Binding of insulin-like growth factor-I to rat uterus; variations during sensitization and decidualization.
IGF-I receptors have been identified and characterized in a variety of tissues. In this study receptors for IGF-I in the rat uterine tissue were identified and characterized. We have demonstrated IGF-I receptors in crude uterine membranes by binding and cross-linking experiments. IGF-I binding to the rat uterine membranes displayed time, temperature and pH dependance, and optimal binding conditions were achieved by 20 h of incubation at 4 degrees C, at a pH of 7.8. Uterine IGF-I binding sites were specific for binding IGF-I peptide and demonstrated less than 100 x lower affinity for insulin. The binding was reversible and Scatchard analysis indicated presence of a single class of binding sites with an apparent dissociation constant of 1.68 +/- 0.24 nmol/l and Bmax of 0.82 +/- 0.1 pmol/mg protein. During estrogen treatment, sensitization and decidualization there was an overall increase of membrane proteins in the uterus and a relative decrease of IGF-I receptors per unit of protein. When expressed on a per uterus basis, there was a progressive increment in total IGF-I binding in estradiol-treated, sensitized, and decidualized uterus compared with controls. These data indicate a possible role for IGF-I in uterine cell multiplication and further differentiation to decidual cells in response to deciduogenic stimuli.
Chandrasekhar
Y
Y
Department of Obstetrics and Gynecology, University of Texas Medical Branch, Galveston.
Narayan
S
S
Singh
P
P
Nagamani
M
M
D000818:Animals; D001345:Autoradiography; D001665:Binding Sites; D002454:Cell Differentiation / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D003656:Decidua / Q000187:drug effects* / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology; D005260:Female; D006863:Hydrogen-Ion Concentration; D007328:Insulin / Q000494:pharmacology; D007334:Insulin-Like Growth Factor I / Q000737:chemistry / Q000378:metabolism* / Q000494:pharmacology; D008565:Membrane Proteins / Q000494:pharmacology; D010052:Ovariectomy; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000737:chemistry / Q000187:drug effects* / Q000378:metabolism; D017451:Receptors, Somatomedin; D014599:Uterus / Q000187:drug effects / Q000378:metabolism*
D007328:Insulin; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D004958:Estradiol; D007334:Insulin-Like Growth Factor I