Influence Of Estrogen And Progesteron On Bone Histomorphometry And VDR MRNA Expression In Ovariectomized Rats

Objective:l.To study the effects of Estrogen and Progesteron on bone histomorphometry in Ovariectomized Rats.2.To study the influence of Estrogen and Progesteron on VDRmRNA expression in the kidney of Ovariectomized Rats. Methods:1.Forty three femal Sprague-Dawley rats,three months old,were divided randomly into 5 groups:sham-operated (sham,5),Ovariectomized group (OVX,10),Ovariectomized and received with Estrogen(OVX+E,ll),Ovariectomized and received with Progesteron(OVX-HP,8),Ovariectomized and received with Estrogen and Progesteron (OVX+E+P,9). After three and half months,all animals were killed. Static and dynamic parameters of right tibias were evaluated.2.When the rats were sacrificed,the renal were collected instantly. After washed with ice saline,total RNA was extracted. The expression of VDRmRNA was assessed by RT-PCR. Results:1 .The bone mass of cancellous bone decreased significantly in OVX Group with bone structure weaken and the parameters of formation and resorption increased.( compared with Sham,P<0.05).2.The bone mass of cancellous bone increased significantly in OVX+E Group and OVX+E+P Group. The parameters of bone formation and resorption decreased .(compared with OVX,P<0.05). 3.Compared with OVX Group,the parameters of bone mass,bone formation and resorption in Group OVX+P shown no difference. 4.RT-PCR revealed marked decrease in band intensity corresponding with theVDRmRNA product in Group OVX ( compared with Sham,P<0.05).5.The expression of VDRmRNA in the renal of Group 'OVX+E' and' OVX+E+P' increased markedly (compared with OVX,P<0.05). 6.The expression of VDRmRNA in the renal of Group 'OVX+P' shown no static increase (compared with OVX).Conclusion:l.Bone formation and resorption increased significantly in Group 'OVX' which indicates bone loss rapidly.l.Estrogen prevents bone loss effectively by inhibiting bone resorption and bone formation,leading to decrease of bone turnover in Ovariectomized rats. S.Progesteron has no effect on high bone turnover and the protection of Estrogen in Ovariectomized rats.4.The expression of VDRmRNA decreased significantly in the renal of Ovariectomized rats.5.Estrogen increased the expression of VDRmRNA in the renal of Ovariectomized rats.6.Progesteron has no effect on the expression of VDRmRNA in the renal of Ovariectomized rats.