Although they represent the cornerstone of analgesic therapy, opioids, such as morphine, are limited in efficacy by drug tolerance, hyperalgesia and other side effects. Activation of microglia and the consequent production of proinflammatory cytokines play a key pathogenic role in morphine tolerance, but the exact mechanisms are not well understood. This study aimed to investigate the regulatory mechanism of epidermal growth factor receptor (EGFR) on microglial activation induced by morphine in mouse microglial BV-2 cells. In this research, BV-2 cells were stimulated with morphine or pretreated with AG1478 (an inhibitor of EGFR). Expression levels of cluster of differentiation molecule 11b (CD11b), EGFR, and phospho-EGFR were detected by immunofluorescence staining. Cell signaling was assayed by Western blot. The migration ability of BV-2 cells was tested by Transwell assay. The production of interleukin-1beta (IL-1β) and tumor necrosis factor-alpha (TNF-α) in the cell supernatant was determined by ELISA. We observed that the expression of CD11b induced by morphine was increased in a dose- and time- dependent manner in BV-2 cells. Phosphorylation levels of EGFR and ERK1/2, migration of BV-2 cells, and production of IL-1β and TNFα were markedly enhanced by morphine treatment. The activation, migration, and production of proinflammatory cytokines in BV-2 cells were inhibited by blocking the EGFR signaling pathway with AG1478. The present study demonstrated that the EGFR/ERK signaling pathway may represent a novel pharmacological strategy to suppress morphine tolerance through attenuation of microglial activation.

中文翻译：

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吗啡通过上调 EGFR/ERK 信号通路促进小胶质细胞活化。

尽管它们代表了镇痛治疗的基石，但吗啡等阿片类药物的疗效受到药物耐受性、痛觉过敏和其他副作用的限制。小胶质细胞的激活和随之而来的促炎细胞因子的产生在吗啡耐受中起着关键的致病作用，但确切的机制尚不清楚。本研究旨在探讨表皮生长因子受体（EGFR）对吗啡诱导小鼠小胶质细胞BV-2细胞小胶质细胞活化的调控机制。在这项研究中，BV-2 细胞用吗啡刺激或用 AG1478（EGFR 抑制剂）预处理。通过免疫荧光染色检测分化分子簇 11b (CD11b)、EGFR 和磷酸化 EGFR 的表达水平。通过蛋白质印迹分析细胞信号传导。Transwell实验检测BV-2细胞的迁移能力。通过ELISA测定细胞上清液中白细胞介素-1β（IL-1β）和肿瘤坏死因子-α（TNF-α）的产生。我们观察到吗啡诱导的 CD11b 表达在 BV-2 细胞中以剂量和时间依赖性方式增加。吗啡处理显着增强了 EGFR 和 ERK1/2 的磷酸化水平、BV-2 细胞的迁移以及 IL-1β 和 TNFα 的产生。通过用 AG1478 阻断 EGFR 信号通路来抑制 BV-2 细胞中促炎细胞因子的激活、迁移和产生。本研究表明，EGFR/ERK 信号通路可能代表了一种通过减弱小胶质细胞激活来抑制吗啡耐受的新药理学策略。通过ELISA测定细胞上清液中白细胞介素-1β（IL-1β）和肿瘤坏死因子-α（TNF-α）的产生。我们观察到吗啡诱导的 CD11b 表达在 BV-2 细胞中以剂量和时间依赖性方式增加。吗啡处理显着增强了 EGFR 和 ERK1/2 的磷酸化水平、BV-2 细胞的迁移以及 IL-1β 和 TNFα 的产生。通过用 AG1478 阻断 EGFR 信号通路来抑制 BV-2 细胞中促炎细胞因子的激活、迁移和产生。本研究表明，EGFR/ERK 信号通路可能代表了一种通过减弱小胶质细胞激活来抑制吗啡耐受的新药理学策略。通过ELISA测定细胞上清液中白细胞介素-1β（IL-1β）和肿瘤坏死因子-α（TNF-α）的产生。我们观察到吗啡诱导的 CD11b 表达在 BV-2 细胞中以剂量和时间依赖性方式增加。吗啡处理显着增强了 EGFR 和 ERK1/2 的磷酸化水平、BV-2 细胞的迁移以及 IL-1β 和 TNFα 的产生。通过用 AG1478 阻断 EGFR 信号通路来抑制 BV-2 细胞中促炎细胞因子的激活、迁移和产生。本研究表明，EGFR/ERK 信号通路可能代表了一种通过减弱小胶质细胞激活来抑制吗啡耐受的新药理学策略。