鞘内注射吗啡对切口痛大鼠脊髓背角p-αCaMK Ⅱ表达的影响

Effects of intrathecal morphine on p-αCaMK Ⅱ in the spinal cord in a rat model of incisional pain

目的 研究鞘内注射（IT）吗啡对切口痛大鼠脊髓背角磷酸化钙-钙调蛋白依赖性蛋白激酶Ⅱ（p-αCaMKⅡ）表达的影响.方法 雄性SD大鼠32只,随机分为4组（n=8）,分别为假手术组（S组）、切口痛组（IP组）、术前吗啡组和术后吗啡组.按Yaksh法鞘内置管,按Brennan法制备大鼠足底切口痛模型,以von Frey细丝法和热辐射法测定机械缩足反射阈值（MWT）和热刺激缩足反射潜伏期（TWL）,观察大鼠术后2 h时的疼痛行为学变化,应用免疫组织化学和Western blot法观察脊髓背角p-αCaMK Ⅱ表达的变化.结果 与S组比较,IP组大鼠MWT明显降低（P＜0.01）,TWL明显缩短（P＜0.01）.脊髓背角p-αCaMKⅡ阳性神经元数量和蛋白表达明显增加（P＜0.01） 与IP组比较,术前吗啡组和术后吗啡组大鼠的MWT明显升高（P＜0.01）,TWL明显延长（P＜0.01）,术前吗啡组大鼠脊髓背角p-aCaMK Ⅱ阳性神经元数量和蛋白表达明显减少（P＜0.05或P＜0.01）.结论 在大鼠切口痛模型中,术前IT吗啡的抗伤害作用可能与抑制切口痛引起的脊髓背角P-aCaMK Ⅱ表达增加有关.

Objective To investigate the effects of intrathecal（IT） morphine on phospho-calcium/ calmodulin-dependent protein kinase Ⅱ α （p-αCaMK Ⅱ） in the spinal cord in a rat model of incisional pain. Methods Thirty-two male SD rats were randomly divided into four groups （n = 8）.. sham group（group S）, incisional pain group（group IP）, pre-incisional morphine group and post-incisional morphine group. A PE-10 catheter was intrathecally inserted to the lumbar region according to the method of Yaksh. A 1 cm long incision was made in the plantar area of left hindpaw according to the method of Brennan. Pain behavior at 2 h after incision was assessed by mechanical withdrawal threshold（MWT） to von Frey filaments, thermal withdrawal latency（TWL） to radiant heat. The expression of p-αCaMK Ⅱ was assessed by immunohistochemical and western blot analysis. Results Compared with group S, MWT was significantly lower than those in group IP （P〈0.01）. TWL decreased significantly in group IP （P〈0.01） at 2 h after incision. The number of positive cells and protein expression of p-αCaMK Ⅱ was significantly increased in spinal cord in group IP （P〈0.01）. Compared with group IP, MWT increased significantly in pre-incisional and post-incisional morphine group（P〈0.01）. TWL prolonged significantly（P〈0.01）at 2 h after incision. The number of positive cells and protein expression of p-αCaMK Ⅱ was significantly decreased in spinal cord in pre-incisional morphine group（P〈0.05 or P〈0.01）. Conclusion In a rat model of incisional pain,the antinociception of preemptive IT administration of morphine may be associated with inhibition of the expression of p-αCaMK Ⅱ in spinal cord.