(A and B) RANKL and OPG expression was determined by western blot analysis of total lysates from the periodontal bone of aged animals (Young, Adult, and Old) and Old animals treated for 8 weeks with 42ppm rapamycin (eRAPA). The periodontal bone within both the NIA-UW and JAX Colonies showed an increased expression of RANKL while 8 weeks of rapamycin treatment ameliorated the increased RANKL expression. Each lane represents individual periodontal bone samples. (C) Quantification of RANKL/OPG of the NIA-UW western blot analysis. (D) Representative histological sections of the alveolar bone furcation that have undergone TRAP azo-dye staining with FastGreen counterstain. (E) Enumeration of TRAP+ cells within the periodontal bone from two-independent observers reveals an increase number of TRAP+ cells with age and diminishes with rapamycin treatment. Statistical analysis was completed with unpaired t-test, with significance set to p<0.05. *p<0.05, **p<0.01, ***p<0.005.