Prostaglandins are lipid compounds derived from fatty acids that are present in various tissues of horses. They are involved in a wide range of physiological processes, including the regulation of inflammation, blood flow, and reproductive functions. In equine medicine, prostaglandins are often studied for their role in modulating inflammatory responses and their potential therapeutic applications. These compounds can influence pain perception and are involved in processes such as parturition and the estrous cycle in mares. This page collects peer-reviewed research studies and scholarly articles that explore the synthesis, function, and clinical applications of prostaglandins in equine health.
Moses VS, Hardy J, Bertone AL, Weisbrode SE.To evaluate the effects of anti-inflammatory drugs on lipopolysaccharide (LPS)-challenged and -unchallenged equine synovial membrane in terms of production of prostaglandin E2 (PGE2) and hyaluronan, viability, and histomorphologic characteristics. Methods: Synovial membranes were collected from the carpal, tarsocrural, and femoropatellar joints of 6 adult horses. Methods: Synovial membranes from each horse were minced and pooled and explants were treated with one of the following: no drug (control), drug, LPS alone, or LPS and drug. Treatment drugs were phenylbutazone (PBZ), flunixin meglumine...
Campbell NB, Blikslager AT.Cyclooxygenase inhibitors are administered to horses to prevent endotoxin-induced elaboration of prostaglandins. However, PGE2 and PGI2 stimulate repair of injured intestine. There are 2 isoforms of cyclooxygenase: COX-1, which constitutively produces prostaglandins and COX-2, which is induced by inflammation. We hypothesised that the nonspecific cyclooxygenase inhibitor flunixin meglumine would retard repair of ischaemic intestinal injury by preventing production of reparative prostaglandins, whereas the selective COX-2 inhibitor, etodolac, would permit repair as a result of continued COX-1 p...
Van Hoogmoed LM, Snyder JR, Harmon F.To determine the in vitro effect of prostaglandin E2 (PGE2), PGF2alpha, PGI2; and nonsteroidal anti-inflammatory drugs (NSAID; ie, flunixin meglumine, ketoprofen, carprofen, and phenylbutazone) on contractile activity of the equine dorsal colon, ventral colon, and pelvic flexure circular and longitudinal smooth muscle. Methods: 26 healthy horses. Methods: Tissue collected from the ventral colon, dorsal colon, and pelvic flexure was cut into strips and mounted in a tissue bath system where contractile strength was determined. Incremental doses of PGE2, PGF2alpha,, PGI2, flunixin meglumine, carp...
von Rechenberg B, Guenther H, McIlwraith CW, Leutenegger C, Frisbie DD, Akens MK, Auer JA.To define the release of nitric oxide (NO), prostaglandin E2 (PGE2), and the neutral metalloproteinases (NMPs) in horses with subchondral cystic lesions (SCL) and to study bone resorption triggered by conditioned media of fibrous tissue of SCL in vitro. Methods: Equine explant cultures of fibrous tissue of SCL, and synovial membrane and articular cartilage of normal horses and horses affected with moderate and severe osteoarthritis were performed. NO, PGE2, and NMP concentrations of media samples were measured, and osteoclast formation and activation was studied in vitro. Methods: Experiment 1...
Woods J, Rigby S, Brinsko S, Stephens R, Varner D, Blanchard T.Two trials were conducted to investigate the effects of intrauterine infusion of PGE2 and uterine horn insemination on pregnancy rates in mares achieved by breeding with a suboptimal number of normal spermatozoa. Estrus was synchronized and mares were teased daily with a stallion to detect estrus. Mares in estrus were examined by transrectal palpation and ultrasonography to monitor follicular status. On the first day a 35-mm diameter follicle was present, hCG (1500 IU, iv) was administered and the mares were bred the next day. Mares (Trial 1, n = 34; Trial 2, n = 28) were inseminated with 25 m...
Nikolakopoulos E, Kindahl H, Gilbert CL, Goode J, Watson ED.Mating has been shown in many species to provoke the release of oxytocin (OT). In our study, various stimuli were applied to mares to study release of OT and prostaglandin F(2alpha) (PGF(2alpha)) associated with mating. Blood samples were collected from mares around the time of teasing both in oestrus and dioestrus and at mating. For comparison, blood samples were also collected at the time of manual manipulation of the genital tract and after intrauterine infusion of 500 ml phosphate buffered saline (PBS). Additional samples were collected 16 to 18 h after mating. Mating caused a significant ...
Vivrette SL, Kindahl H, Munro CJ, Roser JF, Stabenfeldt GH.Pituitary blood was collected from the intercavernal sinus in five mares before and during parturition, and in nine mares immediately after parturition to investigate oxytocin patterns during parturition and early lactation, and to determine the relationship between oxytocin, prostaglandin and arginine vasopressin during parturition. In four mares in which sample collection began at least 6 h before rupture of the chorioallantois, a significant increase (P < 0.05) in PGF(2alpha) concentration was detected before a significant increase in oxytocin concentration. Cross-correlation analysis of...
