Effects of commonly used carbamates (carbaryl and thiram) on the regulatory, secretory and motor functions of bovine cervixes in vitro.

Previously studied classes of pesticides, including organochlorines, organophosphates and pyrethroids disturb the mechanism that causes bovine myometrial contractions. Hence, the aim of this study was to investigate the effects of carbaryl and thiram, which are representative carbamate pesticides commonly used in global agriculture, on the motor and secretory functions of bovine cervixes. Additionally, the impacts of these pesticides on intra- and intercellular signaling in vitro were estimated. In this study, cervical cells or strips were obtained from cows at days 18-20 of the estrous cycle and were treated with carbaryl or thiram. Neither carbamate (10 or 100 ng/ml) exerted cytotoxic effects. Carbaryl increased the level of mRNA (at a dose of 0.1 ng/ml) and protein (at both doses, 1 and 10 ng/ml) expression for the oxytocin receptor (OXTR), while thiram (at 0.1 and 10 ng/ml or 0.1-10 ng/ml, respectively) caused the opposite effects. Moreover, the level of the second messenger inositol-trisphosphate (IP3) was decreased by carbaryl (10 ng/ml) but increased by thiram (10 ng/ml). Only thiram decreased prostaglandin-endoperoxide synthase 2 (PTGS2; 0.1 ng/ml) and aldo-keto reductase family 1, member B1 (AKR1B1; 0.1 ng/ml), and prostaglandin E synthase 2 (PTGES2; 0.1-10 ng/ml) mRNA expression, while thiram (0.1-10 ng/ml) and carbaryl (0.1 and 10 ng/ml) both decreased the release of PGF2α. Carbaryl (10 ng/ml) and thiram (10 ng/ml) also decreased the level of a gap junction protein (GAP). Moreover, carbaryl (10 ng/ml) decreased the level of myosin light chain kinase (MLCK). However, the strength of cervical contractions was increased by thiram (1 and 10 ng/ml) but decreased by carbaryl (1 and 10 ng/ml). Carbaryl increased the receptivity of cervical cells to oxytocin (OXT), but inhibited further transduction (IP3) of this signal. Hence, direct inhibition of cervical strip contraction may occur. In contrast, thiram mostly decreased the receptivity of cervical cells to OXT, while it stimulated the contraction of cervical strips. Moreover, compared to carbaryl, thiram more greatly affected the synthesis and release of prostaglandins. These results suggest that carbaryl and thiram disturb OXT signaling, PG secretion and cervical contraction in vitro.

Luteotropic and Luteolytic Factors Modulate the Expression of Nuclear Receptor Coregulators in Bovine Luteal Cells Independently of Histone Acetyltransferase and Histone Deacetylase Activities.

The aims of this study were to examine the effect of luteotropic and luteolytic factors on the mRNA and protein expression of the coactivators HAT: histone acetyltransferase p300 (P300), cyclic adenosine monophosphate response element-binding protein (CREB), and steroid receptor coactivator-1 (SRC-1) and the corepressor: nuclear receptor corepressor-2 (NCOR-2) in bovine luteal cells on days 6-10 and 16-20. HAT and HDAC activities were also measured. The obtained results showed that luteotropic and luteolytic factors influence changes in the mRNA and protein levels of the coregulators of PGRs. However, they did not affect the activity of related HAT and HDAC, respectively. Therefore, it is possible that these factors, through changes in the expression of nuclear receptor coactivators and corepressors, may affect the functioning of the nuclear receptors, including PGRs, in the bovine CL.

Do cypermethrin and fenvalerate disturb the function of the bovine cervix in vitro?

This study aimed to investigate the effect of pyrethroid insecticides on the regulation of bovine cervical function. Cervical cells or strips obtained from cows during the periovulation period were treated with cypermethrin and fenvalerate (0.1-10 ng/mL). None of the pyrethroids exerted a cytotoxic effect, whereas only fenvalerate increased the cervical contraction force and mRNA expression of receptor of oxytocin and prostaglandin (PG) synthases. Both pyrethroids inhibited PG secretion and decreased the amount of diacylglycerol, which is the second messenger involved in oxytocin signal transmission, and fenvalerate decreased the myosin light-chain kinase level. These findings indicate that fenvalerate induces greater disruption of cervical function than cypermethrin.

Do commonly used herbicides (atrazine and glyphosate) have the potential to impair the contractions, prostaglandin releasing and conducting of oxytocin signal at the bovine cervix in vitro?

