脊髓sigma-1受体在大鼠骨癌痛维持中的作用：与ERK的关系

Role of spinal sigma-1 receptors in maintenance of bone cancer pain in rats： the relationship with ERK

目的 评价脊髓sigma-1受体在大鼠骨癌痛维持中的作用及其与细胞外信号调节激酶（ERK）的关系.方法 实验一 健康雌性SD大鼠24只,体重180 ～ 220 g,采用随机数字表法分为2组：假手术组（S组,n=4）和骨癌痛组（BCP组,n=20）.采用右侧胫骨骨髓腔内接种Walker 256乳腺癌肿瘤细胞的方法制备大鼠骨癌痛模型.S组于接种后第10天,BCP组于接种后第3、5、7、10、14天分别处死4只大鼠,取L4-6脊髓组织,采用Western blot法测定sigma-1受体的表达.实验二健康雌性SD大鼠40只,体重180 ～ 220 g,采用随机数字表法分为4组（n=10）：假手术组（S组）、sigma-1受体拮抗剂BD1047组（BD组）、骨癌痛组（BCP组）和骨癌痛＋BD1047组（BCP＋ BD组）.于接种后第10～ 14天,S组和BCP组鞘内注射生理盐水20μl,BD组和BCP＋ BD组鞘内注射BD1047 120 nmol/20μl,1次/d.于接种前1d及接种后第3、5、7天和第10、12、14天给药后测定机械痛阈,接种后第14天行为学测试结束后处死大鼠,取L4-6脊髓组织,采用Western blot法测定磷酸化ERK（p-ERK）蛋白表达.结果 实验一：与S组相比,BCP组脊髓sigma-1受体表达上调,并在术后第10天达到高峰（P＜0.05）.实验二：与S组相比,BD组各时点机械痛阈和脊髓p-ERK蛋白表达差异无统计学意义（P＞0.05）,BCP组和BCP＋ BD组机械痛阈降低,脊髓p-ERK蛋白表达上调（P＜0.05）;与BCP组相比,BCP＋ BD组鞘内注射BD1047后机械痛阈升高,脊髓p-ERK蛋白表达下调（P＜0.05）.结论 脊髓sigma-1受体可能通过促进ERK的磷酸化参与大鼠骨癌痛的维持.

Objective To evaluate the role of spinal sigma-1 receptors in the maintenance of bone cancer pain （BCP） in rats and the relationship with extracellular signal-regulated kinase （ERK）.Methods Part Ⅰ Twenty-four female Sprague-Dawley rats,weighing 180-220 g,were randomized into 2 groups using a random number table：sham operation group （S group,n =4） and BCP group （n =20）.BCP was induced by inoculating Walker 256 mammary gland carcinoma cells into the medullary cavity of the right tibia.Four rats were sacrificed on day 10 after inoculation in S group or on day 3,5,7,10 and 14 after inoculation in BCP group,and the L4-6 segments of the spinal cord were removed to measure the expression of sigma-1 receptors by Western blot.Part Ⅱ Forty female Sprague-Dawley rats,weighing 180-220 g,were randomized into 4 groups （n =10 each） using a random number table：sham operation group （S group）,sigma-1 receptor inhibitor BD1047 group （BD group）,BCP group,and BCP ＋ BD1047 group （BCP ＋ BD group）.On day 10 to 14 after inoculation,normal saline 20 μl was injected intrathecally once a day in S and BCP groups,or BD1047 120 nmol/20μl was injected intrathecally once a day in BD and BCP ＋ BD groups.Mechanical paw withdrawal threshold （MWT） to yon Frey filament stimulation was measured one day before inoculation,on day 3,5 and 7 after inoculation,and on day 10,12 and 14 after administration.After measurement of MWT on day 14 after inoculation,the rats were sacrificed and the L4-6 segments of the spinal cord were removed to determine the expression of phosphorylated ERK （p-ERK） by Western blot.Results Part Ⅰ Compared with group S,the expression of sigma-1 was significantly up-regulated and peaked on day 10 after operation in group BCP.Part Ⅱ Compared with S group,no significant changes were found in MWT and p-ERK expression at each time point in BD group,and MWT was decreased and p-ERK expression was up-regulated in BCP and BCP ＋ BD groups.Compared with group BCP,after intrathecal injection of BD1047,MWT was significantly increased and the expression of p-ERK was down-regulated in BCP ＋ BD group.Conclusion Spinal sigma-1 receptors are involved in the maintenance of BCP in rats possibly through promoting phosphorylation of ERK.