The inhibition of myometrial contractions by chlorinated herbicides (atrazine and linuron), and their disruptive effect on the secretory functions of uterine and ovarian cells in cow, in vitro.

The effect of atrazine and linuron, the popular and widely used chlorinated herbicides, on both myometrial contractions and secretory functions of bovine uterus and ovaries in vitro, was investigated. The pesticides inhibited (P<0.05) the basal and oxytocin (OT)-stimulated myometrial strips contractions, as well as the effect of OT on secretion of prostaglandins (PGs: PGF2α and PGE2) from endometrium. But only linuron inhibits the effect of OT on myometrial contractions. Neither of herbicides affected PGs secretion from myometrium and PGF2α from endometrium. Only the lowest dose of both tested compounds decreased PGE2 secretion from endometrium. The pesticides increased (P<0.05) the OT secretion from granulosa. However, only linuron stimulated (P<0.05) the OT secretion from the luteal cells, and it increased (P<0.05) the expression of mRNA for the OT precursor. Both compounds stimulated (P<0.05) the secretion of testosterone and atrazine increased (P<0.05) also the secretion of estradiol from the granulosa cells. While atrazine and linuron reduced (P<0.05) the progesterone secretion from the luteal cells. The data show that atrazine and linuron altered the secretory functions of ovarian cells and inhibited the myometrial contractions in vitro.

The adverse effects of aldrin and dieldrin on both myometrial contractions and the secretory functions of bovine ovaries and uterus in vitro.

Aldrin and dieldrin are chloroorganic insecticides which are recognised as endocrine disruptors. The aim of the study was to investigate their effect on the secretory functions of the uterus and ovary and on myometrial contractions. Myometrial strips and uterine and ovarian cells from nonpregnant cows were incubated with the xenobiotics (0.1, 1 or 10 ng/ml) for 24 or 72 h. Next, their effect on viability of myometrial, endometrial, granulosa and luteal cells, myometrial strip contractions, the synthesis and secretion of prostaglandins (PGs: PGF2α and PGE2) from uterine cells, the secretion of oestradiol (E2), testosterone (T) and oxytocin (OT) from granulosa cells and the secretion of progesterone (P4) and OT from luteal cells were determined. Neither of the xenobiotics (10 ng/ml) affected (P>0.05) the viability of the ovarian and uterine cells, while both (0.1-10 ng/ml) decreased (P<0.05) the basal and OT-stimulated myometrial contractions. In spite of these effects, neither of the insecticides affected (P>0.05) the synthesis and the secretion of PGs from the myometrial cells. Although they also did not impair the secretion of the PGs from the endometrial cells, they abolished (P<0.05) the stimulatory effect of OT (P<0.05) on the secretion of the PGs and stimulated (P<0.05) the secretion of OT from the granulosa and luteal cells. Moreover, aldrin and dieldrin stimulated secretion of E2 and T from the granulosa cells, while only dieldrin increased (P<0.05) the secretion of P4 from luteal cells. The data show that aldrin and dieldrin stimulated the secretory function of the cultured granulosa and luteal cells and inhibited the myometrial contractions of cows in vitro, which may affect on natural parturition.

Impairment of uterine smooth muscle contractions and prostaglandin secretion from cattle myometrium and corpus luteum in vitro is influenced by DDT, DDE and HCH.

The aim of this study was to investigate the effect of dichlorodiphenyltrichloroethane(DDT), dichlorodiphenyldichloroethylene (DDE) and γ-hexachlorocyclohexane (HCH) (10 ng/ml) on myometrial motility and the secretory function of the myometrium and corpus luteum (CL) collected from cows on days 8-12 of the estrous cycle. All of the xenobiotics increased (P<0.05) myometrial contractility. Moreover, the xenobiotics stimulated the secretion of the following prostaglandins (PGs) from myometrial strips: PGF2α, PGE2 and PGI2. DDT and DDE also increased (P<0.05) the release of PGF2α from CL strips, and HCH had the same effect (P<0.05) on the secretion of PGE2 and PGI2. The studied xenobiotics did not affect (P>0.05) PG synthesis, but DDT and DDE increased the mRNA expression levels of leukemia inhibitor factor (LIF), which can stimulate PG production. In summary, the xenobiotics affected PG secretion from cow myometrium and CL, which may contribute to the mechanism of uterine contraction disturbance.

The effect of DDT and its metabolite (DDE) on prostaglandin secretion from epithelial cells and on contractions of the smooth muscle of the bovine oviduct in vitro.

