Interesting, recent studies have suggested a possibility that transcriptional factor NF-kappa B may play a functional role in the survival of mouse osteoclasts. However, it has not been known. whether NF-kappa B is involved in apoptosis of and bone resorption by mature osteoclasts. Thus, using NF-kappa B inhibitors, we examined the functional role of NF-kappa B in the induction of apoptosis in rabbit mature osteoclasts. PDTC, a potent inhibitor of NF-kappa B, stimulated markedly apoptosis of the osteoclasts and inhibited bone resorption by these cells. These effects also was observed when three other inhibitors of NF-kappa B were used. And a gel mobility shift assay showed that PDTC also inhibited NF-kappa B binding to its consensus sequence in the cells. These results suggest a regulatory role for NF-kappa B in apoptosis in and bone resorption by rabbit mature osteoclasts. (C) 1997 Federation of European Biochemical Societies.