地佐辛对切口痛大鼠中脑导水管周围灰质神经元c-fos表达的影响

Effect of dezocine on c-fos expression in neurons in midbrain periaqueductal gray in a rat model of incisional pain

目的 评价地佐辛对切口痛大鼠中脑导水管周围灰质神经元c-fos表达的影响.方法 清洁级健康成年雄性Wistar大鼠36只,体重250～ 300 g,采用随机数字表法分为3组（n=12）：对照组（C组）仅给予麻醉而不手术;切口痛组（I组）切口痛模型制备前15 min尾静脉注射0.9％氯化钠溶液2 ml;地佐辛组（D组）切口痛模型制备前15 min尾静脉注射地佐辛1 mg/kg（0.9％氯化钠溶液稀释至2 ml）.于术前24 h（T0）、术后2、6和24 h（T1～3）时测定机械缩足反应阈（MWT）和累积痛评分,T3时痛阈测定后处死大鼠,取全脑,采用免疫组化法检测中脑导水管周围灰质神经元c-fos表达.结果 与C组比较,I组和D组T1～3时MWT降低,累积痛评分升高,中脑导水管周围灰质神经元c-fos表达上调（P＜0.05）;与I组比较,D组T1～3时MWT升高,累积痛评分降低,中脑导水管周围灰质神经元c-fos表达下调（P＜0.05）.结论 地佐辛通过抑制中脑导水管周围灰质神经元c-fos表达减轻大鼠切口痛.

Objective To evaluate the effect of dezocine on the c-fos expression in neurons in the midbrain periaqueductal gray in a rat model of incisional pain.Methods Thirty-six pathogen-free healthy adult male Wistar rats,weighing 250-300 g,were divided into 3 groups （n =12 each） using a random number table：control group （group C）,incisional pain group （group I） and dezocine group （group D）.A 1 cm longitudinal incision was made through skin,fascia and muscle of the plantar aspect of the right hind paw in sevoflurane-anesthetized rats.In group C,the rats were only anesthetized and underwent no operation.In group I,0.9% sodium chloride solution 2 ml was injected via the caudal vein at 15 min before the model was established.In group D,dezocine 1 mg/kg （diluted to 2 ml in 0.9% sodium chloride solution） was injected via the caudal vein at 15 min before the model was established.At 24 h before operation （T0） and 2,6 and 24 h after operation （T1-3）,the mechanical paw withdrawal threshold （MWT） and cumulative pain score were measured.After measurement of the pain threshold at T3,the whole brain was removed for determination of the c-fos expression in neurons in the midbrain periaqueductal gray by immunohistochemistry.Results Compared with group C,the MWT was significantly decreased,cumulative pain scores were increased,and the expression of c-fos in neurons in the midbrain periaqueductal gray was upregulated at T1-3 in I and D groups （P〈0.05）.Compared with group I,the MWT was significantly increased,the cumulative pain score was decreased,and the expression of c-fos protein in neurons in the midbrain periaqueductal gray was down-regulated at T1.3 in group D （P〈0.05）.Conclusion Dezocine mitigates incisional pain through inhibiting the expression of c-fos in neurons in the midbrain periaqueductal gray of rats.