The insecticide DDT and its metabolite (DDE), due to their lipolytic nature and resistance to biodegradation, are accumulated in the living tissues. In cows, DDT and DDE were found to affect prostaglandin (PG) secretion from the endometrium and contractions of the myometrium. In this study, the impact of both xenobiotics (0.1, 1, 10 or 100ng/ml) on the function of epithelial cells and muscle strips of bovine oviducts from 1 to 5day of the oestrous cycle was examined. Therefore the concentration of PGE2 and PGFM (a metabolite of PGF2α) in culture media, mRNA expression of genes involved in PGs synthesis in epithelial cells and the force and amplitude of strips contractions were measured after 2 and 24 or 48h of incubation. Neither DDT nor DDE affected the viability of cells after 48h (P>0.05). Both DDT and DDE increased the concentrations of PGFM in culture medium and secretion of PGE2 after only 2h of cell culture (P<0.05). Similar effects were seen for the influence of DDE on amount of PGFM after 48h, while DDT decreased secretion of PGE2 (P<0.05). DDT after 2h increased (P<0.05) mRNA expression of PGF2α synthase (PGFS), while both xenobiotics decreased (P<0.05) mRNA expression of cyclooxygenase-2 (COX-2) after 24h. DTT also increased the force of isthmus contractions after 2h, as did both xenobiotics after 48h (P<0.05). Moreover, after 2 and 48h, DDE stimulated the amplitude of contractions of the isthmus as well as the ampulla, (P<0.05). The effect of both compounds on oviduct contractions was diminished by indomethacin, which blocks PG synthesis. We conclude that oviductal secretion of prostaglandins is affected, by DDT and DDE. The influence of these xenobiotics on PGF2α and PGE2 secretion and ratio may be part of the mechanism by which both DDT and its metabolite disturb the contractions of oviductal muscle.

Effect of environmental pollutants on oxytocin synthesis and secretion from corpus luteum and on contractions of uterus from pregnant cows.

Chloro-organic compounds are persistent environmental pollutants and affect many reproductive processes. Oxytocin (OT) synthesized in luteal cells is a local regulator of ovarian activity and uterine contractions. Therefore the effect of xenobiotics on the OT prohormone synthesis, secretion of OT and progesterone (P4) from luteal cells and on myometrial contractions during early pregnancy in cows was investigated. Luteal cells and myometrial strips from a cow at early pregnancy were treated with polychlorinated biphenyl 77 (PCB 77), dichlorodiphenyltrichloroethane (DDT), dichlorodiphenyldichloroethylene (DDE) and hexachlorocyclohexane (HCH) (1 or 10 ng/ml). The mRNA expression of neurophysin-I/oxytocin (NP-I/OT) and peptidyl-glycine-alpha-amidating mono-oxygenase (PGA) and concentration of OT and P4 were determined by RT-PCR and EIA, respectively. Moreover, the effect of xenobiotics given with P4 (12 ng/ml) on the basal and OT (10(-7)M) stimulated contractions of myometrial strips was studied. Xenobiotics increased (P<0.05) OT secretion but DDE only stimulated P4 secretion. The ratio of P4 to OT in culture medium was decreased by all xenobiotics during 9-12 weeks of pregnancy. All xenobiotics, except HCH, increased (P<0.05) mRNA expression of NP-I/OT during all stages of pregnancy and all treatments decreased (P<0.05) expression of mRNA for PGA during 9-12 weeks of pregnancy. Myometrial strips were relaxed (P<0.01) after pre-incubation with P4, while each of the xenobiotics jointly with P4 increased (P<0.01) myometrial contractions. In conclusion, the xenobiotics used increased both expression of mRNA for genes involved in OT synthesis and secretion of OT from luteal cells. This decreases the ratio of P4 to OT and presumably, in this manner, the chloro-organic compounds can influence uterine contractions and enhance risk of abortions in pregnant females.

Influence of polychlorinated biphenyls and their hydroxylated metabolites on prostaglandins secretion from epithelial cells of bovine oviduct, in vitro.

