Receptors in horses are specialized protein molecules located on the surface of or within cells. They are responsible for receiving and transmitting signals from various stimuli, such as hormones, neurotransmitters, and environmental changes. These receptors play a significant role in numerous physiological processes, including immune response, sensory perception, and cellular communication. Types of receptors found in horses include adrenergic receptors, which mediate responses to adrenaline and noradrenaline, and muscarinic receptors, involved in the parasympathetic nervous system. Variations in receptor function and expression can influence equine health and behavior. This page compiles peer-reviewed research studies and scholarly articles that explore the types, functions, and implications of receptors in equine biology and health management.
Bruschetta G, Zanghì G, Giunta RP, Ferlazzo AM, Satué K, D'Ascola A, Fazio E.Horse transport is considered a cause of stress in animals and is known to affect the 5-HT concentrations in both the brain and other tissues. The aim of this research was to investigate the effect of horse transportation and slaughter stress on plasma serotonin's concentration and the expression levels of the related 5-HT1B and 5-HT2A receptors in PBMCs. Furthermore, the IL-12 levels and a variety of blood parameters, including triglycerides, total cholesterol, glucose, aspartate aminotransferase, creatine phosphokinase, lactate dehydrogenase, were also considered. This research was carried o...
Galinelli NC, Bamford NJ, de Laat MA, Sillence MN, Harris PA, Bailey SR.Insulin dysregulation in horses is characterised by hyperinsulinaemia and/or tissue insulin resistance and is associated with increased risk of laminitis. There is growing evidence in other species that dopamine attenuates insulin release from the pancreas; however, this has yet to be examined in horses. The present study aimed to identify whether there are cells capable of producing or responding to dopamine within the equine gastrointestinal mucosa and pancreas. Tissue samples were collected from the stomach, small and large intestines, and pancreas of six mature horses following euthanasia....
Nissen SD, Saljic A, Carstensen H, Braunstein TH, Hesselkilde EM, Kjeldsen ST, Hopster-Iversen C, D'Souza A, Jespersen T, Buhl R.Second-degree atrioventricular (AV) block at rest is very common in horses. The underlying molecular mechanisms are unexplored, but commonly attributed to high vagal tone. Unassigned: To assess whether AV block in horses is due to altered expression of the effectors of vagal signalling in the AV node, with specific emphasis on the muscarinic acetylcholine receptor (M) and the G protein-gated inwardly rectifying K (GIRK4) channel that mediates the cardiac current. Unassigned: Eighteen horses with a low burden of second-degree AV block (median 8 block per 20 h, IQR: 32 per 20 h) were assign...
Zamith Cunha R, Semprini A, Salamanca G, Gobbo F, Morini M, Pickles KJ, Roberts V, Chiocchetti R.Cannabinoid receptors are expressed in human and animal trigeminal sensory neurons; however, the expression in the equine trigeminal ganglion is unknown. Ten trigeminal ganglia from five horses were collected post-mortem from an abattoir. The expression of cannabinoid receptors type 1 (CB1R) and type 2 (CB2R), and the cannabinoid-related receptors like transient receptor potential vanilloid type 1 (TRPV1), peroxisome proliferator-activated receptor gamma (PPARɣ), and G protein-related receptor 55 (GPR55) in the trigeminal ganglia (TG) of the horse were studied, using immunofluorescence on cry...
Stejskalova K, Janova E, Splichalova P, Futas J, Oppelt J, Vodicka R, Horin P.Toll-like receptors (TLRs) represent an important part of the innate immune system. While human and murine TLRs have been intensively studied, little is known about TLRs in non-model species. The order Perissodactyla comprises a variety of free-living and domesticated species exposed to different pathogens in different habitats and is therefore suitable for analyzing the diversity and evolution of immunity-related genes. We analyzed TLR genes in the order Perissodactyla with a focus on the family Equidae. Twelve TLRs were identified by bioinformatic analyses of online genomic resources; their ...