Kirker-Head CA, Chandna VK, Agarwal RK, Morris EA, Tidwell A, O'Callaghan MW, Rand W, Kumar MS.To correlate substance P content of synovial fluid with prostaglandin E2 content, radiographic evidence of joint abnormality, and anatomic location of the joint for normal and osteoarthritic joints of horses. Methods: Synovial fluid from 46 normal joints in 21 horses and 16 osteoarthritic joints in 10 horses. Methods: Normal and osteoarthritic joints were identified by clinical and radiographic examination, by response to nerve blocks, during scintigraphy or surgery, or by clinicopathologic evaluation. Substance P and prostaglandin E2 contents of synovial fluid were determined by radioimmunoas...
Vanderwall DK, Betschart RW, Squires EL.The objective of this study was to determine if the primary circulating metabolite of PGF2alpha, 13,14-dihydro-15-keto-PGF2alpha (PGFM), is biologically active and would induce luteolysis in nonpregnant mares. On Day 9 after ovulation, mares (n = 7/group) were randomly assigned to receive: 1) saline control, 2) 10 mg PGF2alpha or 3) 10 mg PGFM in 5 mL 0.9% sterile saline i.m. On Days 0 through 16, blood was collected for progesterone analysis. In addition, blood was collected immediately prior to treatment, hourly for 6 h, and then at 12 and 24 h after treatment for progesterone and PGFM analy...
Frean SP, Lees P.To investigate effects of the anti-arthritic agents hyaluronan and polysulfated glycosaminoglycan (PSGAG) on inflammatory metabolism in cultured equine synoviocytes. Methods: Synoviocytes cultured from samples obtained from the metacarpophalangeal joints of 4 horses. Methods: Equine synoviocytes were grown in monolayer culture. Synoviocytes were stimulated with lipopolysaccharide (LPS) and simultaneously treated with various concentrations of hyaluronan or PSGAG for 48 hours. Three hyaluronan preparations were compared. Prostaglandin E2 (PGE2) concentrations in culture medium were measured, us...
von Rechenberg B, McIlwraith CW, Akens MK, Frisbie DD, Leutenegger C, Auer JA.Nitric oxide (NO), prostaglandin E2 (PGE2), and the activity of neutral metalloproteinases (NMPs) were measured in conditioned media of equine synovial membrane and articular cartilage explant cultures from horses with normal joints (n = 7) and from horses affected with moderate (n = 7) or severe osteoarthritis (n = 14) as judged by macroscopic appearance. Normal articular cartilage appeared glossy and bluish-white, was of normal thickness and showed no evidence of discolouration, fibrillation or other cartilage discontinuity. Slight discolouration and fibrillation or minor clefts of the carti...
Cadario ME, Thatcher WW, Klapstein E, Merrit AM, Archbald LF, Thatcher MJ, LeBlanc MM.Two experiments were performed to investigate relationships between oxytocin, prostaglandin release, uterine emptying and fluid accumulation in the uterus. In Experiment 1, the effect of oxytocin on the pattern of prostaglandin release during uterine clearance of radiocolloid was measured in 5 normal mares and 5 mares with delayed uterine clearance. Uterine clearance was measured during estrus by scintigraphy at 0, 60 and 120 min after colloid infusion. After the 120-min reading, 20 IU, i.v., oxytocin were given, and the amount of colloid cleared was measured at 135, 150 and 180 min. Plasma wa...
Rigby S, Love C, Carpenter K, Varner D, Blanchard T.Eleven light-breed pregnant mares (335 to 347 d gestaton) were used to evaluate the use of prostaglandin E2 as a cervical ripening agent prior to induction of parturition during the months of April and May. Six hours prior to induction, each mare's cervix was examined per vagina for softness and dilation. Each mare was then assigned to 1 of 2 treatment groups: Group PGE mares (n = 7) received 2.0 to 2.5 mg prostaglandin E2 deposited intracervically; Group SAL mares (n = 4) received 0.5 mL of sterile NaCl deposited intracervically. Six hours later, the mares were readied for parturition by wrap...
Gastal MO, Gastal EL, Torres CA, Ginther OJ.The effects of oxytocin, prostaglandin F2 alpha (PGF2 alpha), and clenbuterol on uterine contractility and tone during anestrus and diestrus, and during mobility and postfixation of the embryonic vesicle were studied in 51 pony mares. Contractility was assessed by scoring real-time ultrasound images, and tone was assessed by transrectal digital compression. Scoring was done by an operator who had no knowledge of treatment assignments. In anovulatory mares primed with progesterone for 16 d, oxytocin did not significantly alter contractility but did stimulate an increase in tone, whereas clenbut...
