title: Synthesis and inducibility of the Uterine estrogen-induced protein, IP, during the rat estrous cycle: clues to uterine estrogen sensitivity.
abstract: Analysis of newly labeled soluble proteins in uteri of mature rats throughout the estrous cycle indicates that the relative rate of synthesis of the uterine estrogen-induced protein, IP, is high at proestrus, when endogenous estrogen secretion is maximal; it is not synthesized at detectable levels at estrus and metestrus; and some minimal synthesis is seen in diestrus uteri. Injection of exogenous estrogen results in some increase in the IP synthesis rate at proestrus; slight induction of IP synthesis at estrus; and maximal induction (as great as that induced in the mature, ovariectomized uterus by estrogen) at metestrus and diestrus. Studies in the immature (day 21-24) rat, aimed at determining the possible causes of the uterine recalcitrance to exogenous estrogen seen at estrus, indicate that one can reproduce in the immature uterus a period of feeble responsiveness to a second injection of estrogen after exposure to a first, high dose of estrogen. After a single injection of estrogen, there is a lag between the gradual return of full IP inducibility (requiring over 40 hours to reach the control level) and the return of nuclear-translocatable receptor (at control level by 24 hr). This suggests that in addition to the presence of nuclear-translocatable receptor, the response to a second injection of estrogen is dependent upon other factors whose replenishment and/or reactivation is slower than that of the receptor.
mesh_terms: D000367:Age Factors; D000818:Animals; D002369:Castration; D002467:Cell Nucleus / Q000378:metabolism; D003600:Cytosol / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D004958:Estradiol / Q000494:pharmacology*; D004971:Estrus; D005260:Female; D066298:In Vitro Techniques; D007930:Leucine / Q000378:metabolism; D011247:Pregnancy; D014176:Protein Biosynthesis; D011506:Proteins / Q000302:isolation & purification / Q000494:pharmacology; D051381:Rats; D011956:Receptors, Cell Surface; D013997:Time Factors; D014599:Uterus / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D011506:Proteins; D011956:Receptors, Cell Surface; D004958:Estradiol; D007930:Leucine