Influence of prostaglandins on the spontaneous motility of pig oviducts

The effects of prostaglandins (PG) F_2α and E₂ on the spontaneous motility of pig oviducts were studied in vivo and in vitro using intraluminal pressure transducers. PGF_2α always increased the muscular activity of the oviducts, gradually augmenting their sensitivity to PGF_2α stimulation from pro-oestrus, reaching their highest responsiveness at the peri-ovulatory stage, and decreasing thereafter. PGE₂ elicited inhibitory responses from the tubal preparations during oestrus and the third day of the cycle in vivo, and during pro-oestrus and oestrus in vitro. The isthmic longitudinal muscle layer was always contracted by the exogenous PGE₂ in vitro. During the luteal phase, PGE₂ elicited a stimulatory response both in vivo and in vitro, of a similar type of that of the PGF_2α. These stimulatory responses could be blunted, but not abolished, by selective blocking of α-adrenoceptors in vitro. Indomethacin inhibited in a concentration-dependent manner the spontaneous motility of the pig oviducts in vitro. This inhibition was reversible and the spontaneous motility could be fully restored after total abolition of activity by addition of PGF_2α, but not of noradrenaline, which only increased the tonus of the inhibited preparations.     

Effect of chronic alcohol consumption on rat uterine spontaneous motility, prostaglandin production and triglyceride metabolism

The spontaneous isometric developed tension (IDT), the synthesis and release of prostaglandins (PGs) into the incubating medium and the metabolism of triglycerides (TGs) in uterine strips isolated from controls and chronic ethanol fed rats, were studied. In order to observe how the uterus of rats fed alcohol reacts during a situation of metabolic emergency, the above mentioned studies were done in the presence or in the absence of glucose in the incubating medium. The decrement of IDT as time progressed was significantly greater in strips obtained from rats which had been drinking 20% ETOH than in controls. Nevertheless, the absolute magnitude of the initial IDT was similar in both groups. On the other hand, the decline of the frequency of contractions (FC) of uterine strips isolated from controls and from ETOH-exposed rats, after 60 min of spontaneous activity was similar. When the uterine strips isolated from ETOH-exposed and from control rats were suspended in glucose-free solution they exhibited the same decrement of IDT and FC after 60 min of activity. The basal release of PGE1 and PGE2 was similar in control tissues incubated in medium containing glucose, but the output of PGE2 was significantly smaller than that of PGE1 in uterine strips isolated from ETOH-exposed rats. The production of PGE1 and PGE2 by uteri suspended in glucose-free medium was similar in control preparations. On the contrary the release of both PGs differs in uterine strips from ETOH-exposed rats, i.e. the output of PGE2 was significantly smaller than in controls and the release of PGE1 increased around 4-fold in comparison with controls.(ABSTRACT TRUNCATED AT 250 WORDS)     

Is the spontaneous motility of isolated rat uterus controlled by prostaglandin E?

Variations in the spontaneous contractile activity during 6 hours following isolation of uterine horns from proestrus, metestrus and spayed rats, were explored. In estrus and metestrus preparations the contractions declined during 60 min and between 180--200 min a progressive spontaneous recovery (abolished by indomethacin) was observed up to 360 min. Uteri from proestrus and spayed animals exhibited a continuous depression without recovery during the whole experimental period. At 60 min, uterine horns from estrus animals (which showed a marked contractile decrement) released to the suspending medium significantly less prostaglandin E-like material than at 360 min, i.e. when contractions had almost completely recovered. No modification in the amount of prostaglandin F-like material was detected accompanying these spontaneous contractile variations. In the spayed group at 60 min of functioning (i.e. when the contractile impairment was significantly smaller than at a later time) the release of PGE was greater than at 360 min. These findings suggest a possible control of rat uterine contractions by PGE, rather than by PGF.     

Is the spontaneous motility of isolated rat uterus controlled by prostaglandin E?

Variations in the spontaneous contractile activity during 6 hours following isolation of uterine horns from proestrus, metestrus and spayed rats, were explored. In estrus and metestrus preparations the contractions declined during 60 min and between 180–200 min a progressive spontaneous recovery (abolished by indomethacin) was observed up to 360 min. Uteri from proestrus and spayed animals exhibited a continuous depression without recovery during the whole experimental period. At 60 min, uterine horns from estrus animals (which showed a marked contractile decrement) released to the suspending medium significantly less prostaglandin E-like material than at 360 min, i.e. when contractions had almost completely recovered. No modification in the amount of prostaglandin F-like material was detected accompanying these spontaneous contractile variations. In the spayed group at 60 min of functioning (i.e. when the contractile impairment was significantly smaller than at a later time) the release of PGE was greater than at 360 min. These findings suggest a possible control of rat uterine contractions by PGE, rather than by PGF.     

