Although it has been clearly shown that Pueraria mirifica and its phytoestrogens can mimic estrogen in preventing bone loss, as osteoporosis is an asymptomatic disease, the therapeutic effects of P. mirifica should be acknowledged. In this study, 6-month-old female rats were ovariectomized, kept for 4 weeks to induce bone loss, divided into five groups, and treated with P. mirifica at doses of 0, 5, 25, and 50 mg/kg BW/day (PM0, PM5, PM25, and PM50 groups, respectively) or 7 mg/kg BW/day of puerarin (PU group) for 12 weeks. Only the trabecular bone mineral densities (BMDs) of tibia metaphysis (at the 12th, 14th, and 16th week) and total and trabecular BMDs of L4 (at the 16th week) of the PM50 group were significantly higher than those of the PM0 group. However, the BMDs of tibia metaphysis and L4 at the 16th week of the study period were kept significantly lower than those of the 0 week, and the BMD was also significantly lower than that of the 4th week for tibia metaphysis. The trabecular bone area (BV/TV), trabecular number (Tb.N), and osteoblast surface (Ob.S/BS) were significantly higher, and trabecular space (Tb.Sp) was significantly lower in the PM50 group, as compared with those of the PM0 group. This study indicates that P. mirifica could be used as an anti-osteoporotic agent for postmenopausal women. Since P. mirifica could mainly retain bone mass at the levels before bone loss is initiated, the use of other anabolic agents in combination with P. mirifica is recommended for osteoporotic patients.
Keywords: Bone loss; Osteoblast; Osteoclast; Phytoestrogens.