Resveratrol Prevents Rats From Glucocorticoid-induced Osteonecrosis Of The Femoral Head Via Activating SIRT1

Objectives:1. To investigate the effect of resveratrol on dexamethasone-induced apoptosis of osteoblast of rats in vitro and its probable mechanism2. To investigate the underlying mechanism of protective effects of resveratrol on glucocorticoid-induced osteonecrosis of the femoral head in rats.Methods:1. The skull of fetal rat was cut into pieces and digested by collagenase. Then the osteoblasts were harvested and cultured. P3cells were used to perform the follow-up experiments.10-6mol/L dexamethasone solution was used to induce the apoptosis of the apoptosis. The apoptosis index was tested by flow cytometry assay. The PCR and western blotting technique were applied to detect the expression of Sirtl and caspase-3.2.54male Wistar rats were equally divided into three groups randomly. Rats in the model control and resveratrol groups were developed into osteonecrosis by a sequential administration of lipopolysaccharide and methylprednisolone. In addition, rats in resveratrol group received a peritoneal injection of resveratrol (100mg/kg) for7days immediately after the first injection of lipopolysaccharide. The incidence of osteonecrosis, trabecular volume, apoptosis index, and protein expression of SIRT1and caspase-3in the femoral head were measured4weeks after the last methylprednisolone (or saline) injection.Results:1. The ALP test and the alizarin red staining showed positive results. FCM assay showed that cell apoptosis happened in the dexamethasone treated osteoblasts while resveratrol could inhibit such apoptosis induced by dexamethasone. And the apoptosis index in the Dexa group was higher than in the resveratrol group while the difference was significant (P<0.05). The apoptosis index was the lowest in the200μmol/L group. However, cell apoptosis scarcely detected in the blank control. The content of mRNA of sirtl in the resveratrol group which was higher than the dexamethasone group, and the difference was significantly. But the mRNA of caspase-3in the resveratrol group was lower than in the dexamethasone, and the difference was significant. The protein expression of sirtl in the resveratrol group which was higher than the dexamethasone group, and the difference was significantly. But the protein expression of caspase-3in the resveratrol group was lower than in the dexamethasone, and the difference was significant. 2. The incidence of osteonecrosis in the resveratrol group (46.67%) was significantly lower than that observed in the model control group (93.33%), while no osteonecrosis was observed in the blank control group. Compared with the model and blank control groups, the expression of SIRT1was much higher while the expression of caspase-3was much lower.Conclusions:1. Resveratrol exert anti-apoptotic effects in dexamethasone-induce osteoblast apoptosis of rats in vitro. Resveratrol may abolish the dexamethasone induced apoptosis of osteoblast by activating Sirtl and subsequently inhibiting the expression of caspase-3.2. Resveratrol administration can prevent glucocoticoid-induced osteonecrosis in rats, and the underlying mechanisms involve activating SIRT1and subsequently inhibiting caspase-3.