脊髓小胶质细胞在小鼠慢性心力衰竭后慢性疼痛中的作用

Role of spinal cord microglia in chronic pain after chronic heart failure in mice

目的评价脊髓小胶质细胞在小鼠慢性心力衰竭(CHF)后慢性疼痛中的作用。方法选择SPF级健康雄性C57BL/6小鼠18只,8~12周龄,体质量20~25 g,采用随机数字表法分为3组(n=6):假手术组(Sham组)、CHF组和CHF+小胶质细胞抑制剂PLX3397组(CHF+PLX组)。采用结扎左冠状动脉前降支的方法法制备小鼠CHF模型。CHF+PLX组于造模前7 d至造模后28 d持续喂养含PLX3397的饲料。术后28 d时采用超声心动图评估小鼠心功能。分别于造模前1 d(T_(0))和造模后1、3、7、14、28 d(T_(1~5))时测定热缩足潜伏期(TWL)和机械缩足反应阈(MWT)。T_(5)时痛阈测定结束后,深麻醉下处死小鼠,取T_(2~6)和L_(4~6)脊髓组织,采用免疫荧光法检测脊髓背角小胶质细胞标志物Iba1的表达。结果与Sham组比较,CHF组小鼠左心室射血分数和左心室短轴缩短率降低,左心室舒张末期内径和左心室收缩末期内径升高,T_(4~5)时TWL缩短,MWT降低,脊髓背角Iba1表达上调(P<0.05);与CHF组比较,CHF+PLX组小鼠左心室射血分数和心室短轴缩短率升高,左心室舒张末期内径和左心室收缩末期内径降低,T_(2~5)时TWL延长,MWT升高,脊髓背角Iba1表达下调(P<0.05)。结论小鼠CHF后慢性疼痛可能与脊髓小胶质细胞活化有关。

Objective To evaluate the role of spinal cord microglia in chronic pain after chronic heart failure(CHF)in mice.Methods Eighteen SPF healthy male C57BL/6 mice,aged 8-12 weeks,weighing 20-25 g,were divided into 3 groups(n=6 each)using a random number table method:sham operation group(Sham group),CHF group,and CHF+microglia inhibitor PLX3397 group(CHF+PLX group).The model of chronic heart failure was prepared by ligating the anterior descending branch of the left coronary artery in anesthetized mice.Mice were continuously fed a PLX3397-containing diet from 7 days before preparing the model to 28 days after preparing the model in CHF+PLX group.The cardiac function was evaluated using echocardiography at 28 days after surgery.The mechanical paw withdrawal threshold(MWT)and thermal paw withdrawal latency(TWL)were measured on 1 day before developing the model(T_(0))and 1,3,7,14 and 28 days after developing the model(T_(1-5)).The mice were sacrificed under deep anesthesia after the pain threshold was measured at T_(5),and the spinal cord tissues of the lumbar segment(T_(2-6) and L_(4-6))were removed for determination of the expression of microglial marker Iba1 in the spinal dorsal horn(by immunofluorescence method).Results Compared with Sham group,the left ventricular ejection fraction and left ventricular short axis shortening rate were significantly decreased,and the left ventricular internal diameter at end-diastole and the left ventricular internal diameter at end-systole were increased,the TWL was shortened and MWT was decreased at T_(4-5),and the expression of Iba1 in the spinal dorsal horn was up-regulated in CHF group(P<0.05).Compared with CHF group,the left ventricular ejection fraction and left ventricular short axis shortening rate were significantly increased,and the left ventricular internal diameter at end-diastole and the left ventricular internal diameter at end-systole were decreased,the TWL was prolong and MWT was increased at T_(2-5),and the expression of Iba1 in the spinal dorsal horn was down-regulated in CHF+PLX group(P<0.05).Conclusions The chronic pain after CHF may be related to microglial activation in the spinal cord of mice.