title: Expression of insulin-like growth factor-I (IGF-I) and its receptor in the peri-implantation mouse uterus, and cell-specific regulation of IGF-I gene expression by estradiol and progesterone.
abstract: This study describes the expression of insulin-like growth factor-I (IGF-I) and IGF-I receptor (IGF-IR) genes in the mouse uterus during the peri-implantation period (Days 1-6 of pregnancy), as well as effects of estradiol (E) and progesterone (P) on cell-specific IGF-I gene expression in the uterus of the ovariectomized adult mouse. Northern blot analysis showed that IGF-I mRNA levels were low but readily detectable in the uterus on Day 1 of pregnancy and steadily increased, reaching high levels just before (Day 4) and after initiation of implantation (Days 5 and 6). In general, IGF-IR transcripts were present in low abundance in uterine RNA throughout the peri-implantation period. However, six sizes of uterine IGF-IR transcripts were detected, and the relative abundance of two of these transcripts varied significantly during the peri-implantation period. Cell-specific expression of the IGF-I gene was examined by in situ hybridization to mRNA and immunohistochemical detection of protein. The results indicated that the synthesis of IGF-I on Days 1 and 2 was most predominant in glandular and luminal epithelial cells. However, on Days 3 and 4, stromal cells, and on Days 5 and 6, decidual cells appeared to be the predominant sites of synthesis of this growth factor. Uterine IGF-I gene expression was stimulated by ovarian steroids. Northern blot analysis showed that IGF-I transcripts were rare in the ovariectomized adult mouse uterus, but an injection of P and/or E caused a rapid accumulation of these transcripts. Analysis of the cell-specific expression of uterine IGF-I showed that E induced IGF-I gene expression primarily in epithelial cells, whereas P did so in the stroma. Superimposition of E on the P-primed uterus further stimulated IGF-I expression in the stroma. The results of these studies are consistent with an autocrine/paracrine function of uterine IGF-I, and indicate that ovarian steroids regulate the cell-specific and temporal patterns of expression of this gene in the peri-implantation mouse uterus.
authors.affiliation: Department of Obstetrics and Gynecology, Ralph L. Smith Research Center, University of Kansas Medical Center, Kansas City 66103.
authors.forename: S
authors.initials: S
authors.lastname: Kapur
authors.forename: H
authors.initials: H
authors.lastname: Tamada
authors.forename: S K
authors.initials: SK
authors.lastname: Dey
authors.forename: G K
authors.initials: GK
authors.lastname: Andrews
mesh_terms: D000818:Animals; D010064:Embryo Implantation / Q000235:genetics / Q000502:physiology; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects; D007150:Immunohistochemistry; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D011247:Pregnancy; D011374:Progesterone / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000187:drug effects / Q000378:metabolism*; D017451:Receptors, Somatomedin; D014599:Uterus / Q000187:drug effects / Q000378:metabolism*
chemical_list: D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D011374:Progesterone; D004958:Estradiol; D007334:Insulin-Like Growth Factor I