The effects of reduced oxygen tension on swine granulosa cell.
Follicular growth is characterized by an augmented vascularization, possibly driven by a fall in the oxygen supply. The present study was undertaken to investigate the effects of hypoxia on swine granulosa cells. At first, we quantified oxygen partial pressure (pO2) in follicular fluid from different size follicles; the granulosa cells collected from large follicles (>5 mm) were subjected for 18 h to normoxia (19% O2), partial (5% O2) or total hypoxia (1% O2). The effects of these conditions were tested on the main parameters of granulosa cell function, steroidogenesis and cell proliferation, and on vascular endothelial growth factor (VEGF), nitric oxide (NO) and superoxide anion (O2-) production. Oxygen tension in follicular fluid was negatively related to follicular size, pointing out a gradual reduction during follicular growth. Severe hypoxic conditions determined a reduction of both 17beta estradiol and progesterone production, while partial hypoxia did not seem to affect them. Hypoxia increased VEGF as well as O2- production in swine granulosa cells without impairing cell growth; in addition, it decreased NO output. We may conclude that physiological hypoxia could play a pivotal role in the follicular angiogenic process stimulating VEGF synthesis by granulosa cells. ROS are possibly involved in hypoxic signalling.
Basini
Giuseppina
G
Dipartimento di Produzioni Animali, Biotecnologie Veterinarie, Qualità e Sicurezza degli Alimenti-Sezione di Fisiologia Veterinaria, Università di Parma, Via del Taglio 8, 43100, Italy. basini@unipr.it
Bianco
Federico
F
Grasselli
Francesca
F
Tirelli
Martina
M
Bussolati
Simona
S
Tamanini
Carlo
C
D000818:Animals; D049109:Cell Proliferation; D004958:Estradiol / Q000378:metabolism; D005260:Female; D006107:Granulosa Cells / Q000378:metabolism*; D000860:Hypoxia; D009569:Nitric Oxide / Q000378:metabolism; D006080:Ovarian Follicle / Q000378:metabolism*; D010100:Oxygen / Q000378:metabolism*; D011374:Progesterone / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D013552:Swine; D042461:Vascular Endothelial Growth Factor A / Q000378:metabolism
D042461:Vascular Endothelial Growth Factor A; D013481:Superoxides; D009569:Nitric Oxide; D011374:Progesterone; D004958:Estradiol; D010100:Oxygen