Prostaglandin Endoperoxide Synthase 2 (PTGS2) and Prostaglandins F2α and E2 Synthases (PGFS and PGES) Expression and Prostaglandin F2α and E2 Secretion Following Oestrogen and/or Progesterone Stimulation of the Feline Endometrium

Sex steroids in synergy with prostaglandins (PG) are involved in the regulation of cyclic ovarian function. In this study, we investigated the mRNA expression of three genes involved in arachidonic acid (AA) metabolism and hence PG production in domestic cats: PG‐endoperoxide synthase (PTGS2), PGF_2α synthase (PGFS) and PGE₂ synthase (PGES). Feline endometria (n = 16) were collected at oestrus and mid and late phases of pseudopregnancy. In addition, the effects of E₂ and/or P₄ on PG secretion and gene expression on endometrial explants were studied in an in vitro culture system. Expression levels of all examined genes were up‐regulated at the mid phase of pseudopregnancy. The effects of E₂ and/or P₄ treatment on both PG secretion and expression of the genes were observed after 12 h of culture. Expression of PGES was significantly up‐regulated by E₂ plus P₄ at oestrus and the mid phase of pseudopregnancy and was also up‐regulated by a single treatment with P₄ at late pseudopregnancy (p < 0.05). Simultaneous incubation with E₂ and P₄ up‐regulated PTGS2 gene expression at oestrus and mid‐luteal phase (p < 0.05). Progesterone plus E₂ significantly increased PGE₂ secretion at oestrus and the mid phase of pseudopregnancy. However, treatment with E₂ and/or P₄ affected neither PGF_2α secretion nor PGFS expression at any phase after 12 h of culture. The overall findings indicate that genes involved in PG synthesis are up‐regulated at the mid phase of pseudopregnancy. An increase in PGE₂ secretion and up‐regulation of PGES and PTGS2 are the main responses of the endometrium to treatment with E₂ and P₄ at oestrus and the mid phase of pseudopregnancy in the cat. These data support the hypothesis that ovarian sex steroids via endometrial PGE₂ are involved in endocrine homoeostasis, especially at oestrus and the mid, but not the late, phase of pseudopregnancy in cats.     

Effects of Prostaglandin E2, Prostaglandin F2α and Endotoxin on Plasma Calcium Levels in The Goat

Intravenous administration of 2.6–3.3 µg/kg of an endotoxin from Salmonella typhimurium to goats caused a marked drop in plasma Ca levels associated with an increase of prostaglandin synthesis and release measured as peripheral plasma levels of 15-keto-13,14-dihydro-PGF_{2 α}. This is one of the main metabolites of PGF_{2 α}, but also PGE_{2 α} is partly metabolised to this compound. The infusion of 10 mg of PGF_{2 α} lowered plasma Ca levels. Ten mg of PGE₂ did not change Ca concentrations significantly.     

Effects of Ethanol on Synthesis of Prostaglandin F2α in Bovine Females

Ethanol stimulates the production of prostaglandins in many species. The purpose of this study was to verify the effect of ethanol on the production of prostaglandin F2α (PGF2α) and luteolysis in bovine females. In the first experiment, Holstein cows at day 17 of the oestrous cycle were treated with 100% ethanol (0.05 ml/kg of body weight, IV; n = 5), saline (0.05 ml/kg of body weight, IV; n = 4) or synthetic prostaglandin (150 μg of D‐cloprostenol/cow, IM; n = 4). The plasma concentrations of 13, 14‐dihydro‐15‐keto PGF2α (PGFM; the main metabolite of PGF2α measured in the peripheral blood) were assessed by radioimmunoassay (RIA). There was an acute release of PGFM in response to ethanol comparing to other treatments (p ≤ 0.05). However, only cows treated with PGF2α underwent luteolysis. In the second experiment, endometrial explants of cross‐bred beef cows (n = 4) slaughtered at day 17 of the oestrous cycle were cultured for 4 h. During the last 3 h, the explants were cultured with medium supplemented with 0, 0.1, 1, 10 or 100 μl of 100% ethanol/ml. Medium samples were collected at hours 1 and 4 and concentrations of PGF2α were measured by RIA. Ethanol did not induce PGF2α production by the endometrium. In conclusion, ethanol does not cause luteolysis in cows because it stimulates production of PGF2α in extra‐endometrial tissues.     

