Influence of meiotic inhibition by butyrolactone-I during germinal vesicle stage on the ability of porcine oocytes to be activated by electric stimulation after nuclear maturation.
Butyrolactone-I (BL-I) is a specific inhibitor of cyclin-dependent kinases and prevents germinal vesicle breakdown (GVBD) in porcine oocytes. This study first focused on the effect of BL-I on the time course of GVBD and progression to metaphase II (MII) in oocytes after the removal of BL-I. When porcine oocytes were treated with 20 microM BL-I for 28 h, the intervals taken to undergo GVBD and progress to MII were 4-8 h and 16-20 h after washing out BL-I, respectively. These intervals were both approximately 8 h behind those of the control oocytes. When the BL-I treatment was performed for 20 h, instead of 28 h, there were no differences in the timing or frequency of progression to MII between the BL-I treatment and control groups. To determine whether the cytoplasmic maturation was the same, the ability of oocytes to form a female pronucleus in response to an electric stimulus was examined. When oocytes were stimulated at 28 h after the removal of BL-I, the rate of pronucleus formation was significantly lower in oocytes treated with BL-I than in untreated oocytes, despite the fact that both groups reached MII at a similar time. When the electric stimulus was given at 36 h after the removal of BL-I, oocytes had a pronucleus formation rate comparable to that of control oocytes. Therefore, the findings suggest that BL-I treatment of porcine oocytes at the germinal vesicle stage affects not only the progression of meiosis, but also the events involved in cytoplasmic maturation.
Hirao
Yuji
Y
Department of Animal Production and Grasslands Farming, National Agricultural Research Center for Tohoku Region, Morioka, Iwate, Japan. yujih@affrc.go.jp
Nishimoto
Namiko
N
Kure-bayashi
Satoshi
S
Takenouchi
Naoki
N
Yamauchi
Nobuhiko
N
Masuda
Hiroshi
H
Nagai
Takashi
T
D015107:4-Butyrolactone / Q000031:analogs & derivatives* / Q000494:pharmacology*; D000818:Animals; D002467:Cell Nucleus / Q000187:drug effects; D002478:Cells, Cultured; D003593:Cytoplasm / Q000187:drug effects / Q000502:physiology; D004558:Electric Stimulation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D005260:Female; D008540:Meiosis; D009865:Oocytes / Q000187:drug effects* / Q000502:physiology*; D013552:Swine; D013997:Time Factors
D004791:Enzyme Inhibitors; C082868:butyrolactone I; D015107:4-Butyrolactone