Effect of IGF-I on pig oocyte maturation, fertilization, and early embryonic development in vitro, and on granulosa and cumulus cell biosynthetic activity.
Porcine granulosa cells have been shown previously to both secrete and respond to insulin-like growth factor-I (IGF-I), suggesting an autocrine function of this peptide in the follicle. The present work was undertaken to determine possible effects of IGF-I on in vitro maturation, in vitro fertilization, and early embryonic development in culture. Granulosa and cumulus cell proliferation and differentiation based on 3H-thymidine uptake and progesterone production, respectively, were also assessed. The results showed that the cleavage rate of oocytes was markedly stimulated in a dose-dependent manner by the addition of IGF-I to the oocyte maturation medium (P < 0.05). Embryo development beyond the 8-cell stage was improved by IGF-I, reaching a maximum of 22% at 200 ng/ml IGF-I. Treatment with IGF-I after fertilization increased the percentage of total oocyte cleavage (P < 0.05) to approximately 52%, 43%, and 57% at, respectively, 25, 50, and 100 ng/ml IGF-I. 3H-thymidine incorporation by granulosa cells was significantly increased in cultures treated with FSH (3-fold) or IGF-I (6-fold) compared to the control. For the cumulus cells, FSH caused a similar increase (3-fold) in 3H-thymidine incorporation while IGF-I stimulated a 15-fold increase. Progesterone production by the granulosa cells was increased to the same extent by treatment with FSH or IGF-I (4.7 and 5.1-fold, respectively). However, for the cumulus cells, while FSH caused a marked 16-fold increase in progesterone production, IGF-I caused only a marginal increase of 2.5-fold.(ABSTRACT TRUNCATED AT 250 WORDS)
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Department of Obstetrics and Gynaecology, University of Western Ontario, London.
Tekpetey
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Armstrong
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D000818:Animals; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D006063:Chorionic Gonadotropin / Q000494:pharmacology; D002970:Cleavage Stage, Ovum / Q000187:drug effects / Q000378:metabolism; D005314:Embryonic and Fetal Development / Q000187:drug effects*; D005260:Female; D005306:Fertilization / Q000187:drug effects*; D005307:Fertilization in Vitro; D005640:Follicle Stimulating Hormone / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects; D006064:Gonadotropins, Equine / Q000494:pharmacology; D006107:Granulosa Cells / Q000187:drug effects / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000494:pharmacology*; D009866:Oogenesis / Q000187:drug effects*; D006080:Ovarian Follicle / Q000187:drug effects* / Q000378:metabolism; D011374:Progesterone / Q000096:biosynthesis*; D013552:Swine / Q000196:embryology / Q000502:physiology
D006063:Chorionic Gonadotropin; D006064:Gonadotropins, Equine; D011374:Progesterone; D007334:Insulin-Like Growth Factor I; D005640:Follicle Stimulating Hormone