Effect of vitamin K2 on lumbar vertebral bone: histomorphometric analyses in experimental osteoporotic rats

The in-vivo effect of vitamin K2 on bone metabolism was investigated by histochemical and morphometric methods, using an animal model of osteoporosis. Eighteen female Wistar rats were divided into three groups. Rats in group A had sham ovariectomies, group B were ovariectomized, and group C were ovariectomized and received vitamin K2, at 10mg/kg per day, injected subcutanously. The lumbar vertebral bones were evaluated 8 weeks after the operation by a modified tetrachrome method after decalcification. Mineralized bone areas, osteoid, and deficectively mineralized bone areas in group B were markedly decreased compared with findings in group A, but these features in group C were not severely decreased. There was no significant difference in total bone areas and total bone volumes among the three groups. Accordingly, it appeared that vitamin K2 had an effect in reducing mineralized bone loss after the ovariectomy. In conclusion, vitamin K2 is thought to be beneficial for the properties of bone microarchitecture in the condition of osteoporosis.