Effects of cysteamine, FSH and estradiol-17 beta on in vitro maturation ofporcine oocytes

Porcine cumulus-oocyte complexes (COCs) were cultured for 48 h with additio n or absence of exogenous estradiol-17 beta (E-2; 1 mug/mL) in the maturati on medium (mM199). The medium was supplemented with sodium pyruvate (0.1 mg /mL), 10% (v/v) FCS, various concentrations of FSH (0, 1 and 10 mug/mL) and with or without cysteamine (150 muM). When supplemented with E-2, cysteami ne enhanced the rates of germinal vesicle breakdown (GVBD) and maturation t o metaphase-II(M-II) in COCs cultured in the medium with 0 and 1 mug/mL FSH (P<0.05). Among COCs cultured with FSH, oocytes cultured with 1 <mu>g/mL F SH and E-2 but without cysteamine showed the lowest rates of GVBD and M-II. The rates were, however, significantly increased when cysteamine was added to the same medium or by increasing FSH concentration to 10 mug/mL in the maturation medium. E-2 significantly inhibited the rates of GVBD and M-II i n COCs cultured without FSH and cysteamine (a group of oocytes with spontan eous maturation). When COCs were cultured in TCM 199 with 1 or 10 mug/mL FS H, with or without E-2 (1 mug/mL) and fertilized in vitro, the rates of mal e pronucleus formation were not increased by increasing FSH concentration, but the addition of cysteamine to the maturation medium significantly enhan ced the rates in the same FSH treatment. The results indicate that E-2 inhi bits spontaneous GVBD and maturation to M-II of porcine oocytes and that a low concentration of FSH (1 mug/mL) is not sufficient to induce full nuclea r maturation, compared with 10 mug/mL FSH, but that, it can complete nuclea r maturation with cysteamine and E-2. However, the cytoplasmic maturation i s promoted only by the addition of cysteamine in the medium. (C) 2001 by El sevier Science Inc.