背根神经节血红素加氧酶1过表达缓解小鼠神经病理性疼痛

Overexpression of heme oxygenase 1 in dorsal root ganglion alleviates neuropathic pain in mice

摘要:

目的：探讨背根神经节(dorsal root ganglion, DRG)中血红素加氧酶1(heme oxygenase 1, HO-1)的表达分布及在神经病理性疼痛中的作用。方法：构建保留性坐骨神经损伤(spared nerve injury, SNI)诱导的神经病理性疼痛模型；行为学检测机械性触诱发痛；免疫荧光染色检测DRG中HO-1在神经元中表达和分布；免疫印迹检测DRG中HO-1表达。结果：免疫荧光染色显示DRG中HO-1阳性神经元在SNI后数量显著减少；DRG中HO-1阳性神经元主要是IB4阳性的小型神经元(< 300 μm2)；连续5d腹腔注射CoPP能增加神经病理性疼痛小鼠的缩爪阈值；鞘内注射过表达HO-1的腺病毒相关病毒(adenovirus associated virus,AAV)能特异性浸染DRG神经元,并上调HO-1表达；同时能有效提高神经病理性疼痛小鼠的缩爪阈值,此效应持续21d 以上。结论：DRG中HO-1主要表达在IB4阳性的小型神经元；过表达DRG神经元中HO-1能有效缓解SNI诱导的神经病理性疼痛。

Abstract:

Objective: To explore the expression and distribution of heme oxygenase 1 (HO-1) in the dorsal root ganglion (DRG), and the effects of HO-1 overexpression in the DRG on the neuropathic pain in mice. Methods: The neuropathic pain was induced by the spared nerve injury (SNI) in mice. The mechanical allodynia was examined by behavioral test. The expression and distribution of HO-1 in the DRG neurons was checked by immunofluorescence staining. Western blot was used to evaluate the HO-1 expression in the DRG. Results: Immunofluorescence staining showed the HO-1 positive neurons in the DRG were dramatically decreased after SNI. The double immunostaining and the cell-size distribution analysis showed that most of HO-1 positive neurons were the IB4+ nonpeptidergic small-diameter neurons (< 300 μm2) in the DRG. After consecutive intraperitoneal injection of CoPP for 5 days, the paw withdrawal threshold was increased in mice suffering from neuropathic pain. AAV-HO-1 specifically infected the DRG neurons via intrathecal injection, increased the HO-1expression in the DRG, and significantly increased the paw withdrawal threshold in the neuropathic pain mice. This increase of the paw withdrawal threshold by AAV-HO-1 was maintained for >21d. Conclusion: The HO-1 is mainly expressed in IB4 positive small-size neurons in the DRG. Overexpression of HO-1 in the DRG neurons can effectively alleviate the neuropathic pain induced by SNI.