Glycyrrhizin (GLY) diminishes effects of PMMA particles on the size of osteolytic calvarial lesions in aged mice. (A) Expression of osteoclastogenesis-related Oc-stamp, Dc-stamp, and Acp 5/Trap genes in the dissected calvarial tissues of control (no particle placed) and PMMA particle-induced bone lesions of sham and GLY-treated aged wild type (twenty-four-month-old) mice. μ-CT images and histological evaluation of TRAP osteoclasts (B and C) in the PMMA particle-induced calvarial lesions of aged mice that received: Control (no particles), PMMA particles alone, and PMMA/GLY injection. D: The number of TRAP+ osteoclasts measured in a microscopic field (0.01 mm2) of TRAP-stained sections. Because no significant effect of GLY at 20 mg/kg concentration was observed, only a group of mice treated with 200 mg/kg of GLY solution was evaluated by μ-CT and immunohistochemistry. *p < 0.05, **p < 0.01, ***p < 0.001.