Expression of vascular endothelial growth factor and hypoxia-inducible factor-1 alpha during the periovulatory period in goats

To evaluate the expression of vascular endothelial growth factor (VEGF) and hypoxia-inducible factor-1 alpha (HIF-1 alpha) during the periovulatory period, goat ovaries were collected at 0, 4, 8, 12, 24, and 48 h after treatment with 300 IU hCG. Total cellular RNA was isolated and VEGF and HIF-1 alpha were quantified using real-time RT-PCR. The mRNA levels of VEGF in thecal tissue remained unchanged prior to ovulation. However, the mRNA levels of VEGF in thecal tissues at 48 h increased to 7.5-fold of the level at 0 h (P < 0.05). In granulosa tissue, the VEGF mRNA levels were not detected in granulosa cells at 48 h. In thecal tissue, the mRNA level of HIF-1 1 alpha at 4 h was 1.5-fold of the level at 0 h and remained unchanged during 8-24 h; however the levels were significantly increased at 48 h. The mRNA levels of HIF-1a in granulosa at 4 h was not changed but levels were increased (P < 0.05) at 8 h and at 12 h and then decreased at 24 and 48 h, respectively. These data describe the relationships of VEGF-and HIF-1 alpha-dependent angiogenesis during the periovulatory periods by which hypoxia during ovulation is crucial for establishing the thecal new vasculature.