大鼠外周神经损伤后脊髓背角HMGB1表达上调参与机械性痛觉超敏

目的:研究HMGB1(high mobility group box-1)在神经病理性痛大鼠脊髓水平的表达变化,探索HMGB1在神经病理性痛发生发展中的作用,为治疗神经病理性痛提供新的理论依据和治疗靶点。方法:(1)雄性SD大鼠(180～220)g 12只,随机均分为三组:NS组:鞘内注射生理盐水;A组:鞘内注射HMGB1 1μg;B组:鞘内注射HMGB1 10μg。盲法用von Frey测定给药前及给药后1 h、1、3、7、14、21、28 d大鼠50%机械缩足阈值(me-chanical withdrawal threshold,MWT);(2)雄性SD大鼠(180～220)g 5只,免疫荧光双标观察HMGB1在脊髓背角的表达定位;(3)雄性SD大鼠(180～220)g 42只,随机均分为对照组(6只),SNL模型组(每时间点6只),West-ern Blot方法观察大鼠脊髓背角HMGB1对照及术后1、3、7、14、21、28 d的表达变化。结果:(1)大鼠脊髓鞘内注射HMGB1后诱发长时程机械性痛敏,A组在鞘内给药后7 d MWT明显下降(P<0.01),B组给药后1 h MWT即显著下降,且持续存在至少28 d;(2)免疫荧光双标显示:HMGB1主要表达于NeuN标记的神经元,而GFAP阳性的星形胶质细胞以及OX42阳性的小胶质细胞几乎不表达HMGB1;(3)Western Blot结果显示,脊髓背角HMGB1在SNL模型术后缓慢增高,7 d时增高最为显著,且持续至少28 d。结论:以上结果表明,外周神经损伤后脊髓水平HMGB1的表达上调可能在神经病理性痛的产生和维持中起着重要作用。

Nerve injury induced spinal HMGB1 upregulation was required for mechanical allodynia in rat

Objective: To examine the spinal expression of high mobility group box-1(HMGB1) in rat SNL model and its relationship with the development of neuropathic pain.Methods:(1) 12 male SD rats weighing 180~220 g were randomly divided into three groups: NS group,intrathecal injection of saline;Group A,intrathecal injection of 1 μg HMGB1;Group B,intrathecal injection of 10 μg HMGB1.50% mechanical withdrawal threshold(MWT) was measured using von Frey before and in 1 h,1 d,3 d,7 d,14 d,21 d and 28 d after intrathecal administration of HMGB1;(2) Double-labeling immunofluorescence histochemistry was used to investigate the cellular localization of HMGB1 positive components in the spinal dorsal horn;(3) 42 male SD rats weighing 180~220 g were randomly divided into control group and SNL model group,the expression of HMGB1 in rat spinal cord dorsal horn on 1 d,3 d,7 d,14 d,21 d and 28 d after the surgery were measured by Western Blot.Results:(1) Intrathecal injection of HMGB1 induced long-lasting mechanical allodynia.10 μg HMGB1 significantly decreased the MWT from 1 h after injection,and lasted for at least 28 d;(2) Double-labeling immunofluorescence histochemistry demonstrated that HMGB1was mainly expressed in neurons,but hardly to see in microglia and astrocytes;(3) Western Blot analysis indicated that the expression of HMGB1 was increased in the spinal dorsal horn after SNL,reached the peak at 7 d,and lasted at least for 28 d after SNL.Conclusion:These results suggested that peripheral nerve injury induces upregulation of HMGB1in the spinal dorsal horn.The upregulation of HMGB1 may play an important role in the development of mechanical allodynia after nerve injury.