Expression of progesterone receptor membrane component (PGRMC) 1 and 2, serpine mRNA binding protein 1 (SERBP1) and nuclear progesterone receptor (PGR) in the bovine endometrium during the estrous cycle and the first trimester of pregnancy.

Progesterone (P4) is involved in the regulation of essential reproductive functions affecting the target cells through both nuclear progesterone receptors (PGRs) and membrane progesterone receptors. The aim of this study was to determine the mRNA and protein expression for PGRMC1, PGRMC2, SERBP1 and PGR within the bovine endometrium during the estrous cycle and the first trimester of pregnancy. There were no changes in PGRMC1 and PGRMC2 mRNA and protein expression during the estrous cycle, however, mRNA levels of PGRMC1 and PGRMC2 were increased (P<0.001) in pregnant animals. SERBP1 mRNA expression was increased (P<0.05), while the level of this protein was decreased (P<0.05) on days 11-16 of the estrous cycle. The expression of PGR mRNA was higher (P<0.01) on days 17-20 compared to days 6-10 and 11-16 of the estrous cycle and pregnancy. PGR-A and PGR-B protein levels were elevated on days 1-5 and 17-20 of the estrous cycle as compared to other stages of the cycle and during pregnancy. In conclusion, our results indicate that P4 may influence endometrial cells through both genomic and nongenomic way. This mechanism may contribute to the regulation of the estrous cycle and provide protection during pregnancy.

Daidzein affects steroidogenesis and oestrogen receptor expression in medium ovarian follicles of pigs.

Daidzein, a phytoestrogen present in soybean products used in swine feed, has been demonstrated to affect both reproductive and endocrine functions. The aims of this study were to examine the in vitro effects of daidzein on (1) progesterone (P4) and oestradiol (E2) secretion by porcine luteinised granulosa cells harvested from medium follicles, and (2) the mRNA and protein expression of oestrogen receptors α and ß (ERα and ERß) in these cells. The influence of E2 on P4 secretion and ERα and ERß expression in the granulosa cells of pigs was also investigated. It was found that daidzein inhibited progesterone secretion by luteinised granulosa cells isolated from medium follicles. In contrast, E2 did not affect progesterone production by these cells. Moreover, daidzein did not alter the granulosal secretion of E2. Both daidzein and E2 decreased mRNA expression of ERα in the cells examined. The expression of ERß mRNA was not affected by daidzein but was inhibited by E2. ERα protein was not detected while ERß protein was found in the nuclei of the cells. Daidzein and E2 upregulated the expression of ERß protein in the cells. In summary, the phytoestrogen daidzein directly affected the porcine ovary by inhibiting progesterone production and increasing ERß protein expression. Daidzein-induced changes in follicular steroidogenesis and granulosal sensitivity to oestrogens may disturb reproductive processes in pigs.

Expression of progesterone receptor membrane component 1, serpine mRNA binding protein 1 and nuclear progesterone receptor isoforms A and B in the bovine myometrium during the estrous cycle and early pregnancy.

The aim of this study was to investigate the (1) expression of progesterone membrane component 1 (PGRMC1), serpine mRNA binding protein 1 (SERBP1) and progesterone receptor (PR) mRNA and (2) protein expression levels of PGRMC1, SERBP1 and PR isoforms A and B in the bovine myometrium during the estrous cycle and early pregnancy. Uteri from cows on days 1-5, 6-10, 11-16 and 17-21 of the estrous cycle and weeks 3-5, 6-8 and 9-12 of pregnancy were used (n=5-6 per period). There were no changes (P>0.05) in PGRMC1 mRNA expression during the estrous cycle, while expression of SERBP1 and PR mRNA was the lowest (P<0.05) on days 11-16 relative to other days of the cycle. The highest mRNA expression of PGRMC1, SERBP1 and PR was found during pregnancy. There were no changes (P>0.05) in SERBP1 protein expression in cycling and pregnant cows, while the highest (P<0.05) PGRMC1 protein expression was found during weeks 3-5 of pregnancy. Similar protein expression profiles for PRA and PRB were found, and protein levels were highest on days 1-5 of the estrous cycle. From day 6 of the cycle, PRA and PRB protein expression decreased and were maintained at this lower level during pregnancy. In conclusion, our study assessed mRNA and protein expression levels of PGRMC1, SERBP1 and PR in the bovine myometrium during the estrous cycle and the first trimester of pregnancy. It is possible that progesterone (P4) affects myometrial function in a genomic and nongenomic manner.

The effect of ovarian steroids on oxytocin-stimulated secretion and synthesis of prostaglandins in bovine myometrial cells.

The aim was to study whether bovine myometrial cells have an enzymatic system able to produce prostaglandins (PGs) and whether PGs synthesis is regulated by steroids in a similar manner as endometrial cells. In Experiment 1, immunohistochemical studies localized proteins for cyclooxygenase 2 (COX2), PGE synthase (PGES) and PGF2alpha synthase (PGFS) in myometrial and endometrial (as positive control) slices from days 14 to 16 of the estrous cycle. Enzymatically isolated myometrial cells (2.5 x 10(5)/ml) were cultured for 96 h to attach them to the bottom of the culture well. In Experiment 2, cells were preincubated for 30 min with progesterone (P4; 10(-5) M), and thereafter incubated for 4 or 6h with arachidonic acid (AA; 10(-5) M, as positive control), oxytocin (OT; 10(-7) M), and OT+P4. In medium, PGE and PGFM (PGF2alpha metabolite) were increased (P<0.05) by AA treatment after 4 and 6h, but by OT only after 6h of incubation. Progesterone did not affect (P>0.05) basal secretion of both PGs, but it diminished (P<0.05) the stimulatory effect of OT on PGF2alpha and PGE secretion after 6h of incubation. The amount of enzyme protein for COX2, PGES and PGFS analyzed by Western Blot was affected (P>0.05) by any of the factors added to the culture medium. In Experiment 3, myometrial cells were preincubated with P4 (10(-5)M) and pregnenolone (P5; 10(-5)M) for 30 min, and then incubated for 6h with OT (10(-7) M) and OT plus each of these steroids used. Expression of mRNA for COX2, but not PGFS and PGES, was found in the cells stimulated with OT. Neither P4 nor P5 affected expression of the studied genes; however, both steroids diminished (P<0.05) OT-stimulated mRNA expression of COX2. The data suggest that: (a) myometrial cells are able to synthesize both PGF2alpha and PGE and (b) synthesis of these PGs may be regulated by steroids through a transcription-independent manner, which modulated the effect of OT on COX2 mRNA expression.