脊髓星形胶质细胞通过调控Cx43-JNK通路介导吗啡耐受

Spinal astrocytes mediate morphine antinociceptive tolerance by regulating Cx43-JNK pathway in rats

目的探讨脊髓星形胶质细胞是否通过调控Cx43-JNK通路介导大鼠慢性吗啡耐受。方法采用SD成年大鼠,连续7 d鞘内注射吗啡(15μg/10μl)建立慢性吗啡镇痛耐受动物模型。采用热水甩尾法测定甩尾潜伏期以观察吗啡的镇痛效果。应用Western blot法检测脊髓Cx43、磷酸化JNK(p-JNK)、磷酸化c-Jun(p-c-Jun)和GFAP的表达;免疫组织荧光染色法检测脊髓GFAP的免疫反应性。结果在吗啡耐受形成的过程中,慢性鞘内注射吗啡引起大鼠脊髓GFAP表达逐渐增多,吗啡耐受时脊髓p-JNK、p-c-Jun和Cx43的表达明显增多;氟代柠檬酸(Fluorocitric acid,1 nmol/10μL)可以拮抗吗啡镇痛耐受,并且明显地抑制慢性吗啡所致的脊髓Cx43的上调,以及JNK及c-Jun的激活。结论脊髓Cx43-JNK通路参与星形胶质细胞介导的大鼠慢性吗啡镇痛耐受。

Objective To explore whether the spinal astrocytes mediate chronic morphine antinociceptive tolerance by regulating connexin 43 （Cx43）-c-Jun-N-terminal kinase （JNK） pathway in rats. Methods Morphine （ 15 μg/10 μL） was administrated intrathecally for consecutive 7 days to establish the model of chronic analgesic tolerance to morphine in the adult male Sprague-Dawley （SD） rats. Hot-water tail flick test was used to assess the analgesic efficacy. Western blot assay was applied to detect the expressions of Cx43, phosphorylated （p） -JNK, p-c-Jun and GFAP. Immunoreactivity （IR） of GFAP in the spinal cord was tested by immunofluorescence assay. Results With the development of morphine tolerance, GFAP was gradually upregulated in the lumbar spinal cord of rats. Chronic morphine treatment remarkably increased the expression of the spinal p-JNK, p-c-Jun and Cx43. Coadministration of fluorocitric acid （FC, a specific inhibitor of astrocytes, 1 nmol/10 μL） with morphine obviously attenuated not only morphine antinociceptive tolerance, but also the up-regulation of spinal Cx43, as well as the activations of the JNK and c-Jun induced by chronic morphine tolerance. Conclusion The spinal Cx43-JNK pathway contributes to astrocytes mediated morphine antinociceptive tolerance in rats.