Abstract:

Objective  To explore the correlation between ATF4 and GPR48 expressions, which might reflect the correlative regulation effects during the progression of traumatic necrosis of the femoral head in rats. Methods  A total of 36 SD rats were divided into two groups: the experimental group (n=24) which were models of traumatic necrosis of the femoral heads operated with Norman′s technique, and the control group (n=12) which received sham operation. The femoral heads were collected 1w, 2w and 4w after operation, and then analyzed with histological and immunohistochemical Methods  , RT-PCR and Western blotting to observe the progression of necrosis.  Results  From the 1st to 4th week, the necrosis gradually aggravated. In the 4th week, there were breakages on the articular cartilage with rough surface. Immunohistochemical analysis showed that the expressions of ATF4, GPR48 and PCNA in the experimental group gradually increased, but were significantly lower than those in the sham operation group (P<0.05) at the same time point. RT-PCR Results   suggested that mRNA of ATF4 and GPR48 gradually increased with time going. Western blotting displayed that the protein expressions of ATF4 and GPR48 gradually elevated in the experimental group, and ATF4 had a positive correlation with GPR48 (r=0.659, P<0.01). Conclusion  In the progression of traumatic necrosis ofthe femoral head, the expressions of ATF4 and GPR48 decline in the initial stage but may gradually increase. There is a positive correlation between them, which might be associated with the concomitant repair of the necrotic bone.

Key words: Osteonecrosis of the femoral head, Rats, Activating transcriptional factor 4, G-protein coupled receptor 48, Trauma