Polychlorinated biphenyls (PCBs) markedly stimulate bovine uterine contractions and prostaglandin (PG) F2alpha secreted from both, myometrial and endometrial cells is essentially involved in this process. Since contractions of the oviduct are crucial for gametes and embryo transport, therefore the goal of this study was to investigate the influence of PCBs on PGF2alpha and PGE2 secretion from oviductal epithelium. Epithelial cells of the oviduct, from cows and heifers on days 1-5 of estrous cycle, were treated with PCBs: technical mixture (Aroclor 1248; Ar 1248), individual congeners (PCB 30 and PCB 153) and hydroxylated metabolites (PCB 30-OH and PCB 50-OH). Viability of the cells after treatment with PCBs (10 and 100 ng/ml) was determined after 24, 48 and 72 h. The concentration of PGFM (metabolite of PGF2alpha) and PGE2 in culture medium was determined after 2 and 48 h of incubation with PCBs (0.1, 1 and 10 ng/ml). None of the PCBs affected (P>0.05) cell viability, whereas all of them, except PCB 30 after 48 h of treatment, increased (P<0.05-0.01) PGF2alpha secretion from epithelial cells. All PCBs also stimulated (P<0.05) the PGE2 secretion after 2h of incubation, but this effect was less evident or there was no effect after 48 h of treatment. We conclude that oviductal secretion of PGF2alpha and PGE2 is affected by PCBs and this can be a part of the mechanism by means of which PCBs may affect the contractions of bovine oviduct.

Involvement of prostaglandin F2alpha in the adverse effect of PCB 77 on the force of contractions of bovine myometrium.

Polychlorinated biphenyls (PCBs) stimulate in vitro both the force of myometrial contractions and endometrial secretion of PGF2alpha in cattle. Therefore, the goal of this study was to investigate the participation of PGF2alpha in the effect of PCBs on uterine contractility. For this aim, the myometrial strips were incubated (48h) with PCB 77 at the dose of 1, 10 and 100ng/ml (i.e., 0.0034, 0.034 and 0.34nmol/ml) separately or jointly with indomethacin (INDO, 10(-4)M), which blocks the PGF2alpha synthesis. Next, the force of myometrial strips contractions was measured. Further, the influence of PCB 77 (0.1, 1 and 10ng/ml) on the PGF2alpha secretion from myometrial cells after 6, 24, and 48h and PCB 77 (1 and 10ng/ml) on the mRNA expression of cyclooxygenase 2 (COX-2) and PGF2alpha synthase (PGFS) in myometrial cells after 6 and 24h, was investigated. The increase (P<0.05-0.001) of the contractions force of myometrial strips evoked by each dose of PCB 77, was markedly reduced (P<0.05-001) by INDO. There was an increase (P<0.05-0.001) of both PGF2alpha secretion after all studied periods of cell incubation and mRNA expression for COX-2 and PGFS after 6h treatment of myometrial cells with PCB 77. It can be concluded that myometrial synthesis of PGF2alpha and its further secretion is a part of the mechanism by means of which PCB 77 may affect the force of myometrial contractions in cattle.

The influence of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and its metabolite-dichlorodiphenyldichloroethylene (DDE) on mRNA expression for NP-I/OT and PGA, involved in oxytocin synthesis in bovine granulosa and luteal cells.

The effect of polychlorinated biphenyls (PCBs) congeners (PCB 77, PCB 126, PCB 153) and their technical mixture-Aroclor (Ar) 1248, as well as dichlorodiphenyltrichloroethane (DDT) and its metabolite-dichlorodiphenyldichloroethylene (DDE; two individual isomers p,p'- and o,p'- or their mixture, 95% and 5%, respectively) at the dose of 10 ng/ml each, on the gene expression of (a) oxytocin (OT) precursor-neurophysin-oxytocin (NP-I/OT) and (b) peptidyl glycine-alpha-amidating mono-oxygenase (PGA), the terminal enzyme in the pathway of OT synthesis, was studied. Granulosa cells from follicles >1cm in diameter, collected on days 19-21 of estrous cycle, and luteal cells from corpora lutea (CL) collected on days 8-12 of the estrous cycle were used. The cells were incubated (6h) with these xenobiotics and the expression of NP-I/OT and PGA genes was determined. All PCBs increased (P<0.05) NP-I/OT gene expression in granulosa cells. Similarly, all PCBs but PCB 126 increased (P<0.05) PGA gene expression in these cells. DDT and DDE increased (P<0.05) gene expression of NP-I/OT in granulosa cells, while gene expression of PGA in these cells was stimulated (P<0.05) by DDE only. The mRNA expression for NP-I/OT and PGA in luteal cells was increased (P<0.05) by PCB 77 and PCB 153. Both DDE isomers and mixture also stimulated (P<0.05) of NP-I/OT mRNA expression, while increase (P<0.05) of PGA mRNA expression was elicited by incubation of these cells with DDE mixture and Ar 1248. Obtained data suggest that PCBs, DDT and DDE can affect the mRNA expression for NP-I/OT and PGA in bovine granulosa and luteal cells.