Glyphosate (Gly) and atrazine (Atr) are among the most commonly used herbicides in global agriculture. It was previously shown that both Atr and Gly impair the ovarian and uterine secretion of regulators of myometrial motility (oxytocin (OT) or prostaglandins (PGs)) in cows, and Atr can also decrease the force of contractions in strips from the uterine horn. Hence, the aim of this study was to compare the effects of Atr and Gly on the motor and secretory function of the bovine cervix in vitro as well as receptivity and signal transduction in cervical cell cultures. Cervical strips or cells obtained from cows before ovulation were treated with environmental doses of Atr or Gly (0.1-10 ng/ml) since these herbicides exerted no cytotoxic effect at a dose of 100 ng/ml. Only Atr increased the force of cervical contractions, while both Atr and Gly decreased the secretion of prostaglandins (PGs) without disturbing their synthesis. Moreover, Atr decreased the mRNA expression and protein level of oxytocin receptor (OTR), while Gly increased OTR protein levels. Both Atr and Gly decreased the contents of gap junction proteins (GAPs), Atr decreased the contents of second messengers (diacylglycerol - DAG, inositol-tris-phosphate - IP3), and Gly decreased the level of myosin light chain kinase (MLCK) but increased DAG levels. Atr directly enhanced the cervical strips contractions. Both herbicides disturbed cellular signalling and inhibited PGs secretion. It suggest that Atr and Gly have the potential to impair the activity of cervical cells in vitro, which might be followed by failure of maintenance with gestation.

The effect of polychlorinated biphenyls (PCBs) on bovine oviductal contractions and LIF synthesis during estrous cycle, in vitro studies.

Polychlorinated biphenyls (PCBs) are a group of synthetic xenobiotics that have been used in many industrial applications. Currently, PCBs are among the most prominent environmental contaminants. Previously we showed that PCBs impair secretion of prostaglandins (PGs) at the oviduct. PGs are involved in the regulation of oviductal contractions and the synthesis of leukemia inhibitory factors LIF. Since oviductal contractions are crucial for gamete and embryo transport, and LIF is essential for embryo implantation, the direct effect of PCBs on oviductal motor activity and LIF mRNA expression were investigated. Oviductal strips and cells were taken from cows during the estrous cycle and were treated with PCBs at concentrations close to their environmental ranges. All the studied PCBs decreased the force of the contractions of the longitudinal and circular muscles of the isthmus. Additionally, these PCBs decreased the amplitude of the longitudinal muscle of the oviduct. Moreover, PCB-30-OH and PCB-153 increased the mRNA expression of LIF. Since PCBs inhibit the motor function of the oviduct and stimulate the synthesis of LIF, it is possible that PCBs can slow gamete or embryo transport and increase the potential for pathological embryo implantation in the oviduct.

Do chlorinated insecticides (aldrin and DDT) or products of their transformations (dieldrin and DDE) impair signal transfer from regulators (oxytocin and relaxin) of bovine myometrium motility in vitro?

Aldrin, dieldrin, and DDT are chlorinated insecticides that are unintentionally widespread in the environment. It was previously shown that all of the aforementioned compounds increased secretion of ovarian oxytocin (OT), which is a potent uterotonic agent. However, only DDT and its metabolite (DDE) promoted, while aldrin and dieldrin inhibited basal and OT-stimulated myometrial contractions in cows. Therefore, the aim of this study was to determine the effect of these treatments on the reception and further transmission of the OT-signal for myometrial contractions and on the levels of contractile-associated integral proteins (caveolin; CAV) and gap junction proteins (GAPs). Moreover, their effect on reception of signal for the relaxation of myometrium was also studied. Myometrial strips or cells from non-pregnant (8-12 days of oestrous cycle) or late pregnant (5-8 months) cows were incubated with the studied compounds at environmentally relevant dose (10 ng/ml), which was chosen according to the previous studies. DDT and DDE increased the CAV protein level, while dieldrin decreased the GAPs level. None of the studied compounds affected mRNA expression of the OT receptor and expression of the second messengers (DAG, IP3, PKC, MLCK). Oppositely, DDE and dieldrin decreased mRNA expression of the relaxin (RLX) receptor. Changes in the amount of contractile-associated integral proteins may be involved in the molecular mechanism underlying the adverse effects of the studied insecticides on myometrial motility. Admittedly, none of the studied compounds impaired the reception or further intracellular transmission of the OT signal to promote contractions during the oestrous cycle, while they showed potential to impair the transmission the signal between cells as well as to diminish the effects of one of the primary inhibitor (RLX) of myometrial contractions during gestation.