Ajuga bracteosa is a famous folk medicine in Taiwan. This research was to investigate the ameliorative effect of crude ethanol extract of A.bracteosa (ABEE) on osteopenia in ovariectomized (OVX) rats and the mechanism through in vitro experiments.
All of rats were divided into sham and OVX groups. The OVX rats were allowed to lose bone for 4 weeks. At 4th week post OVX operation, the OVX rats were dived into four groups treated with water, ABEE (400, 1200 mg/kg, daily, orally) and alendronate (2.5 mg/kg, p.o., 3 times per week) for 12 weeks. ABEE and alendronate decreased plasma levels of C-terminal telopeptides type I collagen and alkaline phosphatase. ABEE and alendronate increased the bone density and calcium content in the femur of OVX rats. The micro-CT analysis indicated the ratio of trabeculae bone volume to tissue volume and trabeculae number of ABEE and alendronate treated groups were higher than OVX group. The histomorphometric analysis also showed that ABEE and alendronate treatments suppressed the osteoclast surface per bone surface in the tibia of OVX rats. ABEE and alendronate could also increase the OVX-induced decrease in bending energy of femurs.
It is found in this experiment that all of the A. bracteosa fractions could inhibit osteoclast differentiation induced by receptor activator nuclear factor kappa B (RANKL), with the fraction-IV in chloroform layer (ABCE4) being the most active. Receptor activator nuclear factor kappa B (RANKL) induced osteoclastogenesis through NF-κB and MAPKs pathways in bone marrow stromal cells and murine macrophage cell line RAW264.7 cells. This study was found ABCE4 could markedly suppressed NF-κB and AP-1 expressions which induced by RANKL to decrease osteoclastogenesis.
In conclusion, oral administration of ABE could suppress osteoporosis in OVX rats, the mechanism may through inhibit osteoclastogenesis led to decrease bone mass loss in OVX rats.
