维拉帕米对瑞芬太尼诱发切口痛大鼠痛觉过敏时脊髓背角钾氯共转运体2表达的影响

Effect of verapamil on expression of K＋＆#183;Cl-cotransporter 2 in spinal dorsal horns during remifentanil-induced hyperalgesia in a rat model of incisional pain

目的 评价维拉帕米对瑞芬太尼诱发切口痛大鼠痛觉过敏时脊髓背角钾氯共转运体2（KCC2）表达的影响.方法 清洁级健康成年雄性SD大鼠32只,6-7周龄,体重250- 300 g,采用随机数字表法分为4组（n=8）：对照组（C组）皮下泵注生理盐水;切口痛组（Ⅰ组）制备大鼠切口痛模型;切口痛＋瑞芬太尼＋维拉帕米组（I＋R＋V组）制备切口痛模型前10 min腹腔注射维拉帕米5mg/kg;切口痛＋瑞芬太尼组（I＋R组）和I＋R＋V组制备切口痛模型同时皮下泵注瑞芬太尼80μg·kg^-1·h^-1,泵注时间30 min.于模型制备前1 d（T0）、制备后2、6、24和48 h（T1-4）时采用von Frey纤维丝测定机械缩足反应阈（MWT）.于T4时测定MWT结束后处死大鼠取脊髓腰膨大,采用免疫荧光法检测KCC2的表达.结果 与C组比较,其余组T1-4时MWT降低,脊髓KCC2表达下调（P〈0.05）;与Ⅰ组比较,I＋R组T1-4时MWT降低,脊髓KCC2表达下调（P〈0.05）;与I＋R组比较,I＋R＋V组T1-4时MWT升高,脊髓KCC2表达上调（P〈0.05）.结论 维拉帕米减轻瑞芬太尼诱发切口痛大鼠痛觉过敏的机制与上调脊髓KCC2表达有关.

Objective To evaluate the effect of verapamil on the expression of K＋-Cl-cotransporter 2 （KCC2） in spinal dorsal horns during remifentanil-induced hyperalgesia in a rat model of incisional pain.Methods Thirty-two pathogen-free healthy adult male Sprague-Dawley rats,aged 6-7 weeks,weighing 250-300 g,were divided into 4 groups （n=8 each） using a random number table：control group （group C）,incisional pain group （group Ⅰ）,incisional pain plus remifentanil plus verapamil group （group I＋R＋ V） and incisional pain plus remifentanil group （group I＋R）.Normal saline was subcutaneously infused in group C.A 1 cm long incision was made in the plantar surface of the right hindpaw in anesthetized rats in group Ⅰ.Verapamil 5 mg/kg was intraperitoneally injected at 10 min before establishment of the incisional pain model in group I＋R＋V.In I＋R and I＋R＋V groups,the model of incisional pain was established,and remifentanil was subcutaneously infused for 30 min at a rate of 80 μg · kg^-1 · h^-1 simultaneously.The mechanical paw withdrawal threshold （MWT） to yon Frey filament stimulation was measured at 1 day before establishment of the model （T0） and 2,6,24 and 48 h after establishment of the model （T1-4）.The rats were sacrificed after measurement of MWT at T4,and the lumbar enlargement segments of the spinal cord were harvested for determination of the expression of KCC2 by immunofluorescence.Results Compared with group C,the MWT was significantly decreased at T1-4,and the expression of KCC2 was down-regulated in the other groups （P〈0.05）.Compared with group Ⅰ,the MWT was significantly decreased at T1-4,and the expression of KCC2 was down-regulated in group I＋R （P〈0.05）.Compared with group I＋R,the MWT was significantly increased at T1-4,and the expression of KCC2 was up-regulated in group I＋R＋V （P〈0.05）.Conclusion The mechanism by which verapamil reduces remifentanil-induced hyperalgesia is related to up-regulation of the expression of KCC2 in spinal dorsal horns in a rat mnodel of incisional pain.