Estrus Synchronization in Sheep and Goats Using Combinations of GnRH,Progestagen and Prostaglandin F2α

The objective of this experiment was to evaluate the effect of GnRH, progestagen and prostaglandin F_2α on estrus synchronization in sheep and goats. Sixty Awassi ewes and 53 Damascus does were used in the study. The experiment started at the beginning of the breeding season (June/July). The same treatments were applied to sheep and goats as follows: no treatment (CON), 14‐day progestagen sponges and 600 IU equine chorionic gonadotropin (S), gonadotropin releasing hormone followed 5 days later by prostaglandin F_2α (GP) and gonadotropin releasing hormone, progestagen sponges for 5 days and prostaglandin F_2α on the day of sponge removal (GSP). None of the ewes in the S group lambed from mating during the induced cycle. A greater lambing rate (p < 0.05) was observed in the GSP group compared with the CON and S groups while the GP group was intermediate. The number of lambs born per lambed ewe was similar among the CON, GP and GSP groups. However, the number of lambs per exposed ewe was greater (p < 0.05) in the GSP than the remaining groups. The induced cycle kidding rate was 77% for all treatments combined. Similar kidding rate were observed among treatments. The numbers of kids born per kidded and exposed doe from mating during the induced estrus were also similar among treatments. Greater numbers of multiple births were observed in the GP and GSP than in the S group. In conclusion, a combination of GnRH, progestagen sponges and PGF_2α can be effective in synchronizing estrus and improving fecundity in sheep and goats. Although the use of GnRH–PGF_2α was effective, the addition of progestagen sponges at the time of GnRH administration appeared to improve reproductive parameters.     

Prostaglandin F2α Metabolite Levels Following an Embryo Transfer Procedure in the Mare

Hormonal, chemical, and mechanical stimuli can activate the arachidonic acid cascade and result in formation of prostaglandins and related substances. These compounds can have a profound role in the initiation of the inflammatory process (Higgins & Lees 1984). Prostaglandin (PG) F_2α is the key hormone in reproductive physiology with well-known effects on reproductive performance e.g. luteolysis and abortion. An activation of the arachidonic acid cascade, caused by mechanical manipulation during an embryo transfer procedure, might be one explanation for early embryonic loss.     

Temporal Relationships and Repeatability of Follicle Diameters and Hormone Concentrations within Individuals in Mares

Data were collected daily from 23 mares during two consecutive interovulatory intervals (IOIs). Several significant (p < 0.05) new observations on temporal relationships were made. The FSH increase that begins before ovulation temporarily plateaued on the day of discharge of follicular fluid into the peritoneal cavity in association with ovulation. During the declining portion of the pre-ovulatory oestradiol surge, an abrupt reduction in the rate of decrease occurred in synchrony with the peak of the LH surge and is consistent with a negative effect of LH on oestradiol. Repeatability within mares was based on the following positive and significant correlations between the two IOIs: (i) length of the interval between ovulations and between ovulation and the beginning of follicle deviation; (ii) diameter of the pre-ovulatory follicle on days -3 to -1; (iii) number of follicles in diameter classes of 2–5 mm (correlation for 22/23 days of the IOI), 5.1–10 mm (18/23 days), 10.1–15 mm (12/23 days) and 15.1–20 mm (12/23 days) and (iv) concentrations of FSH (18/23 days) and LH (22/23 days). The greatest repeatability for the follicle-diameter classes occurred in the 2–5 mm class, and thereafter the repeatability progressively decreased as the diameters for the classes increased. Results demonstrated measurable repeatability within mares for several end points between consecutive IOIs.     