Acute effects of a single ethanol injection on in vitro rat uterine spontaneous motility, on uteri prostaglandin production and on tissue metabolism of triglycerides.

The acute effects of ethanol (ETOH), injected at 3 g.kg-1i.p. on spontaneous contractions, on prostaglandin (PG) production and on the metabolism of triglycerides (TGs), have been studied in uterine strips obtained from rats at diestrus and suspended in glucose-containing or glucose-free solution. The absolute values of isometric developed tension (IDT: expressed in mg) recorded at 0 time (initial or post isolation determinations) and the frequency of contraction (FC), expressed as the number of contraction cycles during 20 min, were similar for uterine strips from controls and from ETOH treated rats. The uterine IDT and the FC expressed as percent changes from internal controls (0 time values) were explored during 180 min in uteri suspended in glucose medium. The magnitude of IDT decreased, as time progressed, both in controls as well as in ETOH-treated rats. Afterwards, uterine strips from controls exhibited a partial recovery of their contractile activity. This pattern of recovery was not observed in uterine strips from ETOH-treated rats. The uterine IDT, in the ETOH-injected animals after 180 min of activity, were significantly smaller than those of controls. On the other hand, the FC decreased progressively up to the end of the experimental period both in controls as well as in ETOH-treated rats. In glucose-free medium, the IDT of uterine strips from ETOH-injected animals diminished significantly more than controls from 100-180 min following isolation and mounting. In addition, the FC of uterine strips from the ETOH group of rats were significantly smaller than in controls suspended in glucose-free solution.(ABSTRACT TRUNCATED AT 250 WORDS)     

Sow (Sus scrofa) follicular fluid: prostaglandin content and effect on the motility of isolated oviducts

The present study provides information regarding the effects of the sow follicular fluid (FF) on the motility of isolated segments of swine and rabbit oviducts. In addition, the concentration of prostaglandins (PGs) F2 alpha, E2 and E1 in the follicular fluid of sow ovaries isolated at different stages of the sex cycle as well as the generation of the same PGs by walls of ovarian follicles in early and late proestrus, in estrus, in metestrus and in diestrus, were explored. The stimulatory contractile effect of proestrous FF in isolated segments of sow fimbria was antagonized by polyphloretin phosphate (PPP), a PG receptor blocker and by indomethacin, an inhibitor of PG synthesis. The positive inotropism evoked by the FF was mimiked by bradykinin and the influences of both interventions were similarly antagonized by PPP. It appears plausible that the inotropic effect of the preovulatory FF on the sow fimbria could be not only by PGs already present in the fluid, but also by the stimulation of the synthesis of tubal PGs by follicular fluid bradykinin. The FF also stimulated the ampullary tubal segments isolated from proestrous sows whereas the same volume of FF depressed significantly the isometric developed tension of rabbit ampulla. The total concentration of the three PGs in the FF from late proestrous follicles was significantly greater than that of the same PGs in the other two stages of the sex cycle (early proestrus and diestrus), whereas the concentration of each PG (PGE2, PGF2 alpha or PGE1), did not differ within any of the stages of the cycle. Furthermore, the total amount of the three PGs produced by the walls of follicles from late proestrous ovaries was also significantly greater than that generated by ovarian follicles from early proestrus, estrus, metestrus and diestrus. In summary the results document that the concentration of each one of the PGs measured (E2, E1 or F2 alpha) attained maximal values at the time of ovulation. The results regarding the effects of FF on the inotropic activity of fimbrial and ampullary segments of sow oviducts also suggest that the fluid might play a physiological role, favouring the capture and transfer of ova into the oviducts at the moment of ovulation.     

