title: Effect of IGF-I on pig oocyte maturation, fertilization, and early embryonic development in vitro, and on granulosa and cumulus cell biosynthetic activity.
abstract: 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)
authors.affiliation: Department of Obstetrics and Gynaecology, University of Western Ontario, London.
authors.forename: P
authors.initials: P
authors.lastname: Xia
authors.forename: F R
authors.initials: FR
authors.lastname: Tekpetey
authors.forename: D T
authors.initials: DT
authors.lastname: Armstrong
mesh_terms: 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
chemical_list: D006063:Chorionic Gonadotropin; D006064:Gonadotropins, Equine; D011374:Progesterone; D007334:Insulin-Like Growth Factor I; D005640:Follicle Stimulating Hormone