Localization of the sites of synthesis and action of insulin-like growth factor-I in the rat uterus.
In this report we have used in situ hybridization to localize insulin-like growth factor-I (IGF-I) expression in the uterus and have examined the effects of exogenous IGF on 3H-methyl thymidine incorporation into DNA, in uterine sections in organ culture. IGF-I mRNA was detected in all layers of the uterus but was particularly abundant in the outer longitudinal smooth muscle layer. Although IGF-I mRNA was detectable in untreated, immature rat uteri, the abundance in each layer of the uterus was increased after 17 beta-estradiol (E2) administration. A similar increase was seen in uteri from ovariectomized, hypophysectomized rats treated with E2. IGF-I when added to uterine sections in organ culture had no significant effect on DNA synthesis in the absence of E2. However, a dose-dependent increase in DNA synthesis was seen in the presence of E2. The half-maximal and maximal responses required 1 and 10 ng IGF-I, respectively. Autoradiographic localization of 3H-methyl thymidine incorporation into DNA demonstrated that the majority of the DNA synthesis occurred in the stromal layer. These findings are consistent with the hypothesis that IGF-I may function as a paracrine growth factor, mediating stromal-myometrial cell interaction.
Ghahary
A
A
Department of Internal Medicine, Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
Chakrabarti
S
S
Murphy
L J
LJ
D000818:Animals; D001345:Autoradiography; D004247:DNA / Q000187:drug effects / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004958:Estradiol / Q000502:physiology; D005260:Female; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism* / Q000494:pharmacology; D008024:Ligands; D009693:Nucleic Acid Hybridization; D009924:Organ Culture Techniques; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011956:Receptors, Cell Surface / Q000378:metabolism; D017451:Receptors, Somatomedin; D013002:Somatomedins / Q000378:metabolism*; D013936:Thymidine / Q000378:metabolism; D014599:Uterus / Q000187:drug effects / Q000378:metabolism* / Q000648:ultrastructure
D008024:Ligands; D012333:RNA, Messenger; D011956:Receptors, Cell Surface; D017451:Receptors, Somatomedin; D013002:Somatomedins; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D004247:DNA; D013936:Thymidine