Combination of norethisterone with ethinylestradiol showed synergetic effect on ovariectomy induced osteopeniain rats / 中国药理学通报

ABSTRACT

AIM To determine whether norethisterone in combination with ethinylestradiol can completely prevent bone loss in ovariectomized rats. METHODS Twenty-four Sprague-Dawley female rats at the age of 4.5 months were sham-operated and treated orally with vehicle, or ovariectomized (OVX) and treated orally with either vehicle or combined norethisterone (norethisterone at 60 ?g?kg -1?d -1 and ethinylestradiol at 3.5 ?g?kg -1?d -1) for 90 days. Double in vivo fluorochrome labeling was administrated. The undecalcified longitudinal proximal tibial metaphyseal sections were used for the bone histomorphometric analysis. The humerus and urine calcium contents were assayed by the method of atomic absorption spectrometry. The humerus and urine hydroxyproline contents were assayed by colorimetry. Blood serum alkaline phosphatase (ALP) were tested by BECKMAN auto bio-chemistry analyzer. RESULTS After 90 days post OVX the cancellous bone mass and showed high bone turnover indices. Bone hydroxyproline contents were lost markedly. The ALP activity increased. The urine hydroxyproline contents increased significantly. The combined norethisterone treated group prevented bone lost when compared with OVX. The combined norethisterone were shown to inhibit osteoclasts surface and decrese bone turnover rate. The combined norethisterone can increase hydroxyproline contents and reduce urine hydroxyproline contents significantly from OVX group. CONCLUSION Combining norethisterone can prevent OVX-induced cancellous bone loss in rats.