Gastal EL, Gastal MO, Nogueira GP, Bergfelt DR, Ginther OJ.The effect of altered LH concentrations on the deviation in growth rates between the 2 largest follicles was studied in pony mares. The progestational phase was shortened by administration of PGF2alpha on Day 10 (Day 0=ovulation; n=9) or lengthened by daily administration of 100 mg of progesterone on Days 10 to 30 (n=11; controls, n=10). All follicles > or = 5 mm were ablated on Day 10 in all groups to initiate a new follicular wave. The interovulatory interval was not altered by the PGF2alpha treatment despite a 4-day earlier decrease in progesterone concentrations. Time required for growt...
Robinson SJ, Neal H, Allen WR.Equine embryos enter the uterus 144-156 h after ovulation, before which time the passage of embryos through the oviduct is halted in the region of the ampullary-isthmic junction. It is thought that further onward movement of embryos to the uterus is facilitated by secretion of prostaglandin E2 (PGE2) by the embryos, which relaxes the smooth muscle of the isthmus. In the present study, the effect of a single local application of PGE2 on oviductal transport was examined in 22 Thoroughbred and Pony mares that were inseminated on alternate days during oestrus. On day 4 after ovulation, the ipsilat...
Kindahl H, Odensvik K, Hansen B, Daels PF.The aim of this study was to characterize changes in PGF2alpha secretion in mares with persistent corpora lutea that were induced by administering altrenogest during oestrus. In Expt 1, PGF2alpha secretion was compared among mares undergoing normal oestrous cycles (n=7) and mares undergoing prolonged luteal phases (n=6), using the mean 15-ketodihydro-PGF2alpha (PGFM) plasma concentrations, peak PGFM concentrations and number of PGFM surges each day, from day 12 to day 16 of the luteal phase. In Expt 2, oxytocin-induced PGF2alpha secretion was characterized on days 13 and 16 of the luteal phase...
Stout TA, Lamming GE, Allen WR.Recent evidence indicates that, in mares, as in the domestic ruminants, oxytocin and its endometrial receptor play important roles in stimulating the pulsatile releases of prostaglandin F2 alpha from the endometrium that effect luteolysis. In the present experiment, continuous administration of oxytocin by subcutaneous minipump to five mares during days 8-20 after ovulation abolished luteolysis in four of them, while all four of the control mares infused similarly with saline underwent luteolysis at the expected time. When oxytocin administration began on day 10, instead of on day 8, after ovu...
Ababneh MM, Troedsson MH, Michelson JR, Seguin BE.Equine conceptuses are thought to produce antiluteolytic factors that inhibit endometrial PGF2alpha and, thus, prevent luteolysis in pregnant mares. The aim of the present study was to characterize partially the chemical nature of the prostaglandin inhibitory factor (PIF) produced by equine conceptuses in vitro. Embryos were collected from pregnant mares 13 +/- 0.5 days after ovulation and were cultured for 24 h. Harvested equine conceptus conditioned media (CCM) were assayed for antiluteolytic activity by determining the inhibition of endometrial PGF2alpha synthesis in vitro. Significant anti...
Bergfelt DR, Adams GP.Two experiments were performed to determine the efficacy of ultrasound-guided transvaginal follicle ablation for synchronizing ovarian function in mares. The experiments were initiated at random stages of the oestrous cycle in control (nonablated) and follicle-ablated mares. On day 0, all follicles > or =10 mm in diameter were punctured, aspirated and curettaged in ablated mares, and, on day 4, two doses of PGF2alpha were administered with a 12 h interval between the doses to both ablated and nonablated (control) mares. In Expt 1, hCG was administered to the ablated mares on the first or se...
Nikolakopoulos E, Kindahl H, Watson ED.Mares resistant (n=7) and susceptible (n=9) to persistent mating-induced endometritis were artificially inseminated (AI) during oestrus with chilled extended semen. Blood samples were collected from 30 min before AI, for 2 h after AI and again between 16 and 18 h after AI. Samples were assayed for oxytocin and the PGF2alpha metabolite 13,14-dihydro-15-keto PGF2alpha (PGFM). AI caused a significant increase in oxytocin concentrations in both the resistant and susceptible mares and there was no significant difference in oxytocin release between the two groups of mares. Mean PGFM concentrations w...
Shand N, Irvine CH, Turner JE, Alexander SL.Jugular blood samples were collected at 4 h intervals from six mares during an oestrous cycle to study the hormonal events that occur around the time of luteolysis. Blood samples from day 10 (day 0 = ovulation) until day 3 of oestrus were assayed for prostaglandin metabolite 13,14-dihydro-15-keto PGF2alpha (PGFM), oxytocin, prolactin, progesterone and oestrogen conjugates. PGF2alpha (0.5 or 1.5 mg) was administered to six mid-dioestrous mares and the oxytocin and prolactin responses were measured. One to five large (peak > or =2 x nadir) pulses of PGFM, oxytocin and prolactin were detected ...