Effects of Flunixin Meglumine and Prostaglandin F2α Treatments on the Development and Quality of Bovine Embryos In Vitro

Assisted reproduction procedures, such as embryo transfer (ET) and artificial insemination (AI), in cattle could induce the secretion of prostaglandin F₂‐alpha (PGF₂α) from uterine horns which may in turn interrupt embryo development and implantation. This study investigated the effect of flunixin meglumine (FM), prostaglandin F2 alpha (PGF2α) and FM combined with PGF2α supplementation in culture medium (IVC‐II) on the development and quality of in vitro produced bovine embryos. The development rate of embryos was significantly higher in the FM group (33.3%) than in control (24.3%), PGF₂α (23.9%) and FM + PGF₂α groups (24.5%). The percentage of hatched blastocysts was also higher (p < 0.05) in the FM group (41.2%) than in the control (27.8%) and PGF₂α groups (19.8%). While, there was no significant difference in total cell number in all experimental groups, the number of apoptotic cells was significantly higher in the PGF₂α group (8.2 ± 6.6) than in the control (4.7 ± 3.2), FM (4.7 ± 2.5) and FM + PGF₂α (4.9 ± 3.4) groups. Detected by real‐time PCR, secreted vesicle seminal protein 1 (SSLP1) and prostaglandin G/H synthase 2 (PTGS2) gene expression decreased (p < 0.05) in the PGF₂α group. However, SSLP1 and PTGS2 gene expression in the FM + PGF₂α group returned to their baseline levels, similar to the control and FM groups. Caspase 3 (CAPS3) gene expression increased in the PGF₂α group compared with other groups (p < 0.05). In conclusion, addition of FM in vitro culture significantly improved embryo development as well as alleviated the negative impact of PGF₂α.     

Intra‐ovarian dynamic blood flow in pseudopregnant rabbits during prostaglandin F2α‐induced luteolysis

In the present study, we evaluated the dynamic changes of intra‐ovarian blood flow, by real‐time colour‐coded and pulsed Doppler ultrasonography, as well as the immunopresence of prostaglandin F2α (PGF2α) receptor (FP) and peripheral plasma progesterone concentrations in pseudopregnant rabbit after PGF2α treatments at either early‐ (4 days) and mid‐luteal (9 days) stages. During the pre‐treatment observation interval of one hour, the ovarian blood flows showed a fluctuating pattern. Independently of luteal stage, PGF2α administration caused a fourfold decline in the blood flow within 40 min that was followed 50 min later by a reactive hyperaemia that lasted several hours, while the resistive index showed an opposite trend. Twenty‐four hour later, the blood flow was one half that measured before PGF2α injection. At day 4 of pseudopregnancy, PGF2α did not affect peripheral plasma progesterone concentrations, but at day 9, it caused functional luteolysis as progesterone levels declined 6 hr later to reach basal values after 24 hr. The changes in the ovarian blood flows of pseudopregnant rabbits receiving PGF2α were accompanied by simultaneous changes in the resistance index. This biphasic response in the blood flow and vascular resistances likely reflects reactive hyperaemia following vasoconstriction. By immunohistochemistry, strong positive immune reaction for FP was detected in the cytoplasm of endothelial cells of ovarian arteries, veins and capillaries. In conclusion, these results suggest that PGF2α could acutely regulate the ovarian blood flow of pseudopregnant rabbits, even if there is no evidence of a blood flow reduction anticipating luteolysis.     

