Objective： To explore the pathogenesis mechanism of osteoporosis due to menopause after ovaries removal, and study the action mechanism of Zuogui Pill by studying the expression of Notch1 and BMP9 in thighbone of osteoporosis rats due to menopause after ovaries removal. Methods： The osteoporosis rat models were established by removing bilateral ovaries of femal rats. Rats in experiment group were treated with Zuogui Pill for 12 weeks. Rats in positive group were treated with Fosamax. Rats in normal control group, sham operation group and model group were not treated. The expression of Notch1 and BMP9 proteins were tested by using ELISA method. Results： The results of ELISA showed that the expression of Notch1 and BMP9 in thighbone of rats in model group was significantly lower than that of normal control group. After treating with Fosamax and Zuogui Pill for 12 weeks, Zuogui Pill could increase the expression of Notch1 and BMP9 in thighbone of rats（P0.01）. Conclusion： The decrease in expression of Notch1 and BMP9 proteins might be one of the mechanism of osteoporosis. Zuogui Pill could increase the expression of Notch1 and BMP9 proteins, which showed some prevention and curative effects on osteoporosis.
China Journal of Traditional Chinese Medicine and Pharmacy