Paccamonti DL, Pycock JF, Taverne MA, Bevers M, Van Der Weijden GC, Gutjahr S, Schams D, Blouin D.We investigated the half-life of oxytocin in reproductively normal mares and the prostaglandin response after oxytocin administrations. Mares were given oxytocin, 10 or 25 iu, i.v., on the day of, or 2 days after, ovulation, and frequent jugular blood samples were collected for analysis of oxytocin and Prostaglandin F metabolite (PGFM) by RIA. Neither dose of oxytocin nor day of treatment affected the half-life of the exogenous oxytocin, which was determined to be 6.8 min. A significant increase in PGFM was observed within 6 min of oxytocin administration and peak values were observed within 1...
Van Hoogmoed L, Rakestraw PC, Snyder JR, Harmon FA.To determine the in vitro effect of various prostaglandins (PG) and nonsteroidal anti-inflammatory drugs (NSAID) on contractile activity of the large-colon taenia of horses. Methods: 14 healthy horses. Methods: The taenia was collected from the ventral colon, cut into strips (2 X 10 mm), and mounted in a tissue bath system (20-ml capacity) that contained oxygenated Krebs buffer solution warmed to 37.5+/-0.5 C. After equilibration, incremental doses of PGE2, PGF2alpha, PGl2, flunixin meglumine, carprofen, ketoprofen, and phenylbutazone were added to the baths, and contractile activity was recor...
Bailey SR, Elliott J.Endotoxin has been implicated in the pathophysiology of acute laminitis. The aim of this study was to examine the direct effects of endotoxin on isolated equine digital blood vessels. Equine digital veins (EDV), incubated in Krebs-Henseleit solution containing lipopolysaccharide (LPS) (1 microg/ml) became hyporesponsive to 5-HT after 16 h. Cycloheximide and ibuprofen blocked this effect of LPS and increased the maximum response obtained to 5-HT when compared to control vessels. L-nitroarginine methyl ester (L-NAME) reversed the hyporesponsiveness caused by LPS. Vessels maintained in culture me...
Lees P, May SA, Hoeijmakers M, Coert A, Rens PV.The pharmacodynamics and enantioselective pharmacokinetics of vedaprofen were studied in six ponies in a two period cross-over study, in which a mild acute inflammatory reaction was induced by carrageenan soaked sponges implanted subcutaneously in the neck. Vedaprofen, administered intravenously at a dosage of 1 mg/kg, produced significant and prolonged inhibition of ex vivo serum thromboxane B2 (TXB2) synthesis and short-lived inhibition of exudate prostaglandin E2 (PGE2) and TXB2 synthesis. Vedaprofen also partially inhibited oedematous swelling and leucocyte infiltration into exudate. Vedap...
Behrendt-Adam CY, Adams MH, Simpson KS, McDowell KJ.A positive-feedback loop between luteal oxytocin and uterine prostaglandin F2 alpha (PGF) is a major signal for luteolysis in ruminants. Likewise, uterine PGF causes luteolysis in mares, but the involvement of oxytocin in this process is unclear. We wanted: 1) to determine if the oxytocin-neurophysin I (OT-NP I) gene is transcribed into mRNA in the endometrium of mares; and, if so, 2) to analyze relative changes in abundance of endometrial OT-NP I mRNA throughout the estrous cycle and during early stages of pregnancy. Endometrial biopsies were obtained from nonbred mares during estrus, and 5, ...
Kästner SB, Haines DM, Archer J, Townsend HG.Twenty-four Quarter Horse and Quarter Horse-cross yearlings were experimentally infected with influenza A virus (Influenza A/equine/Saskatoon/90 [H3N8]) by nebulisation. In a double blind controlled trial the horses were randomly assigned to 3 groups of 8 animals. Group 1 received a placebo, (carrier syrup), Group 2 the labelled dose and Group 3 twice the labelled dose of clenbuterol hydrochloride. All treatments were given per os b.i.d. for 10 days and started on the day of infection. The horses were monitored for clinical signs of influenza infection for 14 days. Bronchoalveolar lavages were...
Hammond RA, Hannon R, Frean SP, Armstrong SJ, Flower RJ, Bryant CE.To determine the amount of cyclooxygenase-2 (COX-2) and inducible nitric oxide synthase (iNOS) enzymes induced in vitro in equine alveolar macrophages in response to lipopolysaccharide (LPS). Sample Population-Alveolar macrophages obtained from 12 horses. Methods: Alveolar macrophages were collected by bronchoalveolar lavage from 12 horses and incubated for 6 hours with LPS (0.001 to 10 microg/ml) or vehicle. Total RNA was extracted and purified. After first-strand cDNA synthesis, mRNA induction was measured, using a polymerase chain reaction (PCR) technique for COX-2, iNOS, and glyceraldehyde...
