Chemokine ligand 2 in the trigeminal ganglion regulates pain induced by experimental tooth movement

ABSTRACT Objective: To test the hypothesis that the chemokine ligand 2/chemokine receptor 2 (CCL2/CCR2) signaling pathway plays an important role in pain induced by experimental tooth movement. Materials and Methods: Expression of CCL2/CCR2 in the trigeminal ganglion (TG) was determined by Western blotting 0 hours, 4 hours, 1 day, 3 days, 5 days, and 7 days after tooth movement. CCL2 localization and cell size distribution were revealed by immunohistochemistry. The effects of increasing force on CCL2 expression and behavioral changes were investigated. Furthermore, the effects of CCL2/CCR2 antagonists on these changes in pain behaviors were all evaluated. Exogenous CCL2 was injected into periodontal tissues and cultured TG neurons with different concentrations, and then the pain responses or c-fos expression were assessed. Results: Experimental tooth movement led to a statistically significant increase in CCL2/CCR2 expression from day 3 to day 7, especially in small to medium-sized TG neurons. It also tri...