The Study Of EGCG On Bone Loss In Rat Maxillary

[Objective]To investigate the preventive and therapeutic effects of(-)-epigallocatechin-3-gallate(EGCG)on osteoporotic bone loss in upper jaw bone induced by ovarian castration in Sprague-Dawley(SD)rats and periodontitis induced by ligation and inoculation with Porphyromonas gingivalis in SD rats.[Methods]Experimental rat model of postmenopausal osteoporosis and animal model of periodontitis were established by ovariectomy and wire ligation combined with inoculation of Porphyromonas gingivalis.The therapeutic effect and its mechanisms of early EGCG intervention on bone loss of upper jaw bone caused by postmenopausal osteoporosis and periodontitis were explored.Forty-eight female SD rats were randomly divided into six groups:the group A was sham-ovariectomized rats(SHAM),group B was bilateral ovariectomy + saline rats(OVX),group C was EGCG-ovariectomized rats(OVX + EGCG),group D was sham-ligation rats(SHAM),group E was ligation + saline rats(Ligation,Ligation)and group F was ligation +EGCG rats(EGCG-Ligation,Ligation+EGCG).There were 8 rats in each group.The intervention was started three days after the operation,and EGCG or saline was given by gavage at a dose of 10 10mg·(kg·d)-1,six days a week.After 12 weeks of administration,the rats were sacrificed.The preventive and therapeutic effects and potential mechanisms of the EGCG on rat osteoporotic bone loss in upper jaw bone induced by ovariectomy and ligation-induced rat periodontitis were explored by analysis of body weight change,micro-CT scan analysis of bone mineral density and bone morphological parameters,HE staining comparative analysis of morphological changes of rat jaws,ELISA and immunohistochemical analysis of OPG and RANKL expression levels in rat serum and maxilla.[Results]After micro-CT scan analysis,HE staining morphological analysis,ELISA analysis and immunohistochemical analysis,the parameters in the ovariectomized model group and the ligation induction model group were all significant changed in comparison of those in the negative control group.The OPG levels in serum and maxilla were significantly reduced,RANKL levels were increased,while the overall bone mineral density value decreased significantly,the number of maxillary bone trabecula was decreased and the degree of trabecular separation was increased,indicating that the two methods for establishing models were practical and reliable.After 3 months of EGCG administration,there was no significant change in body weight in the ovariectomized and ligation-induced periodontitis model rats compared with the EGCG group.It was shown that EGCG had certain preventive and therapeutic effects on osteoporotic bone loss of upper jaw bone induced by ovariectomy and ligation-induced periodontitis without affecting the body weight and health of the rats.Compared with the ovariectomized model group and the ligation-induced model group,the increase of the bone density of the maxilla and the degree of trabecular separation were significantly inhibited in the rats of EGCG treatment group;it also had inhibitory effect on the decrease of the number and thickness of bone trabecula in the maxilla but it did not reach significance(P>0.05);EGCG also played a certain role in improving the morphological changes of jaw bone;the most significant was that EGCG significantly promoted the expression of OPG(P<0.01,P<0.05),significantly inhibited the expression of RANKL(P<0.05,P<0.05)in serum and maxilla of rats.The OPG/RANKL ratio also had significant changes(P<0.05,P<0.05),It was indicated that EGCG treatment changed the processes of bone formation in the rats with osteoporosis and periodontitis,inhibited the bone resorption and promoted bone formation in the affected rats.[Conclusions]The methods of ovariectomy and wire ligation combined with inoculation of Porphyromonas gingivalis were stable and reliable for establishing the experimental rat model of postmenopausal osteoporosis and animal model of periodontitis.The EGCG had significant preventive and therapeutic effects on the osteoporotic bone loss of rats and ligation-induced periodontitis,which provides reliable theoretical basis for the clinical simultaneous treatment of osteoporosis and periodontitis.