dinoprost and aglepristone

The aim of this in vitro study was to compare the uterokinetic activity of oxytocin and dinoprost, the natural PGF2α, with or without aglepristone, in canine myometrial fibers. Thirty-three bitches were allocated into one of four groups, depending on their estrous stage and whether or not they had received a treatment with aglepristone (metestrus aglepristone, n = 5; metestrus without treatment, n = 9; anestrus aglepristone, n = 9; anestrus without treatment, n = 10). After hysterectomy, longitudinal and circular uterine strips were mounted in organ baths. Oxytocin or PGF2α (10 nmol/l to 10 micromol/l) were applied non-cumulatively. A linear mixed effects models theory was used to compare the fiber effect, the aglepristone effect, and the treatment effect, from the area under the curves calculated from the contractile effect/concentration curves for each drug. Oxytocin and PGF2α induced concentration-dependent myometrial contractions in longitudinal (LF) and circular myometrial fibers (CF), indicating the presence of functional contractile oxytocin- and PGF2α-receptors in metestrus and anestrus. The contractile response to oxytocin was greater in LF than in CF in all of the groups; the response to PGF2α was greater in LF than in CF in non-treated bitches in anestrus and in treated bitches in metestrus. These results suggest that there is a difference in sensitivity or a heterogeneous distribution of oxytocin and PGF2α-receptors in the myometrial layers, which is independent of hormonal impregnation. The contractile response to oxytocin and PGF2α was significantly increased after aglepristone treatment in LF during metestrus, suggesting that the progesterone withdrawal induced by aglepristone has a role to play. The longitudinal myometrial layer also appeared to be the target for the two drugs at this stage. This study provides new information about canine uterine contractile activity, notably the differing behavior of myometrial CF and LF; in vivo studies are required to test the use of a combination of aglepristone and oxytocin in the treatment of canine pyometra.

Topics: Animals; Dinoprost; Dogs; Estrenes; Estrus; Female; In Vitro Techniques; Myometrium; Oxytocics; Oxytocin; Progesterone; Uterine Contraction

Oxytocin (OT) plays an important role as an inducer of uterine contractility, acting together with its receptor (OTR) to increase synthesis of prostaglandins. Although OT is commonly used in the treatment for dystocia and uterine inertia in the bitch, little attention has been paid to the role of OT in mechanisms regulating parturition in the dog, so that knowledge about the expression of OTR in the canine uterus and placenta is sparse. Consequently, the expression and cellular localization of OTR were investigated in canine utero/placental compartments and interplacental sites throughout pregnancy and at normal and antigestagen-induced parturition, by real-time PCR, immunohistochemistry, western blot and in situ hybridization. The utero/placental and interplacental expression of OTR was constant from pre-implantation until mid-gestation, with a significant increase observed at prepartum luteolysis. In antigestagen-treated mid-pregnant dogs, OTR was upregulated in both interplacental and utero/placental samples. Besides clear myometrial signals, cellular localization of OTR was evident in the endometrial surface epithelial, stromal and vascular endothelial cells. Weaker signals were observed in superficial and deep uterine glandular epithelial cells. Placental OTR was localized in maternal decidual cells and capillary pericytes. Finally, OTR was colocalized with the progesterone receptor (PGR) in maternal decidual cells, coinciding with previously reported increased availability of prostaglandins in the foetal part of the placenta during normal and induced parturition. These findings suggest involvement of OTR in the signalling cascade leading to the prepartum release of prostaglandins from the pregnant canine uterus.

Topics: Animals; Dinoprost; Dogs; Estrenes; Female; Gene Expression Regulation; Molecular Sequence Data; Parturition; Placenta; Pregnancy; Pregnancy, Animal; Receptors, Oxytocin; RNA, Messenger; Uterus

