鞘内注射Fyn-PSD-95拮抗剂对脊神经结扎大鼠的作用

Effects of intrathecal injection of Fyn-PSD-95 inhibitor in neuropathic pain in rat model of L5spinal nerve ligation

目的：观察鞘内注射Fyn—PSD-95拮抗剂Tat—FynP对L5脊神经结扎（SNL）大鼠痛觉过敏行为的影响，并探讨其作用机制。方法：60只SD大鼠随机分为5组（n=12）：空白组（N）、假手术组（S）、SNL组（C）、mTat—FynP给药组（M）、Tat—FvnP给药组（T）。N组不做任何处理，S组只暴露L5脊神经，C、M、T组大鼠行SNL术。C、M、T组于造模后第3～6天每天鞘内给予3％DMSO、mTat—FynP、Tat—FvnP。测定造模前后各组大鼠的机械刺激缩足反应阈值（MWT）及热刺激缩足潜伏期（TWL），Western blot检测脊髓腰膨大p-NR2B水平，免疫共沉淀检测Fyn与PSD-95的相互作用。结果：与C组比较，T组大鼠脊髓背角p-NR2B蛋白含量明显降低（P〈0．01），MWT及TWL明显增高（P〈0．01），Tat—FynP抑制Fyn与PSD-95的结合。结论：鞘内注射Tat—FynP可通过抑制Fyn与PSD-95的相互作用降低p-NR2B水平，从而缓解神经病理性痛大鼠的痛觉过敏。

Objective To explore the effects of intrathecal injection of Fyn-PSD-95 inhibitor Tat-FynP in hyperalgesia in rat model of L5 spinal nerve ligation and its underlying mechanism. Methods Sixty rats were randomly divided into five groups （n = 12 each）： naive group （group N）, sham operation （group S）, SNL group （group C）, mTat-FynP treatment group （group M）, Tat-FynP treatment group （group T）. Group N did not receive any operation in rats. In group S, the L5 spinal nerve was only exposed without ligation. In other three groups all received spinal nerve ligation （SNL）. Group N, group S and group C were administrated intrathecally with 3% DMSO within 3 to 6 days after SNL surgery. Other groups were treated with mTat-FynP （group M） and Tat-FynP （group T） at the same time points respectively. Behaviorally, mechanical withdrawal threshold （MWT） and thermal withdrawal latency （TWL） were measured in 3 days before and twenty first day after surgery separately. Western blot was used to detect the level of p-NR2B, while the effect of Tat-FynP on Fyn and PSD-95 was tested by co-immunoprecipitation. Results Compared with group C,p-NR2B was downregulated （P 〈 0.01 ） in group T, MWT was increased significantly and TWL was prolonged after Tat-FynP administration in group T（P 〈 0.01）. Tat-FynP can disrupt Fyn-PSD-95 protein-protein interaction. Conclusion Intratheeal injection of Tat-FynP can aim at reducing SCDH NR2B phosphorylation level by perturbing Fyn interactions with PSD-95 in neuropathic pain rats, thus attenuating pain hyperalgesia.