Aims: Communication within glial cells acts as a pivotal intermediary factor in modulating neuroimmune pathology. Meanwhile, an increasing awareness has emerged regarding the detrimental role of glial cells and neuroinflammation in morphine tolerance (MT). This study investigated the influence of crosstalk between astrocyte and microglia on the evolution of morphine tolerance.
Methods: Sprague-Dawley rats were intrathecally treated with morphine twice daily for 9 days to establish morphine-tolerant rat model. Tail-flick latency test was performed to identify the analgesic effect of morphine. The role of microglia, astrocyte and C3-C3aR axis in morphine tolerance were elucidated by real-time quantitative polymerase chain reaction, Western blot, and immunofluorescence.
Results: Chronic morphine treatment notably promoted the activation of microglia, upregulated the production of proinflammatory mediators (interleukin-1 alpha (IL-1α), tumor necrosis factor alpha (TNFα), and complement component 1q (C1q)). Simultaneously, it programed astrocytes to a pro-inflammatory phenotype (A1), which mainly expresses complement 3 (C3) and serping1. PLX3397 (a colony-stimulating factor 1 receptor (CSF1R) inhibitor), Compstain (a C3 inhibitor) and SB290157(a C3aR antagonist) could reverse the above pathological process and alleviate morphine tolerance to different extents.
Conclusion: Our findings identify C3-C3aR axis as an amplifier of microglia-astrocyte crosstalk, neuroinflammation and a node for therapeutic intervention in morphine tolerance.
Keywords: A1 astrocyte; C3/C3aR; microglia‐astrocyte crosstalk; morphine tolerance.
© 2025 The Author(s). CNS Neuroscience & Therapeutics published by John Wiley & Sons Ltd.