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Abstract: Polychlorinated biphenyls (PCBs), DDT and its metabolite (DDE) belong to estrogen-like endocrine disruptors. However, though their activity is approximately 1000-fold lower than the activity of estradiol (E2), this steroid's high concentration in follicular fluid and incubation media does not inhibit the influence of these xenobiotics. It was hypothesized that these xenobiotics might affect Steroidogenic Factor-1 (SF-1) and impair ovary function. To test this hypothesis, granulosa cells were obtained from ovarian follicles >1 or <1cm in diameter, which were treated with PCB-77, PCB-153, DDT or DDE (each at 10ng/ml), alone or jointly with an SF-1 antagonist (F0160). Treatment with the SF-1 antagonist inhibited (P <0.05) the secretion of P4 from cells of both sizes of follicles, as induced (P <0.05) by an SF-1 activator (HxP), DDE or PCB-153. All xenobiotics and HxP stimulated (P <0.05) the synthesis and secretion of oxytocin (OT). However, the effect on mRNA expression for NP-I/OT, which is OT precursor, was inhibited (P <0.05) by F0160 in all cultures treated with PCB-77, except for granulosa cells derived from follicles <1cm. Moreover, F0160 inhibited the effect on OT secretion of HxP, as well as all xenobiotics except for PCB-77 and DDE, in granulosa cells derived from follicles <1cm. Xenobiotic treatment did not affect (P >0.05) the expression for SF-1 mRNA. It is suggested that the SF-1 receptor may be involved in the adverse effects of xenobiotics on P4 secretion as well as the synthesis and secretion of OT. [Copyright &y& Elsevier]

Abstract: The orphan receptor Steroidogenic Factor-1 (SF-1, NR5A1), a member of the nuclear receptor superfamily, is present in fetal and adult steroidogenic tissues and also participates in the regulation of ovarian function. In this study, the expression levels of SF-1 mRNA and protein were determined in granulosa cells (from follicles >1cm and <1cm in diameter) and luteal tissue (from days 1–5, 6–10, 11–15, and 16–19 of the estrous cycle and weeks 3–5, 6–8, and 9–12 of pregnancy). Additionally, the effects of a synthetic SF-1 stimulator (4-(heptyloxy)phenol – HxP; 1×10−7 M) and a synthetic SF-1 inhibitor (F0160; 1×10−5 M) on the secretion of estradiol and oxytocin (OT) from granulosa cells (from follicles>1cm) and the secretion of progesterone (P4) and OT from luteal cells (days 11–16 of the estrous cycle) were investigated. The levels of SF-1 mRNA and protein were higher in granulosa cells (P <0.05) from follicles>1cm than in cells from follicles<1cm. In luteal tissue, the mRNA abundance was the highest (P <0.05) on days 6–10 of the estrous cycle, and the amount of protein was the highest on days 6–15 (P <0.05). The lowest levels of mRNA and protein for SF-1 were observed on days 16–19 of the estrous cycle (P <0.05). The abundance of SF-1 mRNA decreased at 9–12 weeks of pregnancy (P <0.05). The stimulation of the studied cells with HxP increased P4 and estradiol secretion from luteal and granulosa cells, respectively, and OT secretion from both types of cells. The SF-1 inhibitor did not affect hormone secretion by either type of cell, but it did diminish the effect induced by the SF-1 stimulator. The obtained data revealed estrous cycle-dependent levels of mRNA and protein for SF-1 in luteal tissue, and the use of a specific SF-1 stimulator and a specific SF-1 inhibitor confirmed the involvement of this receptor in steroidogenesis and OT secretion from cultured granulosa and luteal cells. These findings suggest that the SF-1 receptor participates in the local regulation of ovarian function during both the estrous cycle and the first trimester of pregnancy in cows. Furthermore, the concentrations of the SF-1 inhibitor and stimulator that we used in the primary cell culture could effectively modify the activity of this receptor. [Copyright &y& Elsevier]

