脊髓小胶质细胞激活参与吗啡诱导瘙痒的机制

ACTIVATION OF MICROGLIA IN SPINAL CORD INVOLVED IN MORPHINE INDUCED ITCH

摘要:

目的： 探讨脊髓小胶质细胞激活对吗啡诱导瘙痒的调控机制。方法：C57BL/6J雄性小鼠，重20-30g，随机分为3组：正常对照组，吗啡组，吗啡加米诺环素组。每组12只，其中6只用于行为学测试，6只用于形态学及分子生物学检测，共36只。每次鞘内注射给药后即刻，连续记录瘙痒行为学30min。隔三天后再次注射吗啡或米诺环素，15min后取出L4-S1节段脊髓进行免疫印迹及免疫荧光检测。 结果：鞘内注射吗啡后瘙痒次数明显增加，脊髓背角Ⅰ-Ⅴ层小胶质细胞激活标志物OX-42表达增加，激活的小胶质细胞数量增多、p-p38表达显著增多（P<0.05)。与单独鞘内注射吗啡组相比，米诺环素处理后小鼠瘙痒行为学明显减少，同时激活的小胶质细胞数量及脊髓CD11b蛋白表达显著降低(P<0.05)，p-p38阳性细胞数量减少(P<0.05)。 结论: 吗啡诱导的瘙痒与脊髓背角小胶质细胞激活有关，可能通过激活p38MAPK通路参与吗啡诱导瘙痒的产生。

Abstract:

Objective: To investigate the regulation mechanism of microglia activation in morphine-induced scratch(MIS). Methods: C57BL/6J male mice weighting 20-30 g were randomly divided into 3 groups: normal control group, morphine group, morphine plus minocycline group. 12 mice in each group, 6 of which were used for behavioral testing and 6 were divided equally for morphological and molecular biological testing, respectively. After intrathecal injection, the scratching behavior was recorded immediately and continuously for 30 minutes. Three days later, the mice were repeatly injection of morphine or minocycline (MC), and the L4-S1 segmental spinal cord was removed after 15min of injection for immunoblotting and immunofluorescence detection. Results: The scratching numbers increased significantly after intrathecal injection of morphine, and the expression of OX-42, a microglia activation marker in the I-V layer of the spinal dorsal horn, increased, and the expression of phosphorylated-p38 increased significantly(P<0.05). Compared with the morphine group, the scratching behavior and the expression of activated microglia were significantly reduced after intrathecal injection of minocycline in MIS(P<0.05). In the morphine group, the expression of microglia, the CD11b protein and phosphorylated-p38 were significantly higher than those in the minocycline group(P<0.05). Conclusion: Morphine-induced scratches are associated with microglia activation in the spinal cord which may activated p-p38 pathway participating in morphine-induced scratching.