Bader H, Röhrsheim C, Koene M, Meinecke B.Investigations in different species including the horse have demonstrated that prostaglandin F2 alpha (PGF2 alpha) is involved in initiating uterine contractions occurring during mating and artificial insemination (A.I.). Uterine contractions play an important role with respect to the sperm transport within the female genital tract. The objective of the present investigation was to evaluate whether the administration of PGF2 alpha (Dinoprost) synchronously to A.I. could have a positive effect on the pregnancy rate in mares. A field study including 346 warmblood-mares (age two to 20 years) belo...
MacKay RJ, Daniels CA, Bleyaert HF, Bailey JE, Gillis KD, Merritt AM, Katz TL, Johnson JC, Thompson KC.Ten horses were used in a crossover study to evaluate the effectiveness of eltenac against endotoxaemia. Eltenac (0.5 mg/kg bwt) or saline control was given i.v. then 15 min later, intravenous infusion of endotoxin was begun and continued for 120 min (total dose 100 ng/kg bwt). Horses were monitored for heart and respiratory rates, pulmonary and carotid arterial pressure and core body temperature. Blood was sampled at intervals for measurement of haematological variables and plasma concentrations of lactate, prostanoid metabolites, tumour necrosis factor (TNF) and stress hormones. In compariso...
Panzani S, Carluccio A, Probo M, Faustini M, Kindahl H, Veronesi MC.The aim of this study was to compare the plasma profiles of 15-ketodihydro-PGF(2α) (PGM) in healthy neonates of three different species from birth until the third week of life. Twenty-four horse foals, 12 donkey foals, and 9 calves were studied. Blood samples were collected at 10, 20 and 30 min after birth, at 3, 24 and 72 h after birth, and at 7, 10, 17 and 21 days of life. All mothers experienced normal gestation lengths and normal, spontaneous deliveries. All newborns were judged mature and viable. Hormone concentrations were higher (p < 0.05) in horse foals 20 and 30 min after birth compa...
Witkowski M, Witkowski M, Pawłowski K.The objective of this study was to compare the course of parturitions induced with sole oxytocin with those induced with the combination of intracervical prostaglandin E2 jelly and oxytocin. For this purpose 13 mares in advanced pregnancy were allocated to the groups pretreated with either intracervical PGE2 (experimental group) or saline (control group) two hours before intravenous oxytocin (5 IU) administration. The mares were compared with respect to cervical dilation diameter (CDD) 20 min. after oxytocin injection. Time intervals from the first oxytocin dose to: the first external signs of...
Podico G, Canisso IF, Ellerbrock RE, Dias NW, Mercadante VRG, Lima FS.The present study aimed to compare two methods of prostaglandin-induced abortion in mares by determining blood markers (progesterone, estradiol-17β, alpha-fetoprotein, 13,14-dihydro-15-keto-prostaglandin-F2α (PGFM)), B-mode ultrasonographic parameters, and time until loss of fetal heartbeat. It was hypothesized that intrauterine infusion of cloprostenol results in earlier fetal compromise than intramuscular administration. Ovarian structures (number and sizes of follicles and corpora lutea area), fetal heartbeat, and fetal mobility of thirteen singleton pregnancies were assessed daily by tra...
McCue PM, LeBlanc MM, Squires EL.Equine follicle stimulating hormone (eFSH) has been used to induce follicular development in transitional mares and problem acyclic mares, as well as superovulate cycling mares. The most efficacious protocol is to administer 12.5 mg eFSH, intramuscularly, twice daily beginning 5 to 7 days after ovulation when the diameter of the largest follicle is 20 to 25 mm. Prostaglandins are to be administered on the second day of eFSH therapy. Treatment with eFSH is continued for 3 to 5 days until follicle(s) are >or=35 mm in diameter. The mare is subsequently allowed to 'coast' for 36 h, after which hum...
Ginther OJ, Castro T, Baldrighi JM, Wolf CA, Santos VG.Five mares that developed idiopathic persistent corpus luteum (PCL) were compared with 5 mares with apparently normal interovulatory intervals (IOIs). Progesterone (P4) and a metabolite of prostaglandin F2α (PGFM) were assayed daily beginning on the day of ovulation (Day 0). Transition between the end of an initial progressive P4 increase and the beginning of a gradual decrease in P4 occurred on mean Day 6. The gradual decrease in P4 between Days 6 and 12 was less (approached significance, P < 0.06) in the PCL group than in the IOI group. The P4 concentration on Day 12 (before luteolysis i...
Templeton CB, Bottoms GD, Fessler JF, Ewert KM, Roesel OF, Johnson MA, Latshaw HS.Shock was induced in four groups of anesthetized ponies with an intravenous injection of Escherichia coli endotoxin [125 micrograms/kg]. Five minutes after endotoxin injection, the ponies were given no treatment (group A), flunixin meglumine (FM:1.1 mg/kg) (group B), dexamethasone (2 mg/kg) (group C), or prednisolone (10 mg/kg) (group D). Additionally, FM was given every 3 hours, and the steroids were given at 3, 9, and 24 hours following endotoxin. Hemodynamic measurements were made during the 4-hour anesthetic period. Blood samples were collected for the analysis of prostaglandins, blood che...
