Effect of crude canine pituitary extract (cCPE) on the in vitro production of progesterone and nuclear maturation of canine oocytes

Abstract

We examined the effect of crude canine pituitary extract (cCPE) on the in vitro nuclear maturation of canine oocytes and production of progesterone by cumulus cells. cCPE was extracted from canine pituitaries and the concentrations of canine follicle stimulating hormone (FSH) and luteinizing hormone (LH) were determined. Cumulus oocyte complexes (COCs) were harvested from anestrus cycle ovaries and matured in NCSU-37 supplemented with 10% estrus bitch serum, 50 μg/ml gentamycin and 0, 40 or 400 μg/ml cCPE at 38°C in a humidified atmosphere of 5% CO₂ for 72 h. The nuclear maturation of the oocytes and the level of progesterone in the culture medium were evaluated. Development to metaphase I (MI) - metaphase II (MII) of canine oocytes in 400 μg/ml cCPE (15.4%) was significantly higher than in 0 and 40 μg/ml cCPE (4.3 and 8.7%), respectively. Treatment with 40 and 400 μg/ml cCPE also generated 0.33 and 0.65 ng/ml progesterone in the culture medium, respectively. Thus, the addition of cCPE to the culture medium promotes the nuclear maturation of canine oocytes and elevates the production of progesterone by cumulus cells.

Key words: In vitro maturation, pituitary extract, canine oocyte.