The effect of estradiol on isolated rat uterine motility and on prostaglandin generation

The motility of isolated uterine horns as well as the generation of PGE and PGF like material by the uterus from estrus and spayed rats, treated or untreated with 17-beta estradicl, were studied. Following 40 minutes of mounting the spontaneous motility of uteri from estrus rats had a lower magnitude than that from spayed ones. The amount of PGF-like material was similar in both groups whereas the first one liberated less PGE-like substance. In spayed animals treated with 1 μg of 17-beta estradiol the decay of spontaneous contractile force was higher than that observed in untreated rats, and similar to that displayed by uteri from estrus. Less PGE-like material was liberated in comparison with spayed animals and a tendency to produce higher quantity of PGF-like compounds was observed, although the level was not significantly different. With 50 μg of 17-beta estradiol the spontaneous reduction of contractile activity was higher than in spayed animals and than in those treated with 1 μg. The amount of PGF-like material liberated was higher than in spayed rats and less PGE-like substance was generated comparing with spayed and 1 μg-treated animals. These findings show that estradiol decreases the release of PGE-like compound. It would also appear that this may have some relationship with the levels of spontaneous contractile activity of the isolated rat uterus.     

Effect of progesterone on the spontaneous motility and prostaglandin synthesis in uterine horns isolated from ovariectomized rats

The motility of isolated uterine horns as well as the generation of PGE and PGF-like material by uterus from spayed rats, treated or untreated with progesterone or progesterone plus estradiol-17-beta, were studied. The changes of Functional Activity (FA) with time (constancy) of control uterine horns and that preparations treated wtih 2 mg of progesterone (P) were not significantly different. However, the PGF-like material released into the bathing solution was significantly higher when the animals were treated with P. PGE-like material in the medium was similar in both groups. With higher doses to P (4 mg/day/2 days) the constancy of FA was similar to that observed in untreated animals, and the PGF-like material released into the medium was significantly higher than in the control group FA and PGs releases into the bathing medium by uterine horns from supra-renalectomized-ovariectomized animals (treated or not with P) were similar to those obtained in spayed rats with the intact suprarenal gland, but the absolute values of PGF-like material were always lower than in this group. Estradiol-17-beta injected prior or after P diminished the stimulation induced by P on the release of PGF-like material into the medium. The constancy of the contractile activity as well as the uterine release of PGE-like material was also diminished in rats treated with P plus estradiol-17-beta. The novel finding that progesterone stimulates the synthesis of PGF in uterine horns from ovariectomized rats without changing that of PGE is discussed.     

Influence of ketamine on the spontaneous motility of chick embryos and its development.

The effects of acute and chronic application of ketamine on the resting spontaneous motility, its development and reactivity was studied in chick embryos of white Leghorns. 1. Acute application of ketamine (Narcamon) in a dose of 12.5 mg/kg e.w. partially depressed spontaneous motility as early as in 11-day old chick embryos. From day 15 of incubation ketamine very effectively blocked spontaneous motility. 2. Ketamine was fully ineffective in spinal preparations (decapitation on day 2 of incubation) of 11- and 13-day-old embryos. It was not until day 15 evoked that it depressed motility as in normal embryos. 3. Chronic continuous supply of ketamine (average dose 6.34 +/- 0.72 mg/kg e.w./24 h) from day 4 of incubation till day 8, 12, or 16 of incubation reduced the developmental decrease of spontaneous motility by 23.1-6.0% as compared to the controls. This effect was already observed after the first 4 days of chronic application of ketamine. 4. Chronic application of ketamine significantly diminished the strychnine activation and GABA-mediated depression of spontaneous motility. The depressive effect of the acute application of ketamine itself was hardly affected. The results have shown that ketamine interferes with the development of the endogenous rhythm of intrinsic activity and with the development of reactivity of the generator of embryonic spontaneous motility.     

Influence of oxygen concentration in the gas phase on cultures of mouse and rat ova]

Two cell mouse and rat embryos are cultivated in vitro in the conditions described by Whitten, reducing the oxygen concentration in the gaseous phase at 5%. The first ones can become blastocysts while the second ones are stopped in their development.     

Acetaminophen-sensitive prostaglandin production in rat cerebral endothelial cells

Acetaminophen is a widely used antipyretic and analgesic drug whose mechanism of action has recently been suggested to involve inhibitory effects on prostaglandin synthesis via a newly discovered cyclooxygenase variant (COX-3). Because COX-3 expression is high in cerebral endothelium, we investigated the effect of acetaminophen on the prostaglandin production of cultured rat cerebral endothelial cells (CECs). Acetaminophen dose-dependently inhibited both basal and LPS-induced PGE(2) production in CECs with IC(50) values of 15.5 and 6.9 microM, respectively. Acetaminophen also similarly inhibited the synthesis of 6-keto-PGF(1alpha) and thromboxane B(2). LPS stimulation increased the expression of COX-2 but not COX-1 or COX-3. In addition, the selective COX-2 inhibitor NS398 (1 microM) was equally as effective as acetaminophen in blocking LPS-induced PGE(2) production. Acetaminophen did not influence the expression of the three COX isoforms and the inducible nitric oxide synthase. In LPS-stimulated isolated cerebral microvessels, acetaminophen also significantly inhibited PGE(2) production. Our results show that prostaglandin production in CECs during basal and stimulated conditions is very sensitive to inhibition by acetaminophen and suggest that acetaminophen acts against COX-2 and not COX-1 or COX-3. Furthermore, our findings support a critical role for cerebral endothelium in the therapeutic actions of acetaminophen in the central nervous system.     

