Rutin inhibits ovariectomy-induced osteopenia in rats

Several studies suggest that polyphenols might exert a protective effect ag ainst osteopenia. The present experiment was conducted to observe the effec ts of rutin (quercetin-3-O-glucose rhamnose) on bone metabolism in ovariect omized (OVX) rats. Thirty 3-month-old Wistar rats were used. Twenty were OV X while the 10 controls were sham-operated (SH). Among the 20 OVX, for 90 d ays after surgery 10 were fed the same synthetic diet as the SH or OVX ones , but 0. 25% rutin (OVX + R) was added. At necropsy, the decrease in uterin e weight was not different in OVX and OVX + R rats. Ovariectomy also induce d a significant decrease in both total and distal metaphyseal femoral miner al density, which was prevented by rutin consumption. Moreover, femoral fai lure load, which was not different in OVX and SH rats, was even higher in O VX + R rats than in OVX or SH rats. In the same way, on day 90, both urinar y deoxypyridinoline (DPD) excretion (a marker for bone resorption) and calc iuria were higher in OVX rats than in OVX + R or SH rats. Simultaneously, p lasma osteocalcin (OC) concentration (a marker for osteoblastic activity) w as higher in OVX + R rats than in SH rats. High-performance liquid chromato graphy (HPLC) profiles of plasma samples from OVX + R rats revealed that me an plasma concentration of active metabolites (quercetin and isorhamnetin) from rutin was 9.46 + 1 muM, whereas it was undetectable in SH and OVX rats . These results indicate that rutin (and/or its metabolites), which appeare d devoid of any uterotophic activity, inhibits ovariectomy-induced trabecul ar bone loss in rats, both by slowing down resorption and increasing osteob lastic activity.