The Effect Of Resveratrol On Preventing Steroid-Associated Osteonecrosis In Rabbits

Background:Steroid-associated osteonecrosis (ON) is an intractable and disabling disease in orthopedics. Anticoagulant,lipid-lowering agent,ossification agent,and fibrinolytic agent may exert some indefinite effect on ON and have many complications.Drug treatment for ON can only delay the progess of the disease,but not reverse it,so it is more efficient to prevent the development of ON. The etiopathogenesis of steroid-associated ON is not very clear,but intravascular thrombosis and extravascular lipid-deposit-induced compression are the two generally accepted mechanism. Resveratrol,one kind of polyphenol, has the potential of anti-oxidation,regulation of lipid metabolism,protection of vascular endothelium cell,modification of inflammatory factor and inhibition of platelet aggregation and secretion. We will establish a steroid-associated ON model in rabbits and evaluate the effect of resveratrol on preventing steroid-associated ON development in rabbits.Methods:Seventy-two New-Zealand white rabbits were randomly divided into four grous.30 rabbits were included in resveratrol preventing group (Pro) and intravenously injected with 10μg/kg body weight of Lippolysaccharide (LPS) on day 0 (week 0),following with three times intravenous injections of 20 mg/kg body weight of Methylprednisolone (MPS) at a time interval of 24 h. Intraperitoneal injection of 4 mg/kg body weight of resveratrol was given on day 0 and lasted for two weeks at a time interval of 24 h.30 rabbits were involved in Osteonecrosis group(AVN) and intravenous injected with LPS and MPS as that in Pro group.but intraperitoneal injected 2 weeks with diluted alcohol.6 rabbits of resveratrol control group (Res) were intravenous injected four times with physiological saline and intraperitoneal injected two weeks with 4 mg/kg body weight of resveratrol.6 rabbits of control group were intravenous injected four times with physiological saline and intraperitoneal injected 2 weeks with diluted alcohol.36 rabbits were separately killed week 2 and month 3 after the last MPS injection,and bilateral femoral and humeral samples were harvested. Plasma t-PA (Tissue-type plasminogen activator), PAI-I (plasminogen activator inhibitor type I), TM(thrombomodulin) and VEGF(Vascular endothelial growth factor) were detected by ELISA(Enzyme-linked immunosorbent assay). Dynamic contrast-enhanced MRI was perfomed for local intraosseous perfusion. The incidence of osteonecrosis was assessed by HE staining and local TF and VEGF expression were graded by immunohistochemistry.Results:The ON incidence was 80.0%in AVN group and 43.8%in Pro group at week 2,and the difference is significant (P=0.043).The ON incidence was 50%and 36.4%respectively at month 3 and without significant difference.There were no ON in the Res group and Con group.TM and VEGF concentration were significant higher in the AVN group than that in Pro group at week 1, week 2 and week 4,but there was no significance at month 3.The level of t-PA and PAI-1 showed a wavy change in both AVN and Pro group,and no significant difference occurred between the two groups.ME in the AVN group decreased significantly at week 1 postinduction (P<0.05), then significantly increased over baseline at week 2 and decreased at month 3.The variance of ME in the Pro gourp is not significant. Moderate (++) and strong immunoreactivity (+++) of local TF and VEGF expression were found in AVN group and weak (+)and moderate (++) immunoreactivity were found in Pro group.Conclusions:Single intravenous injection of low dose LPS,combined with three intravenous injection of high dose MPS can successfully establish steroid-associated ON in rabbits. Dynamic contrast-enhanced MRI can reflect the perfusion of femoral head,consist with the pathological features and it is a reliable method to predict the ON development at early stage. Resveratrol can reduce the ON incidence by different mechanisms.