Effects of different-term treatment of alendronate on osteoporosis induced by ovariectomized in rats

AIM To investigate the effects of different period of Alendronate in ovariectomized (OVX) rats. METHODS Forty Three 3 month old Sprague Dawley female rats were randomly devided into six groups: sham operated (Sham group 30 d and group 90 d), ovariectomized controls(OVX group 30 d and group 90 d), ovariectomized+alendronate 1 mg·kg -1 ·d -1 (group 30 d and group 90 d). Double in vivo fluorochrome labeling was made. At the end of experiment, the left tibiae were havested for histomorphometrical evaluations. RESULTS Ovariectomized rats trabecular bone mass were reduced markedly because bone resorption excessed bone formation(% Tb.Ar -25% 30 d and -62% 90 d). Treatment with alendronate increased bone volume by 45% in 30 d and by 219% in 90 d and suppressed bone turnover rate by 25% in 30 d and by 62% in 90 d. CONCLUSIONS Treatment with alendronate for 30 d and 90 d can prevent osteoporosis induced by inhibiting bone resorption and bone turnover. The treatment of 90 d was more potent than that of 30 d in protecting agsinst osteoporosis in ovariectomized rats via supression of bone turnover.