Follicle-stimulating hormone and growth hormone act differently on nuclear maturation while both enhance developmental competence of in vitro matured bovine oocytes

• Published in: Molecular reproduction and development 1998-11, Vol.51 (3), p.339-345
• Main Authors: Izadyar, F, Zeinstra, E, Bevers, M.M
• Format: Article
• Language: English
• Subjects: Animals; Biological and medical sciences; bovine; cAMP; Cattle; Cell Differentiation - drug effects; Cell Nucleus - drug effects; Cells, Cultured; cyclic AMP; Early stages. Segmentation. Gastrulation. Neurulation; embryogenesis; Embryology: invertebrates and vertebrates. Teratology; Female; fertilization (reproduction); Follicle Stimulating Hormone - pharmacology; follicle-stimulating hormone; FSH; Fundamental and applied biological sciences. Psychology; Growth Hormone - pharmacology; Hormone metabolism and regulation; in vitro; Mammalian female genital system; maturation; nuclei; oocyte; oocytes; Oocytes - cytology; Oocytes - drug effects; somatotropin; Vertebrates: reproduction
• ISSN: 1040-452X; 1098-2795
• DOI: 10.1002/(SICI)1098-2795(199811)51:3<339::AID-MRD14>3.0.CO;2-Y

This study was designed to investigate the effect of follicle‐stimulating hormone (FSH) on nuclear maturation, fertilization, and early embryonic development of in‐vitro‐matured bovine oocytes and to find out whether this effect is exerted through a cyclic adenosine monophosphate (cAMP) signal transduction pathway. In addition the effect of the combination of FSH and growth hormone (GH) on subsequent cleavage and embryo development was studied. Therefore cumulus oocyte complexes were cultured in the presence of FSH (0.05 IU/ml) and the nuclear stage of the oocytes was assessed using 4,6‐diamino‐2‐phenyl‐indole (DAPI) staining either after 16, 20, or 24 hr of in vitro maturation or 18 hr after the onset of fertilization. To assess the effect of FSH and the combination of FSH and GH added during in vitro maturation on the developmental capacity of the oocytes, cumulus oocyte complexes were incubated in the presence of either FSH (0.05 IU/ml) or FSH (0.05 IU/ml) plus GH (100 ng/ml) for 22 hr, followed by in vitro fertilization and in vitro embryo culture. To investigate whether FSH‐induced oocyte maturation is exerted through the cAMP pathway, cumulus oocyte complexes were cultured in M199 supplemented with FSH (0.05 IU/ml) and H‐89 (10 μM), a specific inhibitor of cAMP‐dependent protein kinase A. After 16 hr of culture, the proportion of oocytes in metaphase II (MII) stage was determined. Cultures with GH and without FSH and H‐89 served as controls. The percentage of MII oocytes at 16 hr of incubation was significantly lower (P < 0.001) in the presence of FSH than in the control group, while the number of MII oocytes beyond 20 hr did not differ from the control group. That points to a transient inhibition of nuclear maturation by FSH. Opposite to FSH, addition of GH during in vitro maturation significantly enhanced the number of MII oocytes after 16 hr of culture (P < 0.001), which points to the acceleration of nuclear maturation by GH. Addition of FSH during in vitro maturation significantly enhanced the proportion of normal fertilized oocytes, cleaved embryos and blastocysts (P < 0.001). Similarly, addition of GH during in vitro maturation significantly enhanced the number of cleaved embryos and blastocysts (P < 0.001); however, in vitro maturation in the presence of GH and FSH did not result in an extra enhancement of the embryo development. Both the inhibition of nuclear maturation by FSH and its acceleration by GH was completely abolished by H‐89. In co