Barnabé MA, Elliott J, Harris PA, Menzies-Gow NJ.Hypoadiponectinaemia is a risk factor for endocrinopathic laminitis, but the directionality and nature of its association with insulin dysregulation is unclear. Objective: To investigate the effects of short-term induced hyperinsulinaemia and dexamethasone challenge on circulating [total adiponectin] and whole blood expression of adiponectin (AdipoR1 and AdipoR2), insulin, and insulin-like growth factor 1 (IGF-1) receptors in insulin-sensitive ponies. Methods: In vivo experiment. Methods: Six never-laminitic, insulin-sensitive, native-breed UK ponies first underwent a dexamethasone challenge (...
Spruit CM, Zhu X, Tomris I, Ríos-Carrasco M, Han AX, Broszeit F, van der Woude R, Bouwman KM, Luu MMT, Matsuno K, Sakoda Y, Russell CA, Wilson IA....Influenza A viruses (IAV) initiate infection by binding to glycans with terminal sialic acids on the cell surface. Hosts of IAV variably express two major forms of sialic acid, -acetylneuraminic acid (NeuAc) and -glycolylneuraminic acid (NeuGc). NeuGc is produced in most mammals, including horses and pigs, but is absent in humans, ferrets, and birds. The only known naturally occurring IAV that exclusively bind NeuGc are extinct highly pathogenic equine H7N7 viruses. We determined the crystal structure of a representative equine H7 hemagglutinin (HA) in complex with NeuGc and observed high simi...
Galiazzo G, De Silva M, Giancola F, Rinnovati R, Peli A, Chiocchetti R.The activation of cannabinoid and cannabinoid-related receptors by endogenous, plant-derived or synthetic cannabinoids may exert beneficial effects on pain perception. Of the cannabinoids contained in Cannabis sativa, cannabidiol (CBD) does not produce psychotropic effects and seems to represent a molecule having great therapeutic potential. Cannabidiol acts on a great number of cannabinoid and cannabinoid-related G-protein-coupled receptors and ionotropic receptors which have, to date, been understudied in veterinary medicine particularly in equine medicine. Objective: To localise the cellula...
Chiocchetti R, Rinnovati R, Tagliavia C, Stanzani A, Galiazzo G, Giancola F, Silva M, Capodanno Y, Spadari A.Growing evidence recognises cannabinoid receptors as potential therapeutic targets for pain. Consequently, there is increasing interest in developing cannabinoid receptor agonists for treating pain. As a general rule, to better understand the actions of a drug, it would be of extreme importance to know the cellular distribution of its specific receptors. The localisation of cannabinoid receptors in the dorsal root ganglia of the horse has not yet been investigated. Objective: To localise the cellular distribution of canonical and putative cannabinoid receptors in the equine cervical dorsal roo...
Mißbach S, Aleksic D, Blaschke L, Hassemer T, Lee KJ, Mansfeld M, Hänske J, Handler J, Kammerer R.The CEA gene family is one of the most rapidly evolving gene families in the human genome. The founder gene of the family is thought to be an ancestor of the inhibitory immune checkpoint molecule CEACAM1. Comprehensive analyses of mammalian genomes showed that the CEA gene family is subject to tremendous gene family expansion and contraction events in different mammalian species. While in some species (e.g. rabbits) less than three CEACAM1 related genes exist, were in others (certain microbat species) up to 100 CEACAM1 paralogs identified. We have recently reported that the horse has also an e...
Zizzadoro C, Caruso M, Punzi S, Crescenzo G, Zongoli F, Belloli C.Hemodynamic perturbations, partly resulting from abnormal vasoconstriction of digital vessels, have been implicated in the pathogenesis of bovine and equine laminitis. This study compared the responsiveness of isolated bovine (BDA) and equine (EDA) digital arteries to pharmacological agents that stimulate receptor systems involved in the regulation of normal vessel tone. The role of the endothelium and the short- and longer-term effects of an experimentally induced endothelial damage were also evaluated. Species-related differences were found in the vessel reactivity to all of the receptor ago...
