Aspirin treatment inhibits osteoclast activities.

<p>(A) OVX mice have increased levels of RANKL and type I collagen C-terminal telopeptides and decreased levels of OPG in blood serum as compared to sham mice. Aspirin treated OVX mice (OVX+A) showed a significant decreased levels of RANKL and type I collagen C-terminal telopeptides along with increased levels OPG in blood serum. The graph represents mean±SD (n = 5; [<i>P</i><0.01 vs. Sham; #<i>P</i><0.05 vs. OVX). (B) TRAP staining confirmed that OVX mice had increased number of TRAP positive cells in epiphysis and trabecular bone areas of the distal femurs as compared to sham mice. Administration of aspirin for three months resulted in a significant decrease in number of TRAP positive cells (OVX+A) in the epiphysis and trabecular bone areas (n = 6; [[[<i>P</i><0.005 vs. Sham; ###<i>P</i><0.005 vs. OVX). (C) <i>Ex vivo</i> co-culture bone marrow cells or spleen cells with osteoblastic cells revealed that <i>in vitro</i> aspirin treatment inhibits the formation of TRAP-positive multinuclear cells (MNCs) in a dose dependent manner (2–200 µg/ml). The graph represents mean±SD (n = 5; [[[<i>P</i><0.005 vs. ASP 0 µg/mL). (D) RANKL-induced osteoclastogenesis was partially blocked by aspirin treatment at 50 µg/ml as seen a significantly decreased number of TRAP-positive osteoclasts in aspirin treated group (ASP 50). The graph represents mean±SD (n = 5; [[[<i>P</i><0.005 vs. ASP 0 µg/mL).