前列腺素E2和F2α对LPS刺激后奶牛子宫内膜上皮细胞COX-1和COX-2表达的影响

试验旨在阐明前列腺素E₂（prostaglandin E₂,PGE₂）和F_2α（prostaglandin F_2α,PGF_2α）对体外培养的奶牛子宫内膜上皮细胞中环氧合酶-1（cyclooxygenase-1,COX-1））与环氧合酶-2（cyclooxygenase-2,COX-2）表达的影响。培养奶牛子宫内膜上皮原代细胞和传代细胞,第4代细胞以1×10⁶个/孔接种于6孔板,以10^-7mol/L PGE₂和PGF_2α分别预处理细胞24 h,以100 ng/mL细菌脂多糖（lipopolysaccharides,LPS）刺激细胞4、8和12 h后分别提取RNA和总蛋白质,采用实时荧光定量PCR与Western blotting等技术检测COX-1与COX-2 mRNA和蛋白质的表达量。结果表明,与对照组相比,COX-1 mRNA表达量在PGE₂单独作用4、8和12 h后显著上调（P<0.05）;COX-2 mRNA表达量在PGE₂单独作用4和12 h后显著上调（P<0.05）,PGE₂单独处理使COX-1、COX-2蛋白表达量均显著上调（P<0.05）。与对照组相比,LPS刺激8和12 h时COX-1 mRNA表达量显著下调（P<0.05）,LPS刺激后COX-1蛋白表达量无显著变化（P>0.05）;LPS刺激后4、8和12 h时COX-2 mRNA表达量显著上调（P<0.05）,LPS刺激后COX-2蛋白表达量显著上调（P<0.05）。与LPS单独处理组相比,LPS+PGE₂处理组在8和12 h时COX-1和COX-2 mRNA表达量均显著上调（P<0.05）,同时COX-1和COX-2蛋白表达量也显著上调（P<0.05）。PGF_2α在LPS未刺激和刺激后对COX-1和COX-2 mRNA的表达无显著影响（P>0.05）,仅在PGF_2α单独处理8和12 h后COX-1 mRNA表达量上调（P<0.05）。两种激素联合处理与各自单独处理及LPS单独刺激相比,对COX-1和COX-2 mRNA表达具有一定的协同诱导作用。     

α- and β-adrenoceptors in the sheep urinary bladder

A study was undertaken to determine the presence and distribution of alpha- and beta-adrenoceptors in the sheep bladder body and base. In the bladder body, noradrenaline and isoproterenol induced relaxation which was significantly inhibited by propranolol, pafenolol and butoxamine. In the presence of propranolol (10(-5) M), noradrenaline induced a small contraction, as well as phenylephrine, but B-HT 920 failed to cause any effect on the bladder body. In the bladder base, noradrenaline caused a contraction that was significantly inhibited by prazosin but not by yohimbine. Phenylephrine also induced a contractile response in this structure which was inhibited by prazosin. Isoproterenol caused a relaxation that was significantly inhibited by propranolol and pafenolol but not by butoxamine. Relaxation was mediated by both beta 1 and beta 2-adrenoceptors in the detrusor muscle and by beta 1-adrenoceptors in the bladder base. Alpha 1-adrenoceptors contributed to maintain the detrusor tone and contract the bladder base.     

Measurement of C‐reactive protein and Prostaglandin F2α Metabolite Concentrations in Differentiation of Canine Pyometra and Cystic Endometrial Hyperplasia/Mucometra

Canine pyometra is a dioestrus period disease in which systemic inflammatory response syndrome (SIRS) is a common outcome due to the response of the body to the bacterial infection. The purpose of this study was i) to differentiate canine pyometra and cystic endometrial hyperplasia (CEH)/mucometra by measuring serum C‐reactive protein (CRP) and prostaglandin F_2α metabolite (PGFM) concentrations in blood and ii) to compare serum concentrations of CRP and PGFM in bitches with a pathological uterus (pyometra or CEH/mucometra) to concentrations in bitches with a healthy uterus. Mean CRP concentrations were found significantly higher (p < 0.001) in dogs with pyometra compared to those with CEH/mucometra or healthy uterus. However, no statistical difference could be detected between the groups for mean PGFM concentrations. Mean white blood cell count (WBC), alkaline phosphatase (ALP) and total protein concentrations were found significantly higher (p < 0.001) in dogs with pyometra. Escherichia coli was the most frequently isolated microorganism from dogs with pyometra (64.3%). Edwardsiella spp. was detected in a single case of pyometra for the first time. In conclusion, our results demonstrate that serum CRP concentrations were increased in dogs with pyometra and thus we conclude that serum CRP concentration but not PGFM might be useful as a marker to differentiate a case of CEH/mucometra from pyometra in female dogs. To the authors' knowledge, this is the first report in which Edwardsiella spp. has been isolated in the canine uterus.     

