EFFECT OF VITAMIN-K-2 (MENATETRENONE) ON OSTEOCLAST-LIKE CELL-FORMATION IN MOUSE BONE-MARROW CULTURES

The effects of menatetrenone, a vitamin K-2 homologue, on osteoclast-like cell formation in mouse bone marrow culture were investigated. After 7 days of incubation, menatetrenone at 10(-6) M, 3 X 10(-6) M and 10(-5) M dose dependently inhibited the tartrate-resistant acid phosphatase-positive multinucleated cell formation induced by 1,25-dihydroxyvitamin D-3 (1,25(OH)(2)D-3). The addition of menatetrenone for the last 3 days of the 7-day incubation period was required to inhibit formation of multinucleated cells in response to 1,25(OH)(2)D-3. Moreover, the addition of 1,25(OH)(2)D-3 for the last 3 days was essential for multinucleated cell formation, and this activity was markedly inhibited by the simultaneous addition of menatetrenone. The inhibitory effects of menatetrenone on multinucleated cell formation may contribute to its ameliorative action on bone loss in vivo, and may indicate a new mechanism of vitamin K-2 activity in bone metabolism