Effects Of Estrogen On The Expression Of TGF-β In Early Fracture Healing Of Ovariectomized Rats

Objective To study the effects of Progynova on osteoporosis association with femoral fracture in ovariectomized rats and to explore the possible mechanism of estrogen by the influnce on the expression of TGF-β. To provide the possibility of treatment for postmenopausal osteoporotic fracture.Method fifty-four Sprague-Dawley(SD) female rats, aged6-month-old,were divided into three groups randomly: SHAM group, OVX group, and Progynova group .The osteoporotic model was established by ovariectomy except SHAM group. The right femur was broken by operation at 8 weeks later. Progynova tablets were given through gastromy, 0.104mg/kg /d, immediately after operation .The rats in three groups were killed at the end of 2, 4, 6, 8 weeks postoperatively respectively for study. The study index include: the bone of X-rays; the histological of bone calluses (HE dye), the index of osteoblasts and osteoclasts ; the immunohistochemical SABC and gray scales scan quantity analysis for TGF-β in bone calluses.Results 1. The density of calluse of OVX group was lowest in three groups, and the line of fracture was still exist in OVX group while it were unclear or disappeared in other two groups at time. 2. There was more number of osteoclasts in OVX group than in other two groups and there was no obvious differences of number of osteoblasts in the three groups on the surface of osseous trabecula. Original trabecular bone changed slowly into mature trabecular bone , part of which had been absorbed and disappeared at 8th week in OVX group. In other two groups, trabecules became thicker and denser gradually. 3.osteoblast index and osteoclast index: at 2nd ,4th weeks, OCI of OVX group is higher than that of other two group. There is no difference for OBI in three groups. 4. expression of TGF-β: OVX group: at 2nd, 4th weeks, the positive expression of TGF-β was in chondrocyte, fibroblast and matrix, only in 6th, 8th weeks the osteoblast showed positive expression. Progynova group: at 2nd week, TGF-β expressd notably in chondrocytes, at 4th weeks osteoblasts were positive expression whereas the hypertrophy chondrocytes were almost negative . SHAM group: to be familiar with Progynova group. 4. gray scales scan quantity analysis: TGF-β in bone calluses of three groups hited the top and descended gradually, obviously 4 weeks later. TGF-β of OVX group was always lower than that of other groups in second and further weeks .Conclusion Progynova makes osteoclast decreased and osteoblast increased , inhibits bone absorption, stimulates bone formation, reduces bone tuneover, promote chondralscab's transfer to ostealscab. It shows that estrogen is good for fracture healing of postmenopausal osteoporosis. TGF-β was strongerly expressed in SHAM group and Progynova group thanin OVX group, mainly expressing in chondrocytes and osteoblasts during active functional stage and in matrix. It is presumed that TGF-β enhance cartilage forming and bone forming , inhibit bone absorption, TGF-β acts as an important role in early stage of bone fracture healing. The possible mechanism of estrogen on promoting osteoporotic fracture healing is that estrogen enhance the expression of TGF-β in callus.