| Objective:To research the pathogenesis of steroid-induced avascular necrosis of the rabbit femoral head(SANFH),observe the effect of shRNA adenovirus vector targeting PPAR? gene on PPAR?m RNA transcription and protein expression in rabbit femoral head,and evaluate the preventive effects of shRNA targeting PPAR? gene on SANFH in rabbit model.Finally,to provide a novel approach to the prevention of steroid-induced osteonecrosis.Methods:Forty-eight healthy New Zealand rabbits were randomly into four groups:Group M treated with dexamethasone only;Group S with dexamethasone and a recombinant adenovirus shuttle vector carrying shRNA targeting PPAR? gene;Group E with dexamethasone and a vector carrying irrelative sequence;Group N with Saline serving as control.Detection of serum triglycerides(TG)and cholesterol(CHO)levels.Histopathological staining was preformed to evaluate osteonecrosis.The expression levels of PPAR? m RNA and Runx2 m RNA were analyzed by Q-PCR.Immunohistochemistry was performed to detect the PPAR? and Runx2 protein expression.The statistical software SPSS13.0 was used to analyze the data,difference was statistically significant(P < 0.05)Results:1.Serum test results:On the 4th and 8th week,The levels of serum TG and CHO in group M?E and S increased gradually with the experimental progress,and significantly higher than group N,and the difference was statistically significant(P <0.05).2.Histological examination results:On the 8th week,the general shape of femoral head observation,the appearance of femoral head specimens was normal in group N and group S,the articular cartilage was smooth and clean,and showed healthy colour;The articular cartilage smoothness was poor in group M and group E,and the right side of the femoral head quadrant surface become darker,showed a little cartilage exfoliation,the visible ecchymosis scattered below the cartilage.HE staining results:there was not obvious osteonecrosis in group N and group S,the structure of subchondral bone lacuna was complete and arranged neatly,the bone cells in bone lacuna were clearly visible.There was obvious osteonecrosis in group M and group E,bone lacuna become fine and sparse,partially broken into pieces,subchondral bone plate thinning,the bone lacuna contained a large number of empty lacuna.3.Q-PCR results:On the 4th week,The expression of PPAR? m RNA in the femoral head of group S was lower than group M and group E(P<0.05).The expression of Runx2 m RNA was higher than group M and group E(P<0.05).Compared with group S and group N,group E and group M,the difference was not statistically significant(P>0.05).On the 8th week,The expression of PPAR? m RNA in the femoral head of group S was significantly lower than group M and group E(P<0.05).The expression of Runx2 m RNA was significantly higher than group M and group E(P<0.05).Compared with group S and group N,group E and group M,the difference was not statistically significant(P>0.05).4.immunohistochemical results:On the 8th week,the expression of PPAR? protein in group S was low,the expression of Runx2 protein in group S was high,compared with group M and group E,the difference was statistically significant(P < 0.05),compared with group N,the difference was not statistically significant(P>0.05).Conclusion:1.The SANFH model of rabbit was successfully constructed;2.Long-term and high-dose glucocorticoids intake,the adipocyte in rabbit head would be proliferation and hypertrophy,and empty osteocyte lacunae increasing,which induces steroid-induced femoral head necrosis;3.shRNA adenovirus vector targeting on PPAR? gene can effectively block the expression of PPAR? m RNA in the rabbit femoral head,inhibit adipogenic differentiation of BMSCs;Enhance the expression of Runx2 m RNA,promote osteogenic differentiation;4.shRNA adenovirus vector targeting on PPAR? gene can prevent the occurrence of SANFH,which provides a novel approach to the prevention of steroid-induced osteonecrosis. |
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