The study was designed to examine the aglepristone (RU534) mechanisms affecting the corpora lutea (CL) lifespan in pseudopregnant rabbits. Aglepristone (10 mg/kg b.w.) was injected subcutaneously twice at either early- or mid-luteal phase (Days 3 and 4, or Days 8 and 9, respectively) after induction of ovulation with GnRH (Day 0). Corpora lutea and uteri, explanted at days 6 and 11, were evaluated for immunohistochemistry and Western blotting of progesterone (PR) and estrogen (ER) receptors, cyclooxygenase 1 (COX1), COX2, and PGE2-9-ketoreductase (PGE2-9-K) enzymatic activities, and progesterone, PGF2α, and PGE2 in vitro synthesis. Independent of luteal stage, aglepristone prolonged the functional luteal phase by 3 Days over that of controls as assessed by blood progesterone profiles. Aglepristone decreased protein for ER during both luteal-stages in CL and uteri. Progesterone receptor protein was decreased by RU354 at Days 6 in the uterus and at Days 11 in CL, whereas RU534 increased PR at Days 11 in uteri. In the CL, RU534 enhanced progesterone production at Days 6 and 11, whereas it decreased PGF2α and increased PGE2 at Day 11. In the uteri, RU534 decreased PGF2α and increased PGE2 synthesis at both days. COX2 and PGE2-9K activities were decreased by RU534 in the CL at Day 11, whereas in the uteri COX2 increased and PGE2-9-K decreased at Days 6 and 11. In conclusion, these data on aglepristone effects suggest that progesterone has a regulatory role on luteal function through direct and uterine-mediated mechanisms in pseudopregnant rabbits.

Topics: Animals; Blotting, Western; Corpus Luteum; Cyclooxygenase 1; Cyclooxygenase 2; Dinoprost; Dinoprostone; Estrenes; Female; Hydroxyprostaglandin Dehydrogenases; Immunohistochemistry; Luteal Phase; Progesterone; Pseudopregnancy; Rabbits; Receptors, Estrogen; Receptors, Progesterone; Statistics, Nonparametric; Uterus

Expression of cyclooxygenase 2 (COX2, now known as PTGS2), prostaglandin E2 synthase (PTGES, PGES), and prostaglandin F2alpha synthase (PGFS), of the respective receptors PTGFR (FP), PTGER2 (EP2), and PTGER4 (EP4) and of the progesterone receptor (PGR, PR) was assessed by real-time PCR, immunohistochemistry (IHC), or in situ hybridization (ISH) in utero/placental tissue samples collected from three to five bitches on days 8-12 (pre-implantation), 18-25 (post-implantation), and 35-40 (mid-gestation) of pregnancy and during the prepartal luteolysis. Additionally, ten mid-pregnant bitches were treated with the antiprogestin aglepristone (10 mg/kg bw (2x/24 h)); ovariohysterectomy was 24 and 72 h after the second treatment. Plasma progesterone and 15-ketodihydro-PGF2alpha (PGFM) concentrations were determined by RIA. Expression of the PGR was highest before implantation and primarily located to the endometrium; expression in the placenta was restricted to the decidual cells. PTGS2 was constantly low expressed until mid-gestation; a strong upregulation occurred at prepartal luteolysis concomitant with an increase in PGFM. PGFS was upregulated after implantation and significantly elevated through early and mid-gestation. PTGES showed a gradual increase and a strong prepartal upregulation. PTGFR, PTGER2, and PTGER4 were downregulated after implantation; a gradual upregulation of PTGFR and PTGER2 occurred towards parturition. ISH and IHC co-localized PGFS, PTGFR, PTGES, and PTGS2 in the trophoblast and endometrium. The changes following application of aglepristone were in the same direction as those observed from mid-gestation to prepartal luteolysis. These data suggest that the prepartal increase of PGF2alpha results from a strong upregulation of PTGS2 in the fetal trophoblast with the withdrawal of progesterone having a signalling function and the decidual cells playing a key role in the underlying cell-to-cell crosstalk.

Topics: Animals; Dinoprost; Dogs; Estrenes; Female; Gestational Age; Hormone Antagonists; Labor, Induced; Oxytocics; Parturition; Placenta; Pregnancy; Pregnancy, Animal; Progesterone; Progesterone Congeners; Prostaglandin-Endoperoxide Synthases; Prostaglandins; Receptors, Prostaglandin