Development of One vs Multiple Ovulatory Follicles and Associated Systemic Hormone Concentrations in Mares

Ablation of follicles ≥  6 mm in diameter and treatment with PGF2α 10 days after ovulation were used to induce the development of ovulatory waves. Comparisons were made between induced waves with one (33 waves, 72%) and multiple (13 waves, 28%) ovulatory follicles. Diameter deviation was defined as the separation of follicles into dominant and subordinate categories. Multiple ovulatory follicles were preceded by more (p < 0.001) follicles ≥ 20 mm at the beginning of deviation, higher LH preceding deviation (approached significance, p < 0.08), lower (p < 0.05) concentrations of FSH on the day of deviation and thereafter, and higher (p < 0.0003) oestradiol by 2 days after deviation. During the peri-ovulatory period, systemic hormone concentrations for waves with multiple ovulations involved higher oestradiol before ovulation (approached significance, p < 0.07), lower FSH (p < 0.04) before and after ovulation, and both higher progesterone (p < 0.05) and lower LH (p < 0.05) beginning the day after ovulation. Results indicated that by the beginning of deviation there were more follicles ≥  20 mm and subsequently greater oestradiol production in waves that led to the development of multiple ovulatory follicles, and during the peri-ovulatory period differences between one and multiple ovulations were consistent with the negative effects of the ovarian hormones on the gonadotropins.     

Expression of fibronectin and its integrin receptor α5β1 in canine mammary tumours

Fibronectin and its integrin receptor α5β1 were studied by immunohistochemical methods in five normal canine mammary glands, four dysplastic glands and 18 mammary tumours. The aim of the study was to evaluate the possible changes in the α5β1 integrin receptor and its ligand fibronectin in relation to the metastatic capacity of canine mammary neoplasms. The immunostaining of α5β1 was very uniform in the hyperplastic glands but uneven in the mammary tumours. The expression of α5 and β1 was diminished in metastatic tumours but there were some α5-positive cells with pronounced features of malignancy and immaturity. Stromal fibronectin was increased in most cases and cytoplasmic staining of fibronectin was observed in epithelial and myoepithelial cells in mammary neoplasms but not in normal or dysplastic mammary tissue. There was no relationship between the content of α5β1 and the expression of fibronectin in canine mammary tumours.     

Expression of VEGFR and PDGFR‐α/‐β in 187 canine nasal carcinomas

Radiotherapy represents the standard of care for intranasal carcinomas. Responses to tyrosine kinase inhibitors (TKIs) have been reported but data on expression of target receptor tyrosine kinases (rTKs) is limited. This study characterizes the expression of vascular endothelial growth factor receptor (VEGFR), platelet‐derived growth factor receptor (PDGFR)‐α and PDGFR‐β in canine intranasal carcinomas. Histological samples from 187 dogs were retrieved. Immunohistochemistry was performed using commercially available antibodies. Expression of rTKs was classified into weak, moderate or intense and additionally recorded as cytoplasmic, membranous, cytoplasmic‐membranous, nuclear or stromal. VEGFR was expressed in 158 dogs with predominantly moderate expression (36.9%) and a cytoplasmic‐membranous expression pattern (70.9%). PDGFR‐α was detected in 133 with predominantly weak expression (57.9%) and cytoplasmic pattern (87.9%). PDGFR‐β was identified in 74 patients with a predominantly moderate expression (17.6%) and cytoplasmic expression pattern (63.5%). Co‐expression of rTKs was common. These results confirm expression of VEGFR, PDGFR‐α and PDGFR‐β in canine intranasal carcinomas and support the utility of TKIs.     