Endothelial cell confluence regulates cyclooxygenase-2 and prostaglandin E2 production that modulate motility

Endothelial cells line the vasculature and, after mechanical denudation during invasive procedures or cellular loss from natural causes, migrate to reestablish a confluent monolayer. We find confluent monolayers of human umbilical vein endothelial cells were quiescent and expressed low levels of cyclooxygenase-2, but expressed cyclooxygenase-2 at levels comparable with cytokine-stimulated cells when present in a subconfluent culture. Mechanically wounding endothelial cell monolayers stimulated rapid cyclooxygenase-2 expression that increased with the level of wounding. Cyclooxygenase-2 re-expression occurred throughout the culture, suggesting signaling from cells proximal to the wound to distal cells. Media from wounded monolayers stimulated cyclooxygenase-2 expression in confluent monolayers, which correlated with the level of wounding of the donor monolayer. Wounded monolayers and cells in subconfluent cultures secreted enhanced levels of prostaglandin (PG) E(2) that depended on cyclooxygenase-2 activity, and PGE(2) stimulated cyclooxygenase-2 expression in confluent endothelial cell monolayers. Cells from subconfluent monolayers migrated through filters more readily than those from confluent monolayers, and the cyclooxygenase-2-selective inhibitor NS-398 suppressed migration. Adding PGE(2) to NS-398-treated cells augmented migration. Endothelial cells also migrated into mechanically denuded areas of confluent monolayers, and this too was suppressed by NS-398. We conclude that endothelial cells not in contact with neighboring cells express cyclooxygenase-2 that results in enhanced release of PGE(2), and that this autocrine and paracrine loop enhances endothelial cell migration to cover denuded areas of the endothelium.     

Influence of the uterine environment on rat sperm motility and swimming speed

The present study compared several rat sperm parameters in semen samples recovered from a natural uterine environment (i.e., intact estrous female) to those recovered from an artificially induced uterine environment (i.e., ovariectomized hormonally primed female). The sperm parameters measured were percent motile, percent exhibiting forward progressive motility, actual swimming speed, and linear swimming speed. The comparisons were conducted at four postcopulatory time points (0.25, 1.5, 3, and 6 hours) in order to detect differences as a function of residence time within the uterus. No significant differences (P less than 0.05) in the parameters were seen between the two types of uterine environments. Residence time within the reproductive tract had no significant effect on the parameters with the exception of percent motile, which was significantly increased (P less than 0.01) at the 1.5-hour postcopulatory time point.     

Differential effects of ibuprofen and naproxen sodium on menstrual prostaglandin release and on prostaglandin production in the rat uterine homogenate

In two independent studies, ibuprofen and naproxen sodium were found to be equi-effective in alleviating dysmenorrheic symptoms. However, the effects of these drugs on menstrual PG release were found to be dissimilar. Ibuprofen primarily inhibited menstrual PGF_2α release with little effect on PGE release, whereas, naproxen sodium inhibited both PGF_2α and PGE₂ release equally. To verify these results, we determined the inhibitory potency, IC 50' of ibuprofen and naproxen sodium on PGF_2α and PGE₂ synthesis in the rat uterine homogenate system. The preferential PGF2a inhibitory activity of ibuprofen was confirmed.These findings suggest that ibuprofen may, in addition to inhibiting fatty acid cyclooxygenase, also inhibit PGF_2α reductase, or some other PG metabolic pathways which affect PGF a and PGE₂ synthesis differently. The significance of this differential PG synthesis inhibitory effect in dysmenorrheic therapy is discussed.     

