Abstract:

BACKGROUND: Animal experiments show that hormone can induce femoral capillaries poor filling, decrease capillaries density in unit area, and reduce capillaries in cancellous bone inferior to cartilage. However, the involved mechanism remains unclear.
OBJECTIVE: To explore the changes of vascular endothelial growth factor (VEGF) during the progress of glucocorticoid induced osteonecrosis.
METHODS: The Chinese white rabbits were randomly divided into horse serum plus prednisone group and prednisone alone group. Typical osteonecrosis model was established by Matsui Method. 10 mL/kg horse serum was injected into horse serum plus prednisone group through the ear margin veins, followed by additional injection after 2 weeks and intraperitoneal injection of prednisone, 45 mg/kg per day for 5 consecutive days. The control group was only subjected to prednisone, 45 mg/kg per day for 5 consecutive days. The VEGF expression was observed by means of reverse transcription polymerase chain reaction (RT-PCR) before, 7, 14 days after administration, 1, 3, 7, 21, 35 and 49 days following the first application of hormone. The capillaries were quantified.
RESULTS AND CONCLUSION: The VEGF was significantly increased 7 days following horse serum, and gradually decreased to levels before treatment 1 days following hormone. The VEGF mRNA expression decreased with increasing hormone treatment, in particular at  7 and 21 days (P < 0.05), but cannot restore to normal level. Microvascular count was decreased gradually, and at 21 days decreased to the minimum, positively correlated with VEGF expression. Results show that adrenal glucocorticoid inhibited VEGF expression in bone tissue and restrained angiogenesis, resulting in ischemia and hypoxia of the local environment in bone tissue. VEGF expression highly correlates with microvascular count and osteonecrosis degree.