Effects Of Basic Fibroblast Growth Factor On The Bone Tissues Of Ovariectomized Rats

Objective:Postmenopausal osteoporosis and the associated increased incidence of bone fractures is a major health problem in elderly women.Treatment of osteoporotic patients with antiresorptive agents,such as estrogen and bisphosphonates, induces a modest increase in bone mass,but these agents do not seem capable of restoring lost bonecompletely to premenopausal levels,because of their inhibitory effect on bone formation as well as bone resorption.The purpose of this study was to investigate the effcet of basic fibroblast growth factor(bFGF) on the the bone tissues of ovariectomized(OVX) rats,to approach mechanism of action of bFGF on postmenopausal Osteoporosis.Methods:Osteoporosis models of rats were established by bilateral ovariectomy.Thirty female Sprague Dawley rats(3 months old) were divided into three groups(10 rats per group) at random:sham operation group,ovariectomized group and bFGF group.Bilateral ovariectomies were done on ovariectomized group and bFGF group.And then maintained untreated for 9 week post surgery.After 9 week,bFGF group was treated with bFGF(1mg/kg,five times per week);sham operation group and ovariectomized group were treated with Sodium Chloride.Three weeks later,bone mineral density was measured by dual energy-x-ray absorptiometry(DEXA),then all rats were sacrificed.The expression of IGF-I and TGF-β₁ in bone tissue was detected by immunohistochemical(stroptavidin- perosidase, S-P) technique and was quantitatively analysed.Results:1.the result of bone mineral density:Compared with sham operation group,the BMD of ovariectomized group decreased significantly(P＜0.01);Compared with ovariectomized group, the BMD of bFGF group increased significantly(P＜0.01); There was no significant difference between bFGF group and sham operation group(P＞0.05).2.The characteristics of HE staining in bone tissues:(1) Sham operation group:bone trabecula plentiful,arranged densely,and the interval among trabeculae was narrow.(2) Ovariectomized group:the trabecular became thinner and irregular compared with sham group,the interval among trabeculae was broaden.(3) bFGF group:bone trabecula plentiful,arranged densely,and the change is similar to Sham operation group.3.The expression and localization of IGF-I and TGF-β₁ in placental tissues:(1) The expression of IGF-I were localized in cytoplasim of osteoblasts,and less expressed in bone matrix. Compared with ovariectomized group,the expression of IGF-I in bFGF group was increased,and the difference has a statistical significance(P＜0.01).There was no significant difference between bFGF group and ovariectomized group(P＞0.05);(2) The color of immune positive products of TGF-β₁ was buffy and localized in cytoplasim of osteoblasts,and less expressed in osteocytes and bone matrix.Compared with ovariectomized group,the expression of TGF-β₁ in bFGF group was increased, the difference has a statistical significance(P＜0.01).There was no significant difference between bFGF group and ovariectomized group(P＞0.05).Conclusion:Basic fibroblast growth factor is a mitogen and has wide effects.It can increase the BMD,and improve the structure of trabecular.Basic fibroblast growth factor has a strong bone anabolic effect,maybe IGF-I and TGF-β₁ as potentialmediators for this effect.