背侧海马内给予雷公藤内酯醇(T10)对慢性痛大鼠痛行为和抑郁样行为及其内小胶质细胞激活的影响

Effects of the dorsal hippocampal injection of triptolide (T10) on pain,depression-like behavior and microglia activation of dorsal hippocampal in chronic pain rats

目的:探究背侧海马内置管给予雷公藤内酯醇(T10)对于神经病理性痛模型大鼠痛行为和抑郁样行为,以及海马内小胶质细胞激活的影响。方法:采用L5脊神经结扎(SNL)的方法制作慢性神经病理性痛模型。利用von Frey丝刺激法连续观察造模后大鼠的痛行为学变化;运用强迫游泳(FST)和新奇摄食抑制实验(NSF)观察造模后动物的抑郁样行为;分别采用免疫组织化学染色和Western Blot方法观察大鼠背侧海马内电离钙绑定衔接分子1(Iba-1)的表达情况。结果:(1)痛行为学检测结果显示:与正常对照组相比,造模1 d后SNL模型大鼠机械性痛阈明显降低(P <0. 001),且术后21 d维持在较低水平(P <0. 001);从术后第14 d起背侧海马内置管连续给予T10至第21 d,观察到T10能够明显提高上述模型大鼠手术侧后足的机械性痛阈(P <0. 01)。(2)抑郁样行为学检测结果显示:SNL模型大鼠于术后21 d出现明显抑郁样行为,与对照组相比,NSF的不动时间和FST的潜伏期均明显延长(P <0. 05,P <0. 001);背侧海马内给予T10后,动物的NSF和FST抑郁样行为均有明显缓解(FST P <0. 05; NSF P <0. 001)。(3)免疫组织化学染色结果显示:SNL模型大鼠双侧背侧海马内Iba-1的表达水平均明显高于正常对照组;给予T10后,其背侧海马内小胶质细胞的激活均被显著抑制。(4) Western Blot结果显示:造模后21 d双侧背侧海马内I-ba1的表达明显上调(P <0. 01),连续给予T10后可以显著下调其内Iba-1的表达水平(P <0. 05)。结论:背侧海马内置管连续给予T10能有效缓解由SNL诱导的慢性痛模型大鼠的痛行为和抑郁样行为,其机制可能与抑制背侧海马内小胶质细胞的激活,进而减轻海马内炎症反应密切相关。

Objective： To observe the effects of dorsal hippocampal injection of triptolide（ T10） on pain behavior,depression-like behavior and the microglia cells activation in dorsal hippocampal of chronic pain modal rats.Methods：Chronic neuropathic pain model was made by L5 spinal nerve ligation（ SNL） method.The von Frey filament was used to observe the change of pain behavior; the forced swim test（ FST） and the novelty suppressed feeding test（ NSF） were used to observe the depression-like behavior after surgery.Immunohistochemical staining was applied to analyze theexpression of ionized calcium binding adaptor molecule 1（ Iba-1） in dorsal hippocampus.Western Blot was applied to qualitatively analyze the level of Iba-1 in dorsal hippocampus.Results：（ 1） The results of von Frey filament showed that the hind paw withdrawal mechanical threshold in modal rats were significantly decreased after surgery（ P〈0.001） and was stable until 21 d（ P〈0.001）.From the 14 th day to 21 st day after the operation,T10 was continuously administered in the dorsal hippocampus and it was observed that T10 could significantly improve the mechanical pain threshold of the ipsilateral foot of the above model rats（ P〈0.01）.（ 2） The results of depression-like behavior test showed that the SNL model rats appeared significantly depression-like behavior on 21 days after surgery,and the immobile time of NSF and the latency time of FST were significantly longer than those in the control group（ P〈0.05,P〈0.001）.Both NSF and FST depressive behavior were significantly decreased after T10 treatment in the dorsal hippocampus（ FST P〈0.05; NSF P〈0.001）.（ 3） Immunohistochemical staining results showed that the expression level of Iba-1 in the dorsal hippocampus of SNL model rats was obviously higher those in the control group.After T10 injected into the dorsal hippocampus,the activation of microglia in the dorsal hippocampus was significantly inhibited.（ 4） Western Blot results showed that the expression of I-ba1 in the bilateral dorsal hippocampi was higher than control group（ P〈0.01） at 21 d after model establishment,and after continuous T10 administration,the expression level of iba-1 in the bilateral dorsal hippocampi could be significantly down-regulated（ P〈0.05）.Conclusion： Continuous injection of T10 in bilateral dorsal hippocampal can effectively relieve the pain behavior and depression behavior induced by SNL surgery in rats.The mechanism may be that T10 inhibited the activation of microglia and alleviate inflammation in dorsal hippocampus.