Puerariae radix prevents bone loss in castrated male mice

Puerariae radix (PR) is one of the earliest and most important crude herbs used in Chinese medicine for various medicinal purposes. PR contains a high amount of isoflavonoids, such as daidzein and genistein, which are known to prevent bone loss induced by estrogen deficiency. We have demonstrated that PR not only completely prevents bone loss but also significantly increases the bone mass at high doses in ovariectomized mice without exhibiting estrogenic action in the uterus. In this study, we examined whether PR exhibits effects on bone loss in androgen-deficient male mice similar to estrogen-deficient female mice. Male mice were orchidectomized (ORX) and fed a diet containing low, middle, and high doses (5%, 10%, and 20% of diet, respectively) of PR or normal diet with subcutaneous administration of 17β-estradiol (E2, 0.03 μg/d; Sigma, St Louis, Mo), for 4 weeks. In ORX mice, the seminal vesicle weight decreased markedly, and it was not affected by the administration of any doses of PR and E2. The bone mineral density (BMD) of the whole femur was significantly decreased by ORX, and the decrease in BMD was completely prevented by intake of the diet with the low dose of PR. Intake of the diet with the middle dose of PR further normalized BMD in ORX mice. Furthermore, the high dose of PR administration (PR20) significantly increased BMD in ORX mice, and the potency was similar to that of E2. Morphometric analysis of the femoral metaphysis showed that intake of the diet with the low dose of PR completely prevented the decrease in bone volume/tissue volume and trabecular number and restored the increase in trabecular separation in ORX mice. In addition, intake of the diet with the high dose of PR further increased bone volume/tissue volume and trabecular number and decreased trabecular separation in ORX mice. These results propose the possibility that estrogenic Chinese herbs such as PR can be one of the candidates for the treatment or prevention of osteoporosis in elderly men with hypogonadism.