Possible involvement of protein kinase C in gonadotropin-induced ovulation in the rat ovary.
Recent reports indicate that protein kinase C may play an important role in the process of gonadotropin-induced ovulation in the ovary. In the present study, we examined the effect of the protein kinase C inhibitor, 1-(5-isoquinolinesulfonyl)-2-methylpiperazine (H-7), on LH-stimulated tissue type plasminogen activator (tPA) activity in cultured rat granulosa cells. Granulosa cells were obtained from PMSG-treated rats and cultured for 48 h in the presence or absence of H-7 (0.1-60 microM) with ovine LH (30 ng/ml), phorbol 12-myristate 13-acetate (10(-8) M), phorbol 12,13-dibutyrate (10(-8) M), or (Bu)2cAMP (5 mM). After culture, tPA activity in the conditioned medium was assayed by fibrin autography technique after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. H-7 (1.0-60 microM) inhibited LH-, phorbol 12-myristate 13-acetate-, or phorbol 12,13-dibutyrate-stimulated tPA activity dose dependently, and each ID50 was approximately 8 microM. However, H-7 did not inhibit (Bu)2cAMP-stimulated tPA activity. To investigate the effect of H-7 on the ovulatory process in vivo, PMSG-treated immature rats were injected with H-7 (10(-9)-10(-3) M) into the unilateral ovarian bursa just before human CG administration. After 24 h, the number of oocyte-cumulus complexes in the oviduct was counted. H-7 suppressed the number of oocytes released from treated ovaries dose-dependently. The light microscopical observation revealed that ovaries treated with H-7 contained a few corpora lutea and many large unruptured follicles. The results of the present study suggest that the suppressive effects of H-7 on human CG-induced ovulation might be partly due to the inhibition of tPA secretion by rat granulosa cells via protein kinase C inhibition.
Shimamoto
T
T
Department of Obstetrics and Gynecology, Wakayama Medical College, Japan.
Yamoto
M
M
Nakano
R
R
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000818:Animals; D003994:Bucladesine / Q000494:pharmacology; D002478:Cells, Cultured; D005260:Female; D006064:Gonadotropins, Equine / Q000494:pharmacology; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism*; D007546:Isoquinolines / Q000494:pharmacology; D007986:Luteinizing Hormone / Q000494:pharmacology*; D010053:Ovary / Q000166:cytology / Q000187:drug effects / Q000502:physiology; D010060:Ovulation / Q000187:drug effects*; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D010959:Tissue Plasminogen Activator / Q000378:metabolism*
D006064:Gonadotropins, Equine; D007546:Isoquinolines; D010879:Piperazines; D015240:Phorbol 12,13-Dibutyrate; D003994:Bucladesine; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D007986:Luteinizing Hormone; D011493:Protein Kinase C; D010959:Tissue Plasminogen Activator; D013755:Tetradecanoylphorbol Acetate