Ipriflavone modulates IGF-I but is unable to restore bone in rats.

Previously it has been reported that ipriflavone can prevent bone loss in ovarian hormone deficient rats. The present study evaluated whether ipriflavone was able to restore bone mass in osteopenic ovariectomized rats. Seventy-two, 90 day-old Sprague-Dawley rats were divided into six groups (sham two groups; ovariectomized four groups). Thirty-five days from the date of surgery, one sham and one ovx group were killed to verify the occurrence of bone loss. The remaining four groups were sham, ovx, ovx + ipriflavone (100 mg[sol ]kg body weight per day), or ovx + 17beta-estradiol (10 microg[sol ]kg body weight daily) for a period of 65 days. Ipriflavone was ineffective in restoring bone density and unlike estrogen did not prevent bone resorption as evidenced by increased (p < 0.05) urinary excretion of hydroxyproline and serum tartrate-resistant acid phosphatase activity. Ipriflavone increased (p < 0.05) the expression of IGF-I in the femur. These observations suggest that higher doses of ipriflavone or longer-term studies may be necessary to restore bone mass.