Influence of thrombin on proliferation and prostaglandin production in cultured bovine endometrial cells

The control of cell proliferation by thrombin was studied in vitro in cultured epithelial and stromal cells of the endometrium. The effect of thrombin was studied after chronic treatment (72 hr) in medium containing 10% fetal bovine serum (FBS) combined or not with sex steroids. Thrombin inhibited slightly the proliferation (based on DNA measurements) only in epithelial cells (P < 0.05). 17β-estradiol (E) and progesterone (P4) had no mitogenic effects. The presence of functional thrombin receptors was estimated by stimulation of second messenger generation in response to increasing doses of thrombin (0-1,500 ng/ml). In confluent cultures of epithelial cells, the addition of thrombin for 10 min stimulated cAMP production by 50% with a maximal response at 500 ng/ml (P < 0.05). Similarly, in stromal cells, thrombin stimulated cAMP production in a dose-dependent manner (P < 0.01). Generation of inositol-phosphates was also stimulated by 50% in epithelial cells (P < 0.03), with a maximal response at 500 ng/ml, and by 45% in stromal cells (P < 0.01), with a maximal response at 50 ng/ml. The effect of thrombin on cell proliferation was investigated by ³H-thymidine incorporation in serum-free medium for 24 hr. Thrombin inhibited incorporation in epithelial cells (P < 0.0001) in a dose-dependent manner. Conversely, thrombin stimulated significantly incorporation of stromal cells (P < 0.05) at 50 ng/ml. The effect of sex steroids was also evaluated and it was found that E had no effect on cell proliferation, while P4 inhibited the incorporation in both epithelial (P < 0.001) and stromal cells (P < 0.001). The effect of a combined treatment with thrombin and E inhibited both epithelial (P < 0.001) and stromal cell (P < 0.001) growth, but a combination of thrombin and P4 had no additional effect on growth compared to P4 alone. Further investigation of the role of thrombin has been carried out by measuring prostaglandin (PG) responses. Addition of thrombin for 24 hr inhibited PGF_2α production by epithelial cells (P < 0.0001) but had no effect on PGE₂ production by stromal cells. Therefore, functional receptors for thrombin appear to be present in epithelial and stromal cells of the bovine endometrium. The minimal effect of thrombin alone or in combination with sex steroids on endometrial cell proliferation in vitro combined with the evidence of functional thrombin receptor in these cells, suggest that: (1) the effect of sex steroids in cultured endometrial cells is not modulated by the presence of thrombin, and (2) other factors are necessary for the full expression of mitogenic responses to sex steroids in vitro. © 1996 Wiley-Liss, Inc.     

Differential transport of embryos and degenerating ova by the oviducts of the long-tongued bat, Glossophaga soricina.

Female long-tongued bats which had been maintained in sexually segregated groups in captivity for more than 8 months were bred and killed at various intervals between Days 1 and 25 post coitum. Their reproductive tracts were then examined histologically. In 20 of the 28 bats carrying tubal embryos the remnants of 1-4 other ova were also observed in the oviductal ampullae. These remnants consisted of intact zonae pellucidae containing cellular debris, empty zonae, and/or zona fragments. Since long-tongued bats are monovular, the remnants had apparently been retained in the oviducts from previous, non-fertile reproductive cycles. In 27 of the 31 bats carrying implanting blastocysts, zonae pellucidae probably shed by the embryos had been retained in the oviducts. The remnants of 1-3 ova were also observed in the oviductal ampullae of 22 of the 31 bats carrying uterine blastocysts. In at least 14 of these bats the embryos had by-passed ovum remnants in the oviducts on their way to the uterus. No evidence of such remnants was found in the oviducts of 17 animals with tubal or uterine embryos, although old, as well as new, CL were present in the ovaries.     

Influence of angiotensins (I,II & III) on prostaglandin production by minced rat renal medulla

Minced rat renal medulla was incubated for 30 min at 37 °C in the presence of angiotensin, I, II or III (100 ng/ml) to determine the existence of a direct stimulating effect on prostaglandin (PG) production. PGE₂, PGF_2α, 6-keto PGF_1α and Thromboxane B₂ (TXB₂)_were determined by radioimmunoassay.For analysis of data variance, the results were separated according to whether the net output of PGE₂ was above or below 1.5 ng PGE₂ equivalent/mg tissue/30 min. Under low-output conditions, angiotensin I, II or III stimulated PGE₂ production significantly (p<0.02) and tended to augment PGF_2α production, while under high-output conditions no effect on PGE₂ or PGF_2α production was observed.Under either output condition, angiotensin I, II or III had no effect on 6-keto PGF_1α and TXB₂.