| ObjectiveTo detect the expressions of Caspase-3, Adipoq, β-catenin, LRP5 and BMP-2 m RNA in the tissue of avascular necrosis femoral head of steroid-induced juvenile rabbit model, as well as to explore the relationship between the Wnt/ β-catenin signal pathway and juvenile rabbit steroid-induced avascular necrosis of femoral head.MethodsThirty-five healthy New Zealand rabbits with 8-week-old age were selected, weighing 1.1 to 1.9kg. They were randomly divided into two groups: the steroid injection group(SIG)(n=25) and the control group(CG)(n=10). Prednisolone acetate of 7.5 mg/kg was injected into each rabbit for the SIG and equal volume saline for the CG twice a week for eight weeks. X-ray and CT examination were performed at the 4th and 8th week after the first injection. All experimental animals were sacrificed after the 8th week, their bilateral femoral head were collected. A part of them for RT-PCR examination was stored in-80 degrees refrigerator. Another was made of wax stone used for histopathological examination. According to imaging and histopathology results, the SIG was further divided into the disease group(DG) and the non-disease group(NDG). The RT-PCR method was used to detect the expressions of Caspase-3, Adipoq, β-catenin, LRP5 and BMP-2 m RNA in the femoral heads of DG, NDG, CG and compare the differences among the three groups.Results1. In SIG(n=25), only 22 rabbits survived in the end, 6 experimental animals were identified having positive avascular necrosis, the incidence was 27.3%(6/22).2.In the DG, the osteoporosis of the femoral head was extensive, cystic photic zone appeared and the edges cystic photic zone become blur; the surface becomes slightly flat, with varying degrees of collapse; trabecular bone boundaries disorder and become blur with some interruption and necrosis; the hip clearance was narrower than in the CG.3. The bone trabeculae were breaked and became sparser, partial of them were deleted in SIG. the number of bone cells reduced;more fat cells can be seen; the arrangement of the epiphyseal plate cells were irregular;nuclear was missing obviouly in the cells.4. The expression levels of β-catenin in DG, NDG and CG were(0.22±0.01),(0.35±0.09) and(1.07±0.41). Significant differences was found between CG and another two groups(t=4.94,10.60, P<0.05). The expression levels of LRP5 in DG, NDG and CG were(0.22±0.05),(0.35±0.12),(1.12±0.36). The differences between CG and another two groups was significant(t=4.39, 9.93, P<0.05). The expression levels of Adipoq in DG, NDG and CG were(17.84±5.51),(3.33±1.26) and(1.11±0.27). Significant differences was found between CG and another two groups(t=5.88, 12.01, P<0.05). The expression levels of Caspase-3 in DG, NDG and CG were(3.10±0.90),(1.29±0.35),(1.06±0.24).The differences between CG and another two groups was significant(t=7.15, 7.75, P<0.05). The expression levels of BMP-2 in DG, NDG and CG were(0.08±0.05),(0.31±0.21),(1.12±0.32). The differences between CG and another two groups was significant(t=2.93, 8.08, P<0.05).In DG, NDG and CG, the expression levels of β-catenin with LRP5 were positively correlated(r=0.779,0.914,0.885,P=0.008,0.020,0.019); the expression levels of Caspase-3 with β-catenin were negatively correlated(r=-0.782,-0.839,-0.838, P=0.008,0.022,0.026); the expression levels of Caspase-3 with LRP5 were negatively correlated(r=-0.782,-0.839-0.838, P=0.008,0.022,0.026);the expression levels of Adipoq with β-catenin were negatively correlated(r=-0.733,-0.702,-0.736, P=0.016, 0.006, 0.036); the expression levels of Adipoq with LRP5 were negatively correlated(r=-0.749,-0.607,-0.756,P=0.013,0.023, 0.043);the expression levels of BMP-2 with β-catenin were positively correlated(r=0.708,0.622,0.844,P=0.022,0.010,0.035); the expression levels of BMP-2 with LRP5 were positively correlated(r= 0.521, 0.701, 0.777, P=0.023,0.021,0.022).Conclusion1. Wnt/β-catenin signal pathway was inhibited in the steroid-induced juvenile rabbit model of avascular necrosis of femoral head.2. Inhibitory effects of glucocorticoids on Wnt/β-catenin signal pathway might contribute to the apoptosis of osteoblasts and chondrocytes of the femoral head, promoting the formation of fat cells and inhibiting their osteogenic ability. |
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