Conversion of Cortisone to Cortisol and Prostaglandin F2α Production by the Reproductive Tract of Cows at the Late Luteal Stage In Vivo

Previous in vitro studies demonstrated that bovine endometrium has the capacity to convert inactive cortisone to biologically active cortisol (Cr) and that Cr inhibits cytokine‐stimulated prostaglandin F_2α (PGF) production. This study was carried out to test the hypothesis that bovine reproductive tract has the capacity to convert cortisone to Cr in vivo and to evaluate the effects of intravaginal application of exogenous cortisone on uterine PGF secretion during the late luteal stage. The temporal relationships between PGF and Cr levels in uterine plasma were also determined. Catheters were inserted into jugular vein (JV), uterine vein (UV), vena cava caudalis (VCC) and aorta abdominalis (AA) of six cows on Day 15 of the oestrous cycle (ovulation = Day 0) for frequent blood collection. On Day 16, the cows were divided randomly into two groups and infused intravaginally with vaseline gel (10 ml; control; n = 3) or cortisone dissolved in vaseline gel (100 mg; n = 3). Blood samples were collected at ?2, ?1, ?0.5, 0, 0.5, 1, 1.5, 2, 3, 4, 5 and 6 h after treatments (0 h). Intravaginal application of cortisone increased plasma concentrations of Cr between 0.5 and 1.5 h in UV, at 0.5 h in VCC, at 1 h in JV and at 1.5 h in AA. The plasma concentrations of PGF in UV and of PGF metabolite in JV were greater at 0.5 and 1 h in the cortisone‐treated animals than in control animals. The levels of PGF in UV blood plasma decreased after Cr reached its highest levels. The overall findings suggest that the female reproductive tract has the capacity to convert cortisone to Cr in vivo. Based on the temporal changes of PGF and Cr levels in the uterine plasma, a biphasic response in PGF secretion was found to be associated to the Cr increase induced by the cortisone treatment at the late luteal stage in non‐pregnant cows.     

Plasma Concentrations of 13, 14‐Dihydro‐15‐keto‐Prostaglandin F2α, Progesterone and Cortisol During Periparturient Period in Yaks (Poephagus grunniens L.)

An attempt was made to determine plasma concentrations of, 13, 14‐dihydro‐15‐keto‐prostaglandin F_2α (PGFM), cortisol and progesterone during periparturient period in yak. Plasma PGFM level showed an increasing trend beginning day 5 prior to parturition (0.48 ± 0.14 ng/ml) and increased steeply thereafter to reach a peak level (17.16 ± 1.31 ng/ml) on the day of parturition. The levels, then, declined sharply on day 1 postpartum to reach 1.20 ± 0.40 ng/ml and thereafter declined gradually over the days to reach 0.28 ± 0.09 ng/ml on day 20 postpartum and this level was maintained with fluctuation within narrow limits thereafter till conclusion of the blood sampling on day 90 post‐calving. The plasma progesterone concentration on days 7 and 6 before parturition was high (2.10 ± 0.10 and 2.12 ± 0.10 ng/ml, respectively). The level then decreased gradually and abrupt fall was observed 1–2 days before parturition and became basal on day of parturition (0.24 ± 0.04 ng/ml). This basal level was maintained till the end of the blood sampling on day 90 postpartum. Plasma cortisol level showed an increasing trend beginning day 2 prior to parturition (2.36 ± 0.65 ng/ml) and increased steeply thereafter to reach a peak level (26.65 ± 5.28 ng/ml) on the day of parturition. The levels, then, declined gradually over the days and touched 2.36 ± 0.25 ng/ml on day 3 postpartum and this level was maintained with fluctuation within narrow limits thereafter till day 7 post‐calving.     

Clinical and Luteolytic Effects of Fenprostalene (A Prostaglandin F(2)alpha Analogue) in Mares

A study was carried out to determine the luteolytic effect of fenprostalene, a prostaglandin F₂α analogue, in mares Ten mares, that included seven cyclic mares, lactating mares and a pregnant mare were used in two experiments. In the first experiment, seven mares were treated subcutaneously with 250 μg fenprostalene and in the second experiment ten mares, including the seven mares used in the first experiment, were treated with fenprostalene and artificially inseminated during the induced estrus. Fenprostalene caused luteolysis in the normal cycling mares and the pregnant mare. Mares showed estrus within one to five days after treatment. Six of the ten mares conceived during the induced estrus and a further two conceived during the next estrus. The compound produced a side effect consisting of a small, raised, sometimes painful skin swelling at the injection site, which lasted for one to two days.