Feng KH, Gonzalez G, Deng L, Yu H, Tse VL, Huang L, Huang K, Wasik BR, Zhou B, Wentworth DE, Holmes EC, Chen X, Varki A, Murcia PR, Parrish CR.The A/H3N8 canine influenza virus (CIV) emerged from A/H3N8 equine influenza virus (EIV) around the year 2000 through the transfer of a single virus from horses to dogs. We defined and compared the biological properties of EIV and CIV by examining their genetic variation, infection, and growth in different cell cultures, receptor specificity, hemagglutinin (HA) cleavage, and infection and growth in horse and dog tracheal explant cultures. Comparison of sequences of viruses from horses and dogs revealed mutations that may be linked to host adaptation and tropism. We prepared infectious clones o...
Retamal CA, Dias AJ, Brasil FC, Lanzana FR, López ML.The expression of α-D-mannosidase activity was fluorometrically and electrophoretically assessed in spermatozoa, epididymal fluid and homogenates of stallion epididymal tissue. Enzyme activity had regional differences; it was higher (P<0.05) in samples from the cauda epididymal region than in samples from the proximal caput region (largely composed of efferent ducts). Based on enzyme activity, as a function of pH of the assay substrate, electrophoretic analysis in native and native/SDS-PAGE conditions, and the effect of inhibitors or activators, we inferred the presence of at least two cat...
Prause AS, Guionaud CT, Stoffel MH, Portier CJ, Mevissen M.To evaluate the expression of the 5-hydroxytryptamine 4 (5-HT4) receptor subtype and investigate the modulating function of those receptors on contractility in intestinal tissues obtained from horses without gastrointestinal tract disease. Methods: Smooth muscle preparations from the duodenum, ileum, and pelvic flexure collected immediately after slaughter of 24 horses with no history or signs of gastrointestinal tract disease. Methods: In isometric organ baths, the contractile activities of smooth muscle preparations in response to 5-hydroxytryptamine and electric field stimulation were asses...
Talboom JS, Engler-Chiurazzi EB, Whiteaker P, Simard AR, Lukas R, Acosta JI, Prokai L, Bimonte-Nelson HA.In women, ovarian hormone loss at menopause has been related to cognitive decline, and some studies suggest that estrogen-containing hormone therapy (HT) can mitigate these effects. Recently, the Women's Health Initiative study found that conjugated equine estrogens, the most commonly prescribed HT, do not benefit cognition. Isolated components of conjugated equine estrogens (tradename Premarin(®)) have been evaluated in vitro, with delta(8,9)-dehydroestrone (∆(8)E1) and equilin showing the strongest neuroprotective profiles. It has not been evaluated whether ∆(8)E1 or equilin impact cogn...
Hajek P, Ungemach FR, Abraham G.Muscarinic acetylcholine receptor (mAChR)-mediated guanine nucleotide-binding regulatory protein (G protein) activation and the functional interaction between receptors and the respective G proteins were investigated using an agonist-induced [(35)S]guanosine-5'-O-(gamma-thiotriphosphate) ([(35)S]GTPgammaS)-binding approach in membranes of 3 native equine airway segments (trachea, bronchus and lung), which differ tremendously in mAChR density and subtype distribution; especially subtypes that couple negatively to adenylyl cyclase through G(i/0) proteins, i.e. M(2) receptors. The assay was initi...
Treonze KM, Alves K, Fischer P, Hagmann WK, Hora D, Kulick A, Vakerich K, Smith ND, Lingham RB, Maniar S, Reger TS, Zunic J, Munoz B, Prasit P....The purpose of this study was to characterize the alpha(4)beta(1) receptor (CD49d/CD29, very late antigen-4, VLA-4) on circulating equine leukocytes and to evaluate the intrinsic potency of an alpha(4)beta(1) receptor antagonist (Compound B) in the horse. Ultimately, these studies would allow us to determine the suitability of treating recurrent airway obstruction (RAO; heaves) affected horses by blocking the cellular recruitment of lymphocytes and neutrophils into the lung. The data demonstrates the alpha(4)beta(1) integrin is present on horse lymphocytes and neutrophils (fluorescence-assiste...
