Effect of adenylate cyclase stimulation on meiotic resumption and cyclic AMP content of zona-free and cumulus-enclosed bovine oocytes in vitro.
The effect of adenylate cyclase stimulation via the components of the enzyme on nuclear maturation in bovine cumulus-enclosed and zona-free oocytes was examined. The stimulating agents were cholera toxin, pertussis toxin, forskolin, sodium fluoride and prostaglandin E2. Cyclic AMP contents were measured in cumulus-oocyte complexes, cumulus-enclosed oocytes and in zona-free oocytes after stimulation, to establish the relationship between cumulus cell and oocyte cAMP concentrations and the meiotic status of the oocyte. In cumulus-enclosed oocytes, forskolin alone and 3-isobutyl-1-methylxanthine (IBMX), at 0.5 mmol l-1, inhibited the resumption of meiosis after 8 h of culture; the other agents were without effect. After 24 h of culture, IBMX at 0.5 mmol l-1 was without effect, but at 2 mmol l-1 reduced the percentage of oocytes at the mature stage (51 versus 82% in control medium). Forskolin alone reduced the proportion of oocytes at the mature stage from 82 to 58%. Forskolin plus IBMX at 2 mmol l-1 and sodium fluoride plus IBMX at 2 mmol l-1 significantly diminished the maturation rate (6 and 17% mature oocytes, respectively). Cholera toxin (with IBMX) and forskolin (alone or with IBMX) stimulated the synthesis of high amounts of cAMP in complexes, but only forskolin had a significant effect on the cAMP contents of oocytes derived from complexes. Forskolin was more effective in zona-free oocytes than in cumulus-enclosed oocytes in inhibiting nuclear maturation (24% mature oocytes versus 73% in control medium) even after 24 h of culture; its effect was potentiated by IBMX; forskolin also stimulated cAMP synthesis.(ABSTRACT TRUNCATED AT 250 WORDS)
Bilodeau
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S
Département de Zootechnie, Faculté des Sciences de l'Agriculture et de l'Alimentation, Université Laval, Ste-Foy, Québec, Canada.
Fortier
M A
MA
Sirard
M A
MA
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D037361:Adenylate Cyclase Toxin; D000262:Adenylyl Cyclases / Q000378:metabolism*; D000818:Animals; D002417:Cattle; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D002772:Cholera Toxin / Q000494:pharmacology; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000378:metabolism*; D015232:Dinoprostone / Q000494:pharmacology; D005260:Female; D008540:Meiosis / Q000187:drug effects / Q000502:physiology*; D009865:Oocytes / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D006080:Ovarian Follicle / Q000502:physiology*; D037342:Pertussis Toxin; D012969:Sodium Fluoride / Q000494:pharmacology; D013268:Stimulation, Chemical; D010566:Virulence Factors, Bordetella / Q000494:pharmacology; D015044:Zona Pellucida / Q000502:physiology
D037361:Adenylate Cyclase Toxin; D010566:Virulence Factors, Bordetella; D005576:Colforsin; D012969:Sodium Fluoride; D002772:Cholera Toxin; D000242:Cyclic AMP; D037342:Pertussis Toxin; D000262:Adenylyl Cyclases; D015232:Dinoprostone; D015056:1-Methyl-3-isobutylxanthine