Effects of transforming growth factors and activin-A on in vitro porcine oocyte maturation.
Growth factors are known to regulate ovarian function. In the present study, effects of these growth factors, TGF-alpha, TGF-beta, and activin-A were tested on spontaneous porcine oocyte maturation. Cumulus-oocyte complexes (COC) were cultured in the presence of TGF-alpha, TGF-beta, and activin-A for 48 hr. Stages of meiotic maturation were assessed by staining with acetic orcein. Among these factors, only TGF-alpha significantly enhanced the maturation rate, whereas TGF-beta suppressed the spontaneous maturation rate. The site of action of TGF-alpha on COC and the interaction between TGF-alpha and EGF receptor was also examined. Denuded oocytes, alone or in coculture with cumulus cells, were cultured in the presence of TGF-alpha for 48 hr. TGF-alpha did not have any significant effect on denuded oocyte maturation. Heptanol was employed to investigate the role of gap junctions on TGF-alpha-induced oocyte maturation in COC. Although heptanol did not have any significant effect in the control medium, heptanol reversed the stimulatory effect of TGF-alpha on porcine oocyte maturation. TGF-alpha was able to displace 125I-EGF binding on COC. In conclusion, TGF-alpha enhances the spontaneous maturation of porcine oocytes by generating positive signal(s) in cumulus cells that are transferred to the oocyte via gap junctions. TGF-alpha shares the same receptor with EGF on porcine COC. TGF-beta, in contrast, inhibits porcine oocyte maturation.
Coskun
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Department of Veterinary Physiology and Pharmacology, College of Veterinary Medicine, Ohio State University, Columbus 43210-1092.
Lin
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YC
D028341:Activins; D000438:Alcohols / Q000494:pharmacology; D000818:Animals; D004815:Epidermal Growth Factor / Q000378:metabolism; D005260:Female; D017629:Gap Junctions / Q000187:drug effects / Q000378:metabolism; D006133:Growth Substances / Q000494:pharmacology; D019850:Heptanol; D066298:In Vitro Techniques; D007265:Inhibins / Q000494:pharmacology*; D009865:Oocytes / Q000187:drug effects* / Q000254:growth & development / Q000378:metabolism; D013552:Swine; D016211:Transforming Growth Factor alpha / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D016212:Transforming Growth Factor beta / Q000494:pharmacology*
D000438:Alcohols; D006133:Growth Substances; D016211:Transforming Growth Factor alpha; D016212:Transforming Growth Factor beta; D028341:Activins; D007265:Inhibins; D004815:Epidermal Growth Factor; D019850:Heptanol