Olszewski MA, Robinson NE, Derksen FJ.In vitro responses of equine small peripheral airways (SA) and lung parenchyma (LP) were studied. We examined their contractile and relaxant responses and investigated effects of histamine, and endogenous prostanoids as these mediators may play a role in development or recurrent airway obstruction in horses (heaves). SA and LP electrical field stimulation (EFS) induced nearly maximal and partial frequency-dependent contractions, respectively. These contractions were virtually abolished in SA but only partially inhibited in LP by atropine (ATR) and tetrodotoxin (TTX). Methacholine (MCh) contrac...
Menzies-Gow NJ, Bailey SR, Berhane Y, Brooks AC, Elliott J.To determine the effect of endotoxin (lipopolysaccharide [LPS]) on vasoactive mediator production by cultured equine digital vein endothelial cells (EDVECs). Methods: EDVECs obtained from forelimb digital veins of 7 healthy adult horses. Methods: EDVECs were incubated with or without LPS (1 microg/mL) for 0, 2, 4, 6, 22, and 24 hours. The EDVECs were incubated for 18 hours with LPS (10 pg/mL to 1 microg/mL) with or without ibuprofen, cycloheximide, or L-nitroarginine methyl ester. Medium concentrations of prostacyclin, cyclic guanosine monophosphate, endothelin-1, and thromboxane A(2) were det...
Sissener TR, Squires EL, Clay CM.Prostaglandin F2alpha secretion by the uterine endometrium between Days 13 and 14 postovulation causes luteal regression in mares. A mechanism involving interruption or suppression of this secretion causes pregnancy to be maintained. The present study was designed to determine the age of the conceptus when maximal suppression of PGF2alpha secretion occurs. Mares were examined daily during estrus with ultrasonography (day 0 = day of ovulation). Conceptus tissues were recovered nonsurgically on Days 9 (n = 7), 12 (n = 5), 13 (n = 5), and 16 (n = 7) and uterine biopsies on Day 14. Both uterine an...
McNaughten J, Pozor M, Macpherson M, Kelleman A, Woodward E, Troedsson M.Mares who have not delivered a foal early in life may experience limitations in cervical relaxation, primarily during oestrus. A closed cervix prevents intrauterine deposition of semen during natural breeding, may delay uterine clearance after insemination leading to intrauterine fluid accumulation in, and subsequent infertility. Therefore, a reliable pharmacological method of dilating the equine cervix would have practical application in veterinary medicine. The goal of this study was to investigate the effectiveness of topically applied, synthetic prostaglandin E1 analogue (PGE1 ) for stimul...
Ousey JC, Fowden AL.Prostaglandins play an essential role during the perinatal period in the mare. Prostaglandin concentrations are low for the majority of pregnancy due to the regulatory action of progestagens on those enzymes responsible for metabolism of prostaglandins. Towards term, prostaglandin concentrations gradually increase, closely associated with upregulation of the fetal hypothalamo-pituitary-adrenal axis, stimulation of the prostaglandin synthesising enzyme PGHS-2 and changes in the ratio of progestagens and oestrogens. Recent evidence in the mare indicates that proinflammatory cytokines are key med...
Yamada ALM, do Prado Vendruscolo C, Marsiglia MF, Sotelo EDP, Agreste FR, Seidel SRT, Fülber J, Baccarin RYA, da Silva LCLC.Combined chondroitin sulfate (CS) and glucosamine (GlcN) has been widely used in oral formulations to prevent and treat osteoarthritis. CS is effective for controlling pain in osteoarthritic patients, whereas GlcN can stimulate glycosaminoglycan synthesis, thus reducing extracellular matrix degradation. Although several studies have been published on this topic, the effectiveness of treatment with oral CS and GlcN remains uncertain. The objective of this study was to analyze the progression of experimentally induced osteoarthritis in horses and verify the effectiveness of an oral compound base...
Yu MF, Wang ZW, Robinson NE, Derksen FJ.Four mechanisms that modulate airway smooth muscle function in normal horses were studied in the bronchi of horses affected by the airway obstructive disease heaves. Results were compared with data from historical controls studied by the same personnel in the same laboratory. Rings from the left cranial lobar bronchus (LB1) and small bronchi (5 mm OD) were suspended in muscle baths, and the isometric tension were measured. The inhibitory nonadrenergic noncholinergic (iNANC) function was studied in LB1. After the LB1 segments were pretreated with atropine and contracted with histamine, electric...
