鞘内注射米诺环素对骨癌痛大鼠脊髓水平酸敏感离子通道蛋白1a表达的影响

目的 探讨鞘内注射米诺环素对骨癌痛(bone cancer pain,BCP)大鼠脊髓水平酸敏感离子通道蛋白1a(acidsensing ion channel 1a,ASIC1a)表达的影响. 方法 选择雌性SD大鼠(体重180～220 g),采用随机数字表法分为4组:假手术+生理盐水组(Ⅰ组)、假手术+米诺环素组(Ⅱ组)、BCP+米诺环素组(Ⅲ组)和BCP+生理盐水组(Ⅳ组).①于造模前1d及造模后3、5、7、10、14、18d测定大鼠(每组选8只)自由行走痛行为评分,同时测定大鼠机械缩足反射阈值(paw withdrawalmechanical threshold,PWMT)至14 d;②于造模前1d及造模后3、5、7、10、14、21 d同一时段随机处死大鼠(每组选4只),取腰段脊髓,采用Western blot法检测ASIC1a的表达;③于造模后1、3、7、14、21 d,采用免疫荧光技术观察大鼠(每组选4只)患侧脊髓ASIC1a和小胶质细胞标记物离子钙接头蛋白分子1(ionized calcium binding adapter 1,Iba-1)]免疫反应阳性产物的共表达. 结果 ①与Ⅰ组和Ⅱ组比较,造模后14、18dⅢ组、Ⅳ组自由行走痛行为评分明显升高(P＜0.01);造模后5d时Ⅲ组、Ⅳ组PWMT开始下降(P＜0.01),至7、14 d维持在低水平(P＜0.01);与Ⅳ组比较,Ⅲ组PWMT在造模后7、10、14 d均较高(P＜0.05).②与Ⅰ组和Ⅱ组比较,Ⅲ组、Ⅳ组从造模后3d开始ASIC1a表达上调(P＜0.01),于14 d达到高峰(P＜0.01);与Ⅳ组比较,Ⅲ组在造模后5、7、10、14、21 d ASIC1a表达量均较低(P＜0.05).③与Ⅰ组和Ⅱ组比较,Ⅲ组、Ⅳ组在造模后3、7、14、21 d脊髓背角ASIC1a阳性细胞数和活化的小胶质细胞数均较高(P＜0.05),未发现双标细胞;与Ⅳ组比较,Ⅲ组大鼠脊髓ASIC1a阳性细胞数和活化的小胶质细胞数均明显降低(P＜0.01). 结论 大鼠BCP的形成和维持可能与ASIC1a有关;鞘内注射米诺环素可以减轻大鼠的机械性痛觉过敏,其作用可能是通过抑制脊髓ASIC1a的表达实现的.

The role of intrathecal injection of minocycline on the expression of acid-sensing ion channel 1a in the spinal cord of rats with bone cancer pain

Objective To discuss the effects of intrathecal injection of minocycline on the expression of acid-sensing ion channel 1 a (ASIC1a) in the spinal cord of rats with bone cancer pain (BCP).Methods Female SD rats weighting 180 to 220 g were randomly divided into four groups:a sham+normal saline group (group Ⅰ),a sham+minocycline group (group Ⅱ),a BCP+minocycline group (group Ⅲ) and a BCP+normal saline group (group Ⅳ).Free walk-associated pain was scored 1 day before modeling and 3,5,7,10,14 and 18 days after modeling,while paw withdrawal mechanical threshold (PWMT) after mechanical stimulus were determined (n=8).Meanwhile,4 rats in each group were scarified randomly 1 day before modeling and 3,5,7,10,14 and 21 days after modeling.Their lumbar segments of the spinal cord were removed to determine the expression of ASIC1a by Western blotting.Furthermore,the cell with positive ASIC1a and ionized calcium binding adapter 1 (Iba-1) expression in the dorsal horn was observed by immunofluoresence staining 1,3,7,14 and 21 days after modeling (n=4).Results ① Compared with groups Ⅰ and Ⅱ,PWMT in groups Ⅲ and Ⅳ was significantly decreased on day 5 after modeling (P＜0.01),and remained at low levels on days 7 and 14 (P＜0.01).Compared with groups Ⅰ and Ⅱ,free walk-associated pain scores in groups Ⅲ and Ⅳ were significantly increased on days 14 and 18 (P＜0.01).Compared with group Ⅳ,PWMT in group Ⅲ were significantly increased on days 7,10 and 14 after modeling (P＜0.05).② Compared with groups Ⅰ and Ⅱ,the levels of ASIC1a in groups Ⅲ and Ⅳ were significantly increased from day 3 after modeling (P＜0.01) and reached the peak from days 14 to 18(P＜0.01).Compared with group Ⅳ,the level of ASIC1a in group Ⅲ was significantly decreased on days 5,7,10,14 and 18 after modeling (P＜0.05).③ Compared with groups Ⅰ and Ⅱ,the number of ASIC1a-positive cells and activated microglia were significantly increased in group Ⅲ and Ⅳ on days 3,7,14 and 21 after modeling (P＜0.05),without double stained cells.Compared with group Ⅳ,the number of ASIC1a-positive cells and activated microglia were significantly decreased in group Ⅲ (P＜0.01).Conclusions ASIC1a in the spinal cord may be involved in the formation and maintenance of BCP.Intrathecal injection of minocycline can relieve the mechanical pain in rats,which may be achieved by inhibiting the expression of ASIC1a in the spinal cord.