Keen JA, Hillier C, McGorum BC, Nally JE.Endothelin-1 (ET-1) may be a key mediator in the pathogenesis of laminitis, but endothelin-mediated responses in the venous microcirculation of the equine foot have yet to be fully characterised. Objective: To characterise the response of equine laminar veins to ET-1 and evaluate the ET-1 receptor subtypes that mediate this response. Methods: Small veins (150-500 microns) draining the equine digital laminae from healthy horses and ponies subjected to euthanasia at an abattoir were investigated using wire myography. Concentration response curves were constructed for ET-1 in the presence of ETA ...
Thomasy SM, Moeller BC, Stanley SD.To compare the density and binding characteristics of opioid receptor subtypes in horse, rat, and guinea pig cerebral cortex and cerebellum. Methods: Prospective receptor binding study. Methods: Whole brains were obtained from four neurologically normal adult horses during necropsy. Rat and guinea pig brains were obtained commercially. Methods: The cerebellum and cerebral cortex were dissected from each brain, and tissue homogenates prepared. A radioligand binding technique with the highly selective ligands [(3)H]-DAMGO, [(3)H]-U69593, and [(3)H]-DPDPE was used to identify the mu- (mu), kappa-...
Marti M, Mevissen M, Althaus H, Steiner A.The goal of this study was to investigate the effect of bethanechol (BeCh) on contractility patterns of smooth muscle preparations of equine duodenum descendens, jejunum, caecum and pelvic flexure in vitro. Concentration-response relationships were developed for BeCh using in vitro assays with and without preincubation of muscarinic (M) receptor antagonists for M2 and M3 receptors. BeCh induced a significant, concentration-dependent increase in contractile response in equine intestine in specimens with circular orientation. The maximal effect was largest for jejunal specimens with no differenc...
Chidambaram RM, Eades SC, Moore RM, Hosgood G, Venugopal CS.To characterize the in vitro response of equine cecal longitudinal smooth muscle (CLSM) to endothelin (ET)-1 and assess the role of ETA and ETB receptors in those ET-1-induced responses. Methods: 36 horses without gastrointestinal tract disease. Methods: To determine cumulative concentration-response relationships, CLSM strips were suspended in tissue baths containing graded concentrations of ET-1 (10(-9) to 10(-6)M) with or without BQ-123 (ETA receptor antagonist); with or without IRL-1038 (ETB receptor antagonist); or with both antagonists at concentrations of 10(-9), 10(-7), and 10(-5)M. To...
Schneider DA, Sayegh AI.There exists individual enteroendocrine cells spread throughout the gastrointestinal mucosa that release specific peptide, as well as nonpeptide, hormones to have various endocrine action on target cells bearing cell surface receptors selectively sensitive to these regulatory substances. Following receptor activation, a series of events is set into motion that serves to transduce the information imparted to the target cell. Such transduction mechanisms are numerous, and may be excitatory or inhibitory to the cell depending upon which G-protein subunits the receptor is coupled.
Prieto D, Arcos LR, Martínez P, Benedito S, García-Sacristán A, Hernández M.The distribution of neuropeptide Y (NPY)-immunorective nerves and the receptors involved in the effects of NPY upon electrical field stimulation (EFS)- and noradrenaline (NA)-elicited contractions were investigated in horse penile small arteries. NPY-immunoreactive nerves were widely distributed in the erectile tissues with a particularly high density around penile intracavernous small arteries. In small arteries isolated from the proximal part of the corpora cavernosa, NPY (30 nM) produced a variable modest enhancement of the contractions elicited by both EFS and NA. At the same concentration...
Katz LM, Marr CM, Elliott J.To compare the responses of equine digital arteries (EDAs) and equine digital veins (EDVs) to endothelin-1 (ET-1) and determine the role of the endothelium and type of receptors involved in the modulation and mediation of those responses, respectively. Methods: 5 to 9 palmar digital vessels/experiment from 28 healthy horses. Methods: Rings of dissected vessels were mounted under tension between force transducer wires in organ baths containing Krebs-Henseleit solution at 30 degrees C. Responses of EDAs and EDVs (with intact [+e] or denuded [-e] endothelium) to cumulative concentrations of ET-1 ...
