Discussion
Our findings indicate a significant link between NLRP3 inflammasome activation and morphine tolerance, suggesting that NLRP3 contributes to the transformation of astrocytes to the A1 phenotype. Inhibiting NLRP3 inflammasome activation holds promise in reversing astrocyte phenotype changes, potentially mitigating morphine tolerance.
Methods
A model of morphine tolerance was established by administering morphine intrathecally for seven consecutive days. To inhibit NLRP3 inflammasome activation, we coadministered MCC950, a selective NLRP3 inhibitor. Thermal withdrawal latency was used to assess tolerance development. Protein and mRNA levels of GFAP, IL-18, NLRP3, C3 (A1 marker), and S100A10 (A2 marker) in the spinal cord were measured using Western blotting (WB) and real-time quantitative polymerase chain reaction (RT-qPCR). Immunofluorescence was employed to assess the colocalization of C3 and GFAP.
Results
Seven days of morphine administration induced tolerance, which was associated with increased levels of GFAP, IL-18, NLRP3, and C3, and a decreased level of S100A10. Coadministration of morphine and MCC950 significantly slowed the development of morphine tolerance and reversed changes in NLRP3, IL-18, GFAP, C3, and S100A10 protein levels.