Localization of progesterone receptor isoform A in the uterus of non- pregnant sows and maternal placenta during early gestation
Abstract
The progesterone (P4) produced by the corpus luteum, plays a vital role in the preparation, reception of embryos and maintenance of pregnancy. Its effects are mediated by the interaction with its specific intracellular receptors. The aim of this study was to investigate the localization of the progesterone receptor isoform A (PRA) in histological endometrial samples from crossbred pregnant and non-pregnant sows, and the relationship with plasma P4 levels. Nonpregnant sows in the follicular phase and pregnant sows at days 5, 17 and 35 of gestation (n=16) were used. The localization of the PRA was determined by immunohistochemistry with monoclonal antibodies. In the endometrium of nonpregnant and pregnant sows at day 5 of gestation PRA expression was observed in the nuclei of epithelium cells, uterine glands, stroma and myometrium. While on day 17 of gestation PRA expression was found in glands, stroma and myometrium, and on day 35 the expression was observed in the stroma and myometrium. An increase in serum P4 concentrations was found on day 17 of gestation. The localization and variations in the score for PRA in different cell types may reflect a cell-specific influence of progesterone, which might be explained by increasing P4 levels during the «window of implantation»