To increase our understanding of the endocrine changes associated with parturition in dogs, plasma concentrations of progesterone (P4), 15-ketodihydroprostaglandin F(2alpha) (PGFM), estradiol-17-beta (E2beta), cortisol, ACTH, prolactin (PRL), LH, and FSH were measured in six spontaneously whelping bitches and in six bitches in which parturition was induced with the progesterone-receptor blocker aglépristone on day 58 of pregnancy. Expulsion of pups in the induced group took place in the presence of P4 concentrations that were still elevated. PGFM concentrations increased before parturition in both groups, but levels were lower in the induced bitches. PGFM levels reached a maximum in both groups during parturition and quickly decreased in the spontaneously whelping group after parturition, but remained elevated in the induced group. In both groups, cortisol concentrations reached similar maximum levels during the last 30 h before the onset of expulsion. During the 3 days postpartum, cortisol concentrations were higher in the induced group. The highly variable ACTH concentrations did not differ significantly throughout the study within or between groups. In both groups, E2beta concentrations decreased and PRL concentrations increased between the late gestational period and the 30-h period before parturition. Concentrations of both LH (spontaneously whelping group) and FSH (both groups) decreased between late gestation and the postpartum period. The results of this study illustrate the hormonal changes around parturition in the bitch, and reveal that aglépristone-induced parturition is associated with still incomplete luteolysis, an altered PGFM profile, and elevated postpartum cortisol concentrations as compared with spontaneously whelping dogs.

Topics: Adrenocorticotropic Hormone; Animals; Dinoprost; Dogs; Estradiol; Estrenes; Female; Follicle Stimulating Hormone; Hormones; Hydrocortisone; Labor, Induced; Luteinizing Hormone; Parturition; Pregnancy; Progesterone; Prolactin

In order to evaluate the efficacy, the safety and the variation in plasma concentrations of estrogens, progesterone, PGFM, oxytocin, cortisol and prolactin after mid-pregnancy termination induced by aglepristone, 61 pregnant queens (33.3 + 4.2 days), were injected subcutaneously with 15 [corrected] mg/kg aglepristone, (Alizine) [corrected] repeated once 24 h later. Five queens served as control and received a placebo. The efficacy of aglepristone was 88.5% and termination of pregnancy was achieved in 50% of the queens within 3 days. Brief periods of depression and anorexia were noted in 9.3% of the queens before fetal expulsion (these symptoms were attributed to the phenomenon of fetal expulsions). Not one of the queens that aborted developed uterine disease. There were no changes in plasma concentrations of estrogen, prostaglandin, prolactin or oxytocin following aglepristone administration. However, there were significant increases in plasma concentrations of progesterone and cortisol 60 and 30 h, respectively, after aglepristone administration. Termination of pregnancy occurred with high plasma progesterone concentrations. Fetal expulsion was characterised by an increase in estrogen, PGFM and oxytocin concentrations, whereas prolactin and cortisol levels remained at a basal level.

Topics: Abortifacient Agents, Steroidal; Abortion, Induced; Abortion, Veterinary; Animals; Cats; Dinoprost; Estrenes; Estrogens; Female; Male; Oxytocin; Pregnancy; Progesterone

A higher incidence of fetal losses, especially after the use of artificial reproduction techniques, asks for more intensive monitoring of bovine pregnancies. In this study, a model for fetal death (FD) was created by administering the antiprogesterone aglepristone twice, at Day 47 and 48 of gestation (n=5). Control heifers received the solvent (n=5). The temporal relationships between changes in ultrasonographic appearance of fetal fluids and membranes, fetal heart rate (FHR) and peripheral plasma levels of pregnancy-associated glycoprotein (PAG) and PGF2alpha-metabolite as determined by radioimmunoassay associated with FD were monitored at eight hour intervals around treatment. For the analysis of plasma levels the period under study was divided into five epochs (T1: before injection of aglepristone/solvent; T2: from first to second injection; T3: from second injection to FD; T4: from diagnosis of FD to 56 h later; T5: from 56 h to 104 h after diagnosis of FD). Control heifers produced healthy calves at term, but in treated heifers, FD occurred on average at 58 (range 48-80) h after first injection of aglepristone. Fetal death was always preceded by a visible reduction of the amount of allantoic fluid and by segregation of the allantochorionic membrane from the endometrium. FHR remained rather constant in both groups, but a (non-significant) drop in FHR around 8h before FD was diagnosed in four of five treated animals. All fetuses were expulsed after FD. Levels of PAG remained constant or even slightly increased in controls, but decreased in treated animals from T2 onward: levels during T4 and T5 significantly differed from those during T1 and from values in controls during T4 and T5 (P<0.01). PGF2alpha-metabolite levels did not change in the controls, but in the treated group they were significantly higher during T3 when compared to T1 (P<0.05). After this increase, a sharp decrease in PGF2alpha-metabolite level occurred, reaching a significantly lower level at T5 when compared to control animals (P=0.01). It is concluded, that FD induced by aglepristone is preceded by ultrasonographic visible changes in fetal membranes and fluids and a rise in PGF2alpha-metabolite and is followed by a drop in PAG and PGF2alpha-metabolite.

