title: Expression of inhibins, activins, insulin-like growth factor-I and steroidogenic enzymes in the equine placenta.
abstract: In this study, the expression patterns of inhibins, activins, insulin-like growth factor-I (IGF-I) and steroidogenic enzymes in equine placentae recovered during the latter two-thirds of gestation were examined. Concentrations of inhibin A and inhibin pro-alphaC in endometrial and fetal placental tissue homogenates were very low during the period examined, whereas these tissues contained high concentrations of activin A. In both maternal endometrial and fetal placental tissues, activin A levels decreased as pregnancy progressed. Expression of inhibin alpha-subunit was not observed in the placenta using either immunohistochemistry or in situ hybridization. Inhibin/activin betaA-subunit and its mRNA were confined to maternal endometrial glands, whereas immunopositive betaB-subunit was not detected in either endometrial glands or microcotyledons. Cytochrome P450 side chain cleavage enzyme was detected by immunohistochemistry in both endometrial glands and microcotyledons, whereas cytochrome P450 17alpha-hydroxylase/lyase was absent in these tissues. Immunopositive signals for 3beta-hydroxysteroid dehydrogenase and cytochrome P450 aromatase were localized in microcotyledons but not in endometrial glands. Immunohistochemistry revealed that IGF-I was highly expressed in microcotyledons around Day 130, and decreased as pregnancy progressed. Changes in the expression of IGF-I were correlated with the number of PCNA positive cells in the placenta. The present study demonstrated the presence and localized the site of expression of activin, IGF-I and steroidogenic enzymes in equine placental tissues during the latter two-thirds of gestation; the results suggest that activin and IGF-I may be involved in the regulation of placental development.
authors.affiliation: Department of Tissue Physiology, Tokyo University of Agriculture and Technology, Tokyo 183-8509, Japan.
authors.forename: Koji Y
authors.initials: KY
authors.lastname: Arai
authors.forename: Yumiko
authors.initials: Y
authors.lastname: Tanaka
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Taniyama
authors.forename: Noboru
authors.initials: N
authors.lastname: Tsunoda
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Nambo
authors.forename: Natsuko
authors.initials: N
authors.lastname: Nagamine
authors.forename: Gen
authors.initials: G
authors.lastname: Watanabe
authors.forename: Kazuyoshi
authors.initials: K
authors.lastname: Taya
mesh_terms: D015096:3-Hydroxysteroid Dehydrogenases / Q000096:biosynthesis; D028341:Activins / Q000096:biosynthesis* / Q000235:genetics; D000818:Animals; D001141:Aromatase / Q000096:biosynthesis; D004717:Endometrium / Q000378:metabolism; D005260:Female; D006736:Horses / Q000378:metabolism*; D007150:Immunohistochemistry; D017403:In Situ Hybridization; D028322:Inhibin-beta Subunits / Q000096:biosynthesis* / Q000235:genetics; D007265:Inhibins / Q000096:biosynthesis* / Q000235:genetics / Q000502:physiology; D007334:Insulin-Like Growth Factor I / Q000096:biosynthesis*; D008297:Male; D010920:Placenta / Q000201:enzymology* / Q000378:metabolism*; D011247:Pregnancy; D018809:Proliferating Cell Nuclear Antigen / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics
chemical_list: D018809:Proliferating Cell Nuclear Antigen; D012333:RNA, Messenger; C422405:activin A; C422362:inhibin A; C094377:inhibin-alpha subunit; D028341:Activins; D007265:Inhibins; D007334:Insulin-Like Growth Factor I; D028322:Inhibin-beta Subunits; D015096:3-Hydroxysteroid Dehydrogenases; D001141:Aromatase