Hormonal control of uteroglobin secretion and preuteroglobin mRNA content in rabbit endometrium

The cellular content of preuteroglobin mRNA in endometrium was measured by molecular hybridization to preuteroglobin cDNA, and compared with uteroglobin content in the uterine secretion as determined by radioimmunoassay. The following results were obtained. (1) A single injection of either estradiol or progesterone leads to a rapid accumulation of preuteroglobin mRNA in the endometrium, but has no effect on the cellular content of preuteroglobin mRNA in the lung. (2) The effect of progesterone on uteroglobin on secretion parallels its influence on preuteroglobin mRNA levels, but estradiol has a more pronounced effect on the mRNA content than on uteroglobin secretion. (3) 5 days after priming with estradiol, a single injection of progesterone leads to the accumulation of preuteroglobin mRNA sequences without measurable lag phase, whereas a lag period is found if progesterone is administered earlier after estradiol treatment. (4) In the endometrium of pseudopregnant rabbits there are around 10 000 molecules of preuteroglobin mRNA per epithelial cell as compared with 300 in control estrous rabbits, and 1000-2000 in animals treated with estradiol alone. (5) Following maximal induction, the apparent half-life of uteroglobin and its mRNA are inversely influenced by estrogens: estradiol accelerates the disappearance of uteroglobin from the uterine secretion, and retards the decay of preuteroglobin mRNA sequences in endometrium.