Expression of hypoxia inducing factor-1α in rats' ovary under tail-suspension weightlessness / 解放军医学杂志

ABSTRACT

Objective To investigate the expression feature of hypoxia inducing factor-1α (HIF-1α) in rats' ovary under simulated weightlessness. Methods Sixty adult female Wistar rats, weight 200±20g, were randomly divided into 10 groups (6 each) a control group without simulating weightlessness, and experimental groups underwent tail suspension for 0.25, 0.5, 1, 2, 3, 5, 7, 14 and 21-day, respectively. The HIF-1α expression in rats' ovaries was assessed by immunohistochemical staining and RT-PCR assay. Results Positively stained HIF-1α was observed as brown particle in follicular oocytes, granulosa cells and thecal cells of rat ovaries in both experimental and control groups. The positively stained HIF-1α granules mainly located in the cytoplasm of ovarian cells in control group, while in tail-suspension 0.25-day and 0.5-day groups, the granules transferred from cytoplasm to nucleus of follicular oocytes, granulosa cells and thecal cells. The expression level in tail-suspension 1-day group was similar to that in control group, and the staining of nuclei disappeared. The expression level of HIF-1α mRNA was significantly higher in tail-suspension 0.25-day and 0.5-day groups than that in control group (P<0.05). One day after tail-suspension, the expression levels of both HIF-1α protein and HIF-1α mRNA gradually recovered to that of control group. Conclusion The simulated weightlessness by tail-suspension, serving as a kind of stress, may increase the expression of both HIF-1α protein and HIF-1α mRNA in rat ovary during the early period, implying that a close correlation between the HIF-1α expression in rats' ovary and the weightlessness stress tolerance.