Saburo Hidaka

Royal Jelly Prevents Osteoporosis in Rats: Beneficial Effects in Ovariectomy Model and in Bone Tissue Culture Model

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.

A Japanese herbal medicine, Chujo‐to, has a beneficial effect on osteoporosis in rats

The inhibitory effects of a Japanese herbal medicine, Chujo‐to, on the progress of bone loss induced by ovariectomy in rats were investigated. Ovariectomized rats were administered with Chujo‐to during weeks 7–14 after ovariectomy. At 14 weeks, the bone mineral density of the tibia from ovariectomized (OVX) rats had decreased by 27% compared with those in the sham‐operated rats, and by a 18%–21% and 16% decrease after the administration of Chujo‐to and 17β‐oestradiol, respectively. The surface of a trabecular bone of the tibia in ovariectomized rats had a porous and fibrous appearance, while that of the same bone in sham‐operated rats was composed of fine particles. After the administration of Chujo‐to or 17β‒oestradiol, the surface of trabecular bone maintained the porous and fibrous appearance. The uterine weight was not restored by Chujo‐to but by 17β‐oestradiol. These results suggest that Chujo‐to has an efficacy on the osteoporosis of rats similar to 17β‐oestradiol, but with a different mechanism. Copyright

Thermal analysis of bones from ovariectomized rats

Thermal analyses [thermogravimetry (TG) and differential thermal analysis (DTA)], X-ray diffraction, and infrared absorption analysis of bones from ovariectomized rats were carried out. The rats were divided into five groups: sham operated (Sham); ovariectomized (OVX); OVX given traditional Chinese (Kampo) medicine, Unkei-to; OVX given 17 beta-estradiol; and OVX given the estradiol vehicle, respectively. The activation energy (delta E), a kinetic parameter from TG data of OVX rats, increased by 57% from that in Sham rats. The administration of Unkei-to and 17 beta-estradiol to OVX rats clearly restored the delta E to the levels of Sham rats, while the vehicle for 17 beta-estradiol had no effect. DTA data from thermal analyses of rats from the Sham, OVX, and OVX given various compounds were almost the same except for OVX rats given 17 beta-estradiol. The X-ray diffraction pattern and infrared absorption spectrum of bone powders from Sham rats were not different from those of OVX rats or others. These results strongly suggest that kinetic parameter, delta E calculated from TG data, may be a useful method for assessing both experimentally induced osteoporosis and drug effects on it.