Topics: Animals; Cattle; Cattle Diseases; Dinoprost; Disease Models, Animal; Estrenes; Female; Fetal Death; Gestational Age; Glycoproteins; Heart Rate, Fetal; Pregnancy; Pregnancy Proteins; Ultrasonography, Prenatal

Parturition was induced in ten Beagle bitches by injecting them subcutaneously with 15 mg aglepristone kg-1 (Alizine) at day 58 of gestation and 24 h later and subsequently at 2 h intervals with either 0.08 mg alfaprostol kg-1 (Alfabedyl) (group 1; five bitches) or 0.15 iu oxytocin kg-1 (Ocytocine S) (group 2; five bitches). Blood samples were collected every 4 h until the end of parturition to assay plasma concentrations of progesterone, dihydro-keto prostaglandin F2 alpha (PGFM), oxytocin, prolactin and cortisol. Parturition occurred in all bitches. The mean time of onset of parturition for both groups was not significantly different (32.6 +/- 3.7 h for group 1 versus 31.6 +/- 3.6 h for group 2), although the mean expulsion time for bitches from group 2 (4.5 +/- 1.8 h) was significantly shorter than that of bitches in group 1 (9.1 +/- 2.0 h). At birth, 93% of the pups were alive in group 2 compared with 86% in group 1. Peripheral plasma concentrations of progesterone increased significantly after the administration of aglepristone, but direct or indirect luteolysis was not induced, and plasma concentrations of oxytocin or cortisol did not change during the first 24 h after administration of aglepristone. PGFM concentrations increased significantly after 4 h of aglepristone administration. During the first 20 h after aglepristone administration, prolactin concentrations increased significantly. At parturition, bitches in group 2, which had the shorter expulsion time of pups, were characterized by significantly higher concentrations of oxytocin and PGFM than bitches in group 1.

Topics: Animals; Dinoprost; Dogs; Drug Administration Schedule; Estrenes; Female; Hormone Antagonists; Hydrocortisone; Labor, Induced; Oxytocin; Pregnancy; Progesterone; Prolactin; Prostaglandins F; Random Allocation

Seven bitches in early pregnancy (12.8 +/- 3.8 days after ovulation; group 1) and seven bitches in mid-pregnancy (32.0 +/- 1.53 days after ovulation; group 2) were used in this study. For each group, five bitches were treated with 0.10 mg aglepristone (Alizine) kg-1 and this dose was repeated 24 h later. Two control bitches received a placebo. Blood samples were collected at 6 h intervals to determine plasma concentrations of progesterone, dihydro-keto prostaglandin F2 alpha (PGFM), oxytocin, prolactin and cortisol. Parturition occurred in the four control bitches. All bitches treated with aglepristone aborted. In group 1, embryonic death occurred; in group 2, fetal expulsion occurred 60-132 h after administration of aglepristone. After pregnancy termination, the interoestrous interval of aglepristone-treated bitches was significantly shorter than that before treatment. Treatment with aglepristone did not modify plasma concentrations of progesterone, prostaglandin, oxytocin or cortisol within 24 h after its administration, but it induced, in mid-pregnancy (group 2) a discharge of prolactin within 12 h after its administration. As an abortifacient, aglepristone acted on the uterus and, therefore, did not have direct or immediate luteolytic properties. Termination of pregnancy occurred with high plasma progesterone concentrations. Fetal expulsion was characterized by an increase in the concentration of PGFM, but oxytocin and cortisol remained at basal concentrations.

Topics: Abortifacient Agents; Abortion, Induced; Abortion, Veterinary; Animals; Dinoprost; Dogs; Estrenes; Female; Gestational Age; Hormones; Hydrocortisone; Oxytocin; Pregnancy; Progesterone; Prolactin; Random Allocation