Pietrani M, Losinno L, Cuervo Arango J.In the present study, 2.228 cycles of 180 Polo Argentino donor mares from an embryo transfer program in Argentina were examined to evaluate the effects of: (1) Interval from Prostaglandin F2alpha analog treatment to ovulation (ITO) on embryo recovery rate (ERR); (2) ITO on number of embryos per flushing (EPF); (3) ITO on multiple ovulation (MO) rate; (4) ITO from donor mare on pregnancy rate (PR) in recipient mares. Mares were inseminated with fresh semen from 31 fertile stallions in the induced estrus. Embryo flushing was performed 7-8 days postovulation. Following embryo flushing, donor mar...
Vivrette SL, Kindahl H, Munro CJ, Roser JF, Stabenfeldt GH.Pituitary blood was collected from the intercavernal sinus in five mares before and during parturition, and in nine mares immediately after parturition to investigate oxytocin patterns during parturition and early lactation, and to determine the relationship between oxytocin, prostaglandin and arginine vasopressin during parturition. In four mares in which sample collection began at least 6 h before rupture of the chorioallantois, a significant increase (P < 0.05) in PGF(2alpha) concentration was detected before a significant increase in oxytocin concentration. Cross-correlation analysis of...
May SA, Hooke RE, Lees P.Prostaglandin E2 (PGE2) and stromelysin are produced by equine chondrocytes and synovial cells in vitro in response to recombinant human (rh) interleukin-1 (IL-1) alpha and beta, and equine mononuclear cell supernatants (MCS) containing IL-1. However, culture conditions are important. PGE2 concentrations increase in proportion to the concentration of fetal calf serum (FCS) in the culture medium, whereas stromelysin concentrations are inversely proportional to the concentration of FCS. Equine MCS, containing a lower concentration of IL-1 than the concentration of rhIL-1 used in these experiment...
Brunner TJ, Lescun TB, Moore GE, Grady SE, Davern AJ, Taylor SD.The mechanism by which nonsteroidal anti-inflammatory drugs mitigate pain caused by a heart bar shoe (HBS) model of lameness is unknown. The purpose of this study was to determine if this HBS model of lameness induces inflammation in horses. Five healthy adult horses from a university teaching herd were enrolled. A custom HBS was applied to the left front foot of each horse, followed by induction of the American Association of Equine Practitioners Lameness Score of 4. Inflammatory markers including serum amyloid A (SAA) concentration, local venous tumor necrosis factor alpha and prostaglandin ...
Hardee MM, Moore JN, Hardee GE.The efficacy of three agents which alter the metabolism of arachidonic acid was investigated in normal, conscious horses. A dose response evaluation was made of flunixin meglumine and phenylbutazone, two cyclo-oxygenase inhibitors, and of a selective thromboxane synthetase inhibitor, UK-38,485. Radioimmunoassay of thromboxane B2 (TxB2) and 6-keto prostaglandin F1 alpha (PGF1 alpha) was used to assess the concentrations of thromboxane A2 (TxA2) and prostacyclin (PGI2) respectively, in serum. Flunixin was the most potent inhibitor of serum TxB2 and 6-keto PGF1 alpha production. UK-38,485 also de...
Sayasith K, Bouchard N, Doré M, Sirois J.The objectives of the study were to clone the primary structure of the prostaglandin E2 receptor subtype 2 (PTGER2) cDNA and to characterize its regulation in equine follicles during gonadotropin-induced ovulation. Results from DNA isolation indicated that the equine PTGER2 cDNA encodes a predicted 353-amino acid protein, which is highly similar (76-85%) to known mammalian homologues. The regulation of PTGER2 was studied by semi-quantitative RT-PCR/Southern blot using preparations of theca interna and mural granulosa cells isolated from equine follicles 0-39 hr post-treatment with human chorio...
Ababneh MM, Troedsson MH.The aim of this study was to determine phospholipase A2 (PLA2) kinetics and activity in the mare's endometrium during the oestrous cycle and early pregnancy. Phospholipase A2 is responsible for the liberation of arachidonic acid from phospholipids, which is the first limiting step in prostaglandins synthesis. Phospholipase A2 activity was measured using an assay based on the liberation of oleic acid from 1-palmitoyl-2-[(14) C] oleoyl phosphatidylcholine. The enzyme was shown to be calcium dependent, to have an optimum pH of 8 and an apparent Michaelis constant of 127 μM. Enzyme activity was l...
Han X, Rossdale PD, Ousey J, Holdstock N, Allen WR, Silver M, Fowden AL, McGladdery AJ, Labrie F, Belanger A.15-hydroxy prostaglandin dehydrogenase (PGDH) is the critical enzyme that determines metabolism of primary prostaglandins. Its expression is determined in part by steroid hormones, particularly progesterone, formed from delta(5) steroids through 3beta-hydroxysteroid dehydrogenase (3beta-HSD) activity. To assess whether the regulation of PGDH might occur in a paracrine, autocrine or intracrine fashion, we used immunohistochemistry (IHC) to determine the localisation of key steroidogenic enzymes in the equine placenta and compared these patterns to the distribution of immunoreactive (IR-) PGDH. ...
