Effects of soybean isoflavone dosage and exercise on the serum markers of bone metabolism in ovariectomized rats.

This study was designed to determine whether combined treatments with soybean isoflavone dosage and moderate exercise would exhibit synergistically effects on bone metabolism following the onset of menopause. Fifty 12 wk-old female Wistar rats were assigned to five groups: 1) Sham operated (Sham), 2) ovariectomized (OVX), 3) OVX received soybean isoflavone (OVX-IF), 4) OVX exercised (OVX-EXE) and 5) OVX treated with both soybean isoflavone and exercise (OVX-IF-EXE). All rats were fed a normal diet ad libitum. Daily soybean isoflavone dosage was 50 mg/kg body weight. The vehicle was given in Sham, OVX and OVX-EXE groups. The drugs were all oral administered using a stomach tube. Exercising rats were trained on an uphill treadmill at 20 m/min for 1h/day, 5 days/week. The experimental duration consisted of the adaptation periods of 2 weeks and treatment periods of 8 weeks. The results showed that the uterus relative weights in OVX-EXE, OVX-IF and OVX-IF-EXE groups were all lower than those in Sham, they were higher than those in the OVX group. Serum alkaline phosphates (AKP) activities of OVX was significantly increased as compared to that of Sham (p<0.01). OVX-IF and OVX-IF-EXE respectively decreased the Serum alkaline phosphates activities, as compared to that of OVX (p<0.01). The tartrate-resistant acid phosphatase (TRAP) value of OVX was significantly increased as compared to that of Sham (p<0.05). OVX-IF decreased the TRAP as compared to that of OVX (p<0.05). These results suggest soybean isoflavone and resistance exercise both can restrain ovx-induced bone loss. But their mechanisms may be different.