Influence of genistein on bone loss in orchidectomized rat model

We investigated the role of genisten on senile osteoporosis using orchidectomized (ORX) rats. Sixty seven‐week‐old male rats (n=10/group) were randomized to two groups: a sham‐operated group (SHAM) and an ORX group. The ORX group was subdivided into five groups: ORX control, ORX treated with genistein (G) 5, 10, 20 mg/kg or 17¥â‐estradiol (E2) 10 ug/kg of body weight per day by oral‐feeding. After four weeks, all rats were sacrificed. Body weight gain significantly decreased in ORX groups (97.67¡¾2.03 g) compared to in SHAM (114.70¡¾16.91 g). Serum alkaline phosphatase (ALP) activity increased in ORX control but decreased in G5, 10 and E2‐treated groups (49.6, 41.3 and 45.9% respectively). However, serum osteocalcin (OC) did not differ among the groups. G‐treated groups decreased in urinary deoxypyridinoline (Dpd) / Creatinine (Crea) ratio (70.73, 69.82 and 67.47% respectively). Expression of ALP mRNA in tibia was observed in G‐treated groups except ORX control. But there were no difference among the groups on expression of OC mRNA. These results suggest the possibility that genistein have protective effect on male bone loss by promotion of early bone formation and inhibition of bone resorption. (Supported by the Korea Research Foundation Grant funded by the Korean Government Grant# KRF‐2004‐F00003)