （3.75 ± 1.30） g, P = 0. 027 ] after surgery and lasted until 28 days [WB： （7. 14±1.11） g vs. （36.47±5.08） g, P=0.000）. Unlike mechanical allodynia, the thermal withdrawal latency PWL only decreased significantly on the left side 7 days after surgery and gradu- ally recovered, comapred with sham group. At the same time, theexpression of CBS in postoperative 3 days to 28 days were significantly increased, whilethere was no change in the expression of CSE （ 1.08± 0. 14 vs. 1.09±0. 15, 7th days, P = 0. 996）. Intrathecal injection of CBS inhibitor AOAA significantly re- versed pain hyperalgesia in rats. Conclusion Our results suggest that expression of CBS in DRG contrib- utes to radiculopathy of lumbar disc herniation. Targeting CBS/HzS may represent a potential treatment for neuropathic pain caused by LDH.