Hormonal control of uteroglobin secretion in rabbit uterus. Inhibition of uteroglobin synthesis and messenger ribonucleic acid accumulation by oestrogen and anti-oestrogen administration

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Abstract
Uteroglobin mRNA activity and uteroglobin secretion in rabbit uterus after administration of progesterone and 5.alpha.-dihydrotestosterone, either alone or concomitantly with estradiol-17.beta. and tamoxifen, a non-steroidal anti-estrogen, were quantified. Poly(A)-containing mRNA was isolated from the uterine tissue by extraction with phenol/chloroform, precipitation with ethanol and chromatography on oligo(dT)-cellulose. Cell-free translation in vitro of the poly(A)-containing mRNA was carried out in a wheat-germ lysate, and the product isolated by specific immunoprecipitation with anti-uteroglobin antiserum purified by affinity chromatography. Radioimmunoassay was utilized to determine uteroglobin content if the uterine flushings and tissue preparations. When given for 5 days, both progesterone (1 mg/kg per day) and 5.alpha.-dihydrotestosterone (25 mg/kg per day) elicited a marked induction of uteroglobin secretion, which was accompanied with accumulation of uteroglobin mRNA in the tissue. Concomitant administration of estradiol-17.beta. (50 .mu.g/kg per day) or tamoxifen (12.5 mg/kg per day) significantly decreased both progesterone- and 5.alpha.-dihydrotestosterone-induced uteroglobin secretion, with a parallel decrease in the uteroglobin-mRNA activity. The decline in the uteroglobin content of the uterine flushes brought about by estradiol-17.beta. or tamoxifen administration was not due to inhibition of secretion of this protein by the endometrial cells, since a simultaneous decrease occurred in the tissue uteroglobin content. After 1 5-day pretreatment with progesterone (1 mg/kg per day), administration of estradiol-17.beta. (50 .mu.g/kg per day) during the ensuing 4 days greatly accelerated the decay of the uteroglobin content in the uterine fluid.