Expression of hypoxia-inducible factor-1α during ovarian follicular growth and development in Sprague-Dawley rats

Hypoxia-inducible factor-1 alpha (HIF-1 alpha) has been identified as a transcription factor that is involved in diverse physiological and pathological processes in the ovary. In this study, we examined whether HIF-1 alpha is expressed in a cell-and stage-specific manner during follicular growth and development in the mammalian ovaries. Using immunohistochemistry and Western blot analysis, HIF-1 alpha expression was observed in granulosa cells specifically and was significantly increased during the follicular growth and development of postnatal rats. Furthermore, pregnant mare serum gonadotropin also induced HIF-1 alpha expression in granulosa cells and ovaries during the follicular development of immature rats primed with gonadotropin. Moreover, we also examined proliferation cell nuclear antigen, a cell proliferation marker, during follicular growth and development and found that its expression pattern was similar to that of HIF-1 alpha protein. Granulosa cell culture experiments revealed that proliferation cell nuclear antigen expression may be regulated by HIF-1 alpha. These results indicated that HIF-1 alpha plays an important role in the follicular growth and development of these 2 rat models. The HIF-1 alpha-mediated signaling pathway may be an important mechanism regulating follicular growth and development in mammalian ovaries in vivo.