The current investigations were undertaken to study the mechanism of the adverse effect of phytoestrogens on the function of bovine granulosa (follicles >1< cm in diameter) and luteal cells from day 1-5, 6-10, 11-15, 16-19 of the oestrous cycle. The cells were incubated with genistein, daidzein or coumestrol (each at the dose of 1 × 10 ). The viability and secretion of estradiol (E2), progesterone (P4) and oxytocin (OT) were measured after 72 h of incubation. Moreover, the expression of mRNA for neurophysin-I/OT (NP-I/OT; precursor of OT) and peptidyl-glycine-α-amidating monooxygenase (PGA, an enzyme responsible for post-translational OT synthesis) was determined after 8 h of treatment. None of the phytoestrogens used affected the viability of cells except for coumestrol. The increased secretion of E2 and P4 was only obtained by coumestrol (p < 0.05) from granulosa cells from follicles <1 cm in diameter and decreased from luteal cells on days 11-15 of the oestrous cycle, respectively. All three phytoestrogens stimulated (p < 0.05) OT secretion from granulosa and luteal cells in all stages of the oestrous cycle and the expression of NP-I/OT mRNA in the both types of cells. The expression of mRNA for PGA was stimulated (p < 0.05) by daidzein and coumestrol in granulosa cells, and by genistein and coumestrol in luteal cells. In conclusion, our results demonstrate that these phytoestrogens can impair the ovary function in cattle by adversely affecting the synthesis of OT in follicles and in corpus luteum. However, their influence on the ovarian steroids secretion was less evident. [ABSTRACT FROM AUTHOR]

• The effect xenobiotics (DDT, DDE, aldrine and dieldrine) on the secretory activity of smooth chorion slices was tested. • The synthesis and release of prostaglandin F2α, E2, oxytocin, progesterone, and estradiol and was studied. • The expression of enzymes participate in synthesis of these hormones was determined. • Used xenobiotics unfavorably affect the releasing studied hormones from smooth chorion. Chlorooganic xenobiotics (XBs) such as DDT, DDE, aldrin and dieldrin interfere with release of hormones from chorionic villi that are necessary for sustaining the normal course pregnancy: prostaglandins (PGs), oxytocin (OT), progesterone (P 4) and estradiol (E 2). Approximately 20 %–40 % of these hormones originate from the smooth chorion. The aim of current studies was to investigate effects of these XBs on synthesis and release of PGE 2 , PGF 2α , OT, P 4 and E 2 from explants of smooth chorion of cattle, obtained during the120–150 and 151–180 day gestational period. Explants were incubated with DDT, DDE, aldrin or dieldrin at concentrations of 1 and 10 ng/mL for 24 h, and concentrations of PGE 2 , PGF 2α , OT, P 4 and E 2 in post incubation medium and the relative abundances of COX-2, PTGES, AKR1B1, NP-I/OT, PAM, HSD3B, and CYP19A1 mRNA transcripts in tissue explants were determined. The XBs did not have effects on cell viability in explants (P > 0.05), however, there were effects on prostaglandins, OT and P 4 secretion and relative abundance of mRNA transcript for genes encoding the main enzymes involved in synthesis of these hormones (P < 0.05). The XBs that were evaluated did not have effects on E 2 synthesis and secretion (P > 0.05). In summary, XBs evaluated in the present study had effects on the pattern of prostaglandin secretion, and can increase OT and P 4 release from smooth chorion explants. Because XBs inhibit hormonal action throughout the chorion, there is an increase in risk of abortions or premature births in animals. [ABSTRACT FROM AUTHOR]

The role of prostaglandin E2 (PGE2) in basal and noradrenaline (NA)-stimulated utilization of high density lipoprotein (HDL) as a source of cholesterol for progesterone synthesis was examined. In Experiment 1, a cannula was inserted into the aorta abdominalis through the coccygeal artery (cranial to the origin of the ovarian artery) in mature heifers, to facilitate infusion of NA (4 mg/30 min; n=3) on day 10 of the estrous cycle. Three other heifers were similarly cannulated to serve as control. Before, during, and after NA or saline infusion, blood samples from the vena cava were collected every 5–15 min for analysis of PGE2, progesterone, and cholesterol. Each NA infusion stimulated (P<0.01) secretion of both hormones in heifers. Short-duration increases (P<0.05) in progesterone were observed due to the infusion of NA while cholesterol was not altered significantly. In addition, increases in PGE2 concentrations (P<0.05) compared to controls were seen after NA infusion. Therefore, we used an in vitro model to verify the effect of PGE2 on HDL utilization by luteal cells from day 5 to 10 of the estrous cycle. In the preliminary experiment, 10−6 M of PGE2 out of four different doses examined was selected for further studies, since it evoked the highest release of progesterone. In the next experiment, it was found that HDL increases progesterone secretion by luteal cells and both PGE2 and LH increased (P<0.05) the response to HDL while NA did not. In the last in vitro experiment, progesterone stimulated PGE2 secretion by luteal cells.In conclusion, PGE2 may be directly involved in the utilization of cholesterol from HDL for progesterone synthesis. Furthermore, PGE2 may influence NA-stimulated progesterone secretion by the corpus luteum (CL). It is concluded that there is a positive feedback loop between progesterone and luteal PGE2 during days 5–10 of the estrous cycle. [Copyright &y& Elsevier]