Akiyama Y, Hara K, Kobayashi M, Tomiuga T, Nakamura T
Department of Applied Drug Research, Eisai Co., Ltd., Tokyo, Japan.
Jpn J Pharmacol. 1999 May;80(1):67-74. doi: 10.1254/jjp.80.67.
To clarify how vitamin K2 prevents bone loss in vivo, it was given to ovariectomized 20-week-old rats for 2 weeks. Bone mineral density (BMD) in the whole femur and in 7 specific portions (F1 to F7 from the proximal to the distal end) was determined by dual-energy X-ray absorptiometry, and histomorphometry was also performed in proximal tibial metaphysis. Ovariectomy (OVX) resulted in significant decreases in the BMD in the whole femur and the F1, F2, F6 and F7 portions. Histomorphometrical analysis of the tibia showed that the bone volume/tissue volume (BV/TV), trabecular thickness (Tb.Th) and trabecular number (Tb.N) were decreased, while trabecular separation (Tb.Sp) and osteoclast number/bone surface (Oc.N/BS) were increased by OVX. The parameters for bone formation were not changed by OVX. These data indicate that the bone loss within 2 weeks is due to the enhancement of bone resorption. Vitamin K2 at 50 mg/kg inhibited the decrease in the BMD of the whole femur together with the F6 and F7 portions. Vitamin K2 also inhibited the decrease in Tb.N and the increases in Tb.Sp, Oc.N/BS and osteoclast surface/bone surface (Oc.S/BS) caused by OVX. These results suggest that vitamin K2 prevents bone loss through the inhibition of bone resorption and osteoclast formation in vivo.
为阐明维生素K2在体内预防骨质流失的机制，将其给予20周龄的去卵巢大鼠，持续2周。通过双能X线吸收法测定整个股骨以及7个特定部位（从近端到远端的F1至F7）的骨密度（BMD），并对胫骨近端干骺端进行组织形态计量学分析。去卵巢（OVX）导致整个股骨以及F1、F2、F6和F7部位的骨密度显著降低。胫骨的组织形态计量学分析表明，骨体积/组织体积（BV/TV）、小梁厚度（Tb.Th）和小梁数量（Tb.N）降低，而去卵巢使小梁间距（Tb.Sp）和破骨细胞数量/骨表面积（Oc.N/BS）增加。去卵巢对骨形成参数没有影响。这些数据表明，2周内的骨质流失是由于骨吸收增强所致。50mg/kg的维生素K2可抑制整个股骨以及F6和F7部位骨密度的降低。维生素K2还可抑制去卵巢引起的Tb.N降低以及Tb.Sp、Oc.N/BS和破骨细胞表面积/骨表面积（Oc.S/BS）的增加。这些结果表明，维生素K2通过抑制体内骨吸收和破骨细胞形成来预防骨质流失。