Strzemienski PJ, Dyer RM, Sertich PL, Garcia MC, Kenney RM.The oestrous cycles of 20 mixed-breed mares were synchronized with daily injections of 10 mg oestradiol-17 beta and 150 mg progesterone given i.m. for 10 days. On the 10th day, 10-15 mg prostaglandin F-2 alpha was administered i.m. to induce oestrus. Neutrophils were isolated from jugular blood on the 2nd or 3rd day of oestrus, Days 5 and 7 after ovulation or during early pregnancy (Days 18-34 of pregnancy). Neutrophils were challenged with Staphylococcus aureus and their bactericidal activity examined after 30 and 120 min of incubation for a reduction of colony forming units. Bactericidal act...
Moore BR, Krakowka S, Mcvey DS, Cummins JM, Robertson JT.Protein and eicosanoid concentrations and procoagulant activity were determined in bronchoalveolar lavage fluid (BALF) from 32 Standardbred racehorses with inflammatory airway disease (IAD) and 6 control horses. Total protein, albumin and immunoglobulin G (IgG) concentrations were high (P < 0.05) in the BALF from horses with IAD, a finding consistent with exudation of plasma protein into the airway. Immunoglobulin A (IgA) concentrations also were increased (P < 0.05) which may signify local immunoglobulin production. Difference was not detected in prostaglandin E2 and 6-ketoprostaglandin...
Palmer E, Jousset B.Following an initial observation period of 13 days when plasma progesterone levels were determined, synchronization of oestrus and ovulation was investigated in thirty-three mares treated with a prostaglandin analogue ('Equimate') and HCG. Two courses of treatment were given 8 days apart and each consisted of a single intramuscular injection of Equimate (250 mug) followed 6 days later by an intramuscular injection of HCG (2500 i.u.). The first course was designed to remove all luteal tissue and to induce ovulation of any follicles that developed in response to the withdrawal of progesterone. T...
van Hoogmoed LM, Harmon FA, Stanley S, White J, Snyder J.The objective of this study was to determine if a correlation exists between the presence of nitric oxide and prostaglandin release in the equine ventral colon smooth muscle, since this relationship may accentuate the inflammatory process during intestinal injury. Tissue was collected from the ventral colon, cut into muscle strips oriented along the circular, longitudinal and taenial layers, and mounted in a tissue bath system. Samples of the bath fluid were collected before, following electrical field stimulation (EFS), and following EFS in the presence of L-NAME, a nitric oxide synthase inhi...
Alm CC, Sullivan JJ, First NL.Dexamethasone (100 mg/day) injected from Days 318 to 324 of pregnancy induced parturition. Progesterone (500 mg/day) administered daily from Day 318 of pregnancy also shortened gestation while oestrogen (50 mg/day) administered on the same schedule as progesterone had no such effect. Dexamethasone treatment superimposed on the oestrogen or progesterone treatments shortened gestation. Prostaglandin F2alpha alone did not induce parturition, unlike PGF2alpha with dexamethasone, or PGF2alpha given to ovariectomized mares.
Lyle SK.Placentitis is reported to be the cause of 9.8-33.5% of abortions, stillbirths and perinatal losses in horses. Bacterial infections are responsible for 53% of placentitis cases with Streptococcus equi ssp. zooepidemicus being isolated in 28% of these cases. Clinically, mares may have a vaginal discharge, show udder development, lactate prenatally and deliver a premature or dead foal. Major aspects of the pathogenesis of infectious preterm delivery that may require more effective therapeutic targeting are myometrial contraction, immunological aspects of preterm delivery, and the effects of proi...
Higgins AJ, Lees P, Sedgwick AD, Buick AR, Churchus R.In a two-part cross-over experiment in six ponies, an acute inflammatory reaction was generated by injecting carrageenin solution into subcutaneously-implanted tissue-cages lined with fibrovascular granulation tissue. In each part of the cross-over, half of the ponies received a novel phenylpyrazoline anti-inflammatory agent (BW540C) orally and half received a placebo treatment. BW540C inhibited platelet cyclo-oxygenase for 24 h but the reductions in exudate eicosanoid concentrations were less pronounced. A significant suppression in the rise of surface skin temperature in BW540C-treated ponie...
Fabová Z, Tarko A, Harrath AH, Alwasel S, Kotwica J, Sirotkin AV.Influence of oil-related product toluene and herbal remedy puncturevine Tribulus terrestris L. (TT) on female reproduction is known. Yet, mechanisms of their action on ovaries in different species and potential protective effect of TT against adverse toluene action remain to be established. We studied the effect of toluene, TT, and their combination on ovarian granulosa cells from two mammalian species (cows and horses). Viability, markers of proliferation (PCNA) and apoptosis (bax), steroid hormones, IGF-I, oxytocin, and prostaglandin F (PGF) release were analyzed by trypan blue exclusion tes...