Hellyer PW, Bai L, Supon J, Quail C, Wagner AE, Mama KR, Magnusson KR.To test the hypothesis that the distribution, density, and subtype of opioid and alpha (alpha)-2 adrenergic receptors within the central nervous system (CNS) are significantly different between horse and dog. Methods: Prospective experimental study. Methods: Three dogs (3 years of age) and three horses (2-5 years of age). Animals were opioid- and alpha-2 agonist-free at the time of euthanasia. Methods: Brain tissue was obtained at 126 days post-surgery from dogs and 72 days post-surgery from horses. The brains were removed, sectioned coronally into 1-cm slabs, frozen in methylbutane, which was...
Benamou AE, Marlin DJ, Callingham BC, Hiley RC, Lekeux R.There is currently little published information about the effects of endothelin-1 (ET-1), a potent endogenous spasmogen of vascular and airway smooth muscle, on pulmonary vasculature and airways or which ET receptor subtypes mediate ET-1-induced vasoconstrictive and bronchoconstrictive action in the horse. Objective: To investigate the effect of endothelin-1 (ET-1) on smooth muscle from isolated equine pulmonary artery and bronchus. In addition, the roles of ETA and ETB receptors in ET-1 mediated contraction in these tissues were assessed. Methods: The force generation of ring segments from pu...
Koenig JB, Cote N, LaMarre J, Harris WH, Trout DR, Kenney DG, Monteith G.To identify and characterize motilin receptors in equine duodenum, jejunum, cecum, and large colon and to determine whether erythromycin lactobionate competes with porcine motilin for binding to these receptors. Methods: Specimens of various segments of the intestinal tracts of 4 adult horses euthanatized for reasons unrelated to gastrointestinal tract disease. Methods: Cellular membranes were prepared from smooth muscle tissues of the duodenum, jejunum, pelvic flexure, and cecum. Affinity and distribution of motilin binding on membrane preparations were determined by use of 125I-labeled synth...
Martínez AC, Prieto D, Hernández M, García-Sacristán A, Benedito S.The present investigation was designed to evaluate the effect of histamine on isolated rings of horse deep dorsal penile vein. Under precontracted or basal conditions, histamine evoked an endothelium-independent contraction. Preincubation of the vein rings with the selective H1 receptor antagonist, mepyramine, shifted the concentration-response curve for histamine and to the H1 receptor agonist 2-pyridylethylamine to the right in a competitive manner. Pretreatment with cimetidine, a specific H2 receptor antagonist, did not modify the pEC50 and maximal contraction of the histamine response. Cim...
Martínez AC, Rivera L, Raposo R, García-Sacristán A, Benedito S.The effect of histamine (10(-9)-10(-3) M) on horse penile dorsal artery was evaluated. Precontracted vessels showed a biphasic response (relaxation-contraction) to histamine, while at basal tone, histamine only induced a contractile effect. The H1 receptor agonist, 2-pyridylethylamine (PEA) (10(-9)-10(-3) M), induced concentration-dependent relaxation in precontracted rings and provoked vasoconstriction at basal tone. Mepyramine (10(-9)-10(8) M), an H1 receptor antagonist, competitively antagonized the relaxant response to histamine (pA2 = 9.7) and PEA (pA2 = 9.2). At basal tone, mepyramine (1...
The Journal of physiologyFebruary 16, 2000
Volume 523 Pt 1, Issue Pt 1 131-138 doi: 10.1111/j.1469-7793.2000.t01-3-00131.x
Wang YX, Kotlikoff MI.1. The signalling pathway underlying histamine activation of non-selective cation channels was investigated in single equine tracheal myocytes. Application of histamine (100 microM) activated the transient calcium-activated chloride current (ICