Modulatory effects of steroid hormones, oxytocin, arachidonic acid, forskolin and cyclic AMP on the expression of aquaporin 1 and aquaporin 5 in the porcine uterus during placentation.

Aquaporins (AQPs) are proteins forming trans-membrane channels responsible for water transport. AQP1 and AQP5 are present in structures of the female reproductive system. In the uterus, these AQPs are involved in water movement between the intraluminal, interstitial and capillary compartments and their uterine expression is essential throughout the pregnancy, including its early stages. Thus, the study aimed to assess the influence of P4 (progesterone), E2 (estradiol), OT (oxytocin), AA (arachidonic acid), cAMP and FSK (forskolin) on the AQP1 and AQP5 mRNA and protein expression in the uterine tissue of gilts on Days 30 - 32 of gestation (the placentation period), following short (3 h) and long (24 h) incubations. Steroid hormones influenced the expression of AQP1 and AQP5; E2 up-regulated, but P4 down-regulated mRNAs of these AQPs, whereas the protein level of studied AQPs was increased by both steroids. OT treatment decreased AQP1 (after 24 h), but increased AQP5 (after 3 h) mRNA expression. Treatment with AA significantly reduced the AQP1 expression at the mRNA level, but stimulated at the protein level. The expression of AQP5 mRNA and protein was stimulated by AA. FSK markedly decreased AQP1 mRNA, but increased of AQP5 after 3-h incubation. In turn, cAMP stimulated and inhibited transcription of AQP5 after 3- and 24-h incubations, respectively. Immunohistochemical analysis confirmed the uterine localization of AQP1 in the apical and basal membranes of endothelial cells and AQP5 in the apical membranes of epithelial cells under control condition. Treatments with P4, E2, AA, cAMP or FSK have caused additional appearance of AQP5 labeling in the basolateral membranes of epithelial cells. These results suggest a participation of steroid hormones (P4 and E2), AA derivatives and cAMP in controlling the expression of AQP1 and AQP5 as well as the distribution of AQP5 in the uterine tissue of pregnant gilts during placentation (Days 30 - 32 of gestation).

Expression of aquaporin 1 and 5 and their regulation by ovarian hormones, arachidonic acid, forskolin and cAMP during implantation in pigs.

Aquaporin proteins (AQPs) are a family of channels expressed in numerous mammalian tissues, where they play a fundamental role in regulating water transport across cell membranes. Based on reports that AQPs are present in the reproductive system and participate in reproductive processes, our aim was to investigate the effect of progesterone (P(4)), estradiol (E(2)), oxytocin (OT), arachidonic acid (AA), forskolin (FSK) and cyclic adenosine monophosphate (cAMP) on AQP1 and AQP5 expression at mRNA and protein levels in porcine uterine explants from Days 14-16 of gestation in order to determine if they play a role in implantation period in pigs. Quantitative real time PCR and Western-blot analysis revealed that the uterine explants treated with FSK and cAMP produce delayed, but long-term effects on AQP1 abundance (24 h) while AQP5 had a rapid and sustained response to FSK and cAMP in protein content (3 and 24 h). AA increases gene and protein content of AQP1 after longer exposition whereas AQP5 increases after 3 h only at the protein level. Both AQPs potentially remains under control of steroid hormones. OT has been shown to increase AQP1, and decrease AQP5 mRNA, without visible changes in protein content. P(4), E(2), AA, FSK and cAMP caused the appearance of AQP5 expression in the basolateral plasma membrane of the epithelial cells. The staining represents most likely AQP5 functioning mechanism for both absorption and reabsorption across the glandular epithelium.

Expression of aquaporin 1, 5 and 9 in the ovarian follicles of cycling and early pregnant pigs.

Aquaporins (AQPs) are water channel proteins responsible for water homeostasis and important for proper functioning of all body systems, including reproductive structures. This study was designed to determine their localization and quantitative changes in the pig ovary during different stages of the estrous cycle and early pregnancy. The expression of AQP 1, 5 and 9 proteins was determined by immunocytochemistry and Western blot analyses. AQP1 was found in the plasma membranes of capillary endothelium, AQP5 - in the plasma membranes of granulosa cells of developing follicles and flattened follicle cells of the primordial follicles, and AQP9 - in granulosa cells of the developing follicles. In the cyclic pigs, the expression of AQP1 and 5 proteins was the highest on Days 18-20, but did not change significantly between Days 2-4, 10-12 and 14-16 of the cycle. In pregnant pigs (Days 14-16 and 30-32), the expression of AQP1 and 5 did not change and was similar to that observed during Days 10-12 and 14-16. In turn, AQP9 expression did not change between all studied periods. In conclusion, studied AQP are localized in different cells populations, the endothelial and granulosa cells, and AQP1 and 5 seem to be crucial for follicular development in pigs.