Regulation of uterine insulin-like growth factor I mRNA and insulin-like growth factor II mRNA by estrogen in the rat.
IGF-I and IGF-II are peptides with mitogenic properties. In this study mRNA for IGF-I and IGF-II was analysed in rat uterine tissue after different endocrine manipulations and the possibility of an estrogenic regulation of IGF expression was investigated. Both IGF-I and IGF-II mRNA were present in uterine tissue. The level of IGF-I mRNA, but not IGF-II mRNA, was reduced following ovariectomy. Administration of estradiol (2.5 micrograms/day for 4 days) to ovariectomized rats increased IGF-I mRNA 8-fold to levels seen in intact animals. In adult animals hepatic IGF-I mRNA did not appear to be increased by estrogen treatment. Low levels of IGF-II mRNA were detected in the uterus, but showed no dependence on estrogen. The inductive effect of estrogen on uterine IGF-I mRNA could not be substituted for by growth hormone administration (0.5 mg/100 g, ip for 6 h). The present results suggest IGF-I as a potential candidate for a mediator of estrogen-induced growth. Both estrogen and GH induce IGF-I mRNA and a tissue specificity for these hormones is indicated where GH regulates hepatic and estrogen uterine IGF-I mRNA.
Norstedt
G
G
Department of Medical Nutrition, Huddinge University Hospital, Karolinska Institute, Sweden.
Levinovitz
A
A
Eriksson
H
H
D000818:Animals; D004958:Estradiol / Q000008:administration & dosage*; D005260:Female; D013006:Growth Hormone / Q000008:administration & dosage; D007334:Insulin-Like Growth Factor I / Q000235:genetics / Q000378:metabolism*; D007335:Insulin-Like Growth Factor II / Q000235:genetics / Q000378:metabolism*; D008099:Liver / Q000378:metabolism; D008297:Male; D009693:Nucleic Acid Hybridization; D010052:Ovariectomy; D012333:RNA, Messenger / Q000378:metabolism*; D051381:Rats; D011919:Rats, Inbred Strains; D013002:Somatomedins / Q000378:metabolism*; D013997:Time Factors; D014599:Uterus / Q000378:metabolism*
D012333:RNA, Messenger; D013002:Somatomedins; D004958:Estradiol; D007334:Insulin-Like Growth Factor I; D007335:Insulin-Like Growth Factor II; D013006:Growth Hormone