Preventive effects by traditional Chinese (Kampo) medicines, Unkei-to, Hachimi-jio-gan, and Juzen-taiho-to, on the progress of bone loss induced by ovariectomy in rats were investigated for a period of 49 days. The bone mineral density (BMD) of tibia in ovariectomized (OVX) rats decreased by 20% from those in sham-operated (Sham) rats, with the decrease completely inhibited by the administration of any one of these Kampo medicines or 17beta-estradiol. From scanning electron microscopic (SEM) analyses, the surface of a trabecular bone of tibia in OVX rats had a porous or erosive appearance, whereas that of the same bone in Sham rats was composed of fine particles. The administration of three Kampo medicines and 17beta-estradiol to OVX rats preserved the fine particle surface of the trabecular bone. These results strongly suggest that any of these three gynecological Kampo medicines is as effective as 17beta-estradiol in preventing the development of bone loss induced by ovariectomy in rats.

Royal jelly (RJ) has been used worldwide for many years as medical products, health foods and cosmetics. Since RJ contains testosterone and has steroid hormone-type activities, we hypothesized that it may have beneficial effects on osteoporosis. We used both an ovariectomized rat model and a tissue culture model. Rats were divided into eight groups as follows: sham-operated (Sham), ovariectomized (OVX), OVX given 0.5% (w/w) raw RJ, OVX given 2.0% (w/w) RJ, OVX given 0.5% (w/w) protease-treated RJ (pRJ), OVX given 2.0% (w/w) pRJ, OVX given 17β-estradiol and OVX given its vehicle, respectively. The Ovariectomy decreased tibial bone mineral density (BMD) by 24%. Administration of 17β-estradiol to OVX rats recovered the tibial BMD decrease by 100%. Administration of 2.0% (w/w) RJ and 0.5–2.0% (w/w) pRJ to OVX rats recovered it by 85% or more. These results indicate that both RJ and pRJ are almost as effective as 17β-estradiol in preventing the development of bone loss induced by ovariectomy in rats. In tissue culture models, both RJ and pRJ increased calcium contents in femoral-diaphyseal and femoral-metaphyseal tissue cultures obtained from normal male rats. However, in a mouse marrow culture model, they neither inhibited the parathyroid hormone (PTH)-induced calcium loss nor affected the formation of osteoclast-like cells induced by PTH in mouse marrow culture system. Therefore, our results suggest that both RJ and pRJ may prevent osteoporosis by enhancing intestinal calcium absorption, but not by directly antagonizing the action of PTH.

The effects of 26 metal ions, of which 23 are used in dental materials, on the conversion of amorphous calcium phosphate (ACP) to hydroxyapatite (HAP) in vitro were studied. From the effects on both the rate of HAP transformation and induction time, effects of metal ions were classified into three types; inhibitory (in the order: nickel, tin, cobalt, manganese, copper, zinc, gallium, thallium, molybdenum, cadmium, antimony, magnesium, and mercury); ineffective (cesium, titanium, chromium, iron [ferrous], iridium, palladium, platinum, silver, gold, aluminum, and lead); and stimulatory (iron [ferric] and indium). These results suggest that metal ions used in dental materials may modify the precipitation of oral calcium phosphate.

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The preventive effects of Fujiflavone P40 (a soybean isoflavone product) against both bone loss and periodontal alteration were evaluated using an ovariectomized rat model. Rats were divided into five groups: sham-operated (Sham), ovariectomized (OVX), OVX given Fujiflavone P40, OVX given 17beta-oestradiol, and OVX given the vehicle for 17beta-oestradiol, respectively. Fujiflavone P40 contains 46.6% isoflavones which consist of 24.1% daidzin, 16.5% glycitin and 5.9% genistin. Administration of Fujiflavone P40 to OVX rats suppressed the body weight gain until 5 weeks. Fujiflavone P40 also decreased total and high-density lipoprotein (HDL) cholesterols and triglyceride level of OVX rats, significantly. After 7 weeks, Fujiflavone P40 did not recover the coarsened fibre of the periodontal ligament. The ovariectomy decreased the uterine weight by 78%. The administration of 17beta -oestradiol recovered the weight loss by 99%, while Fujiflavone P40 restored it by 33%. The ovariectomy decreased the tibial bone mineral density (BMD) by 22%. The administration of 17beta-oestradiol to OVX rats recovered the tibial BMD decrease by 100%, while Fujiflavone P40 recovered it by 78%. The results suggest that Fujiflavone P40 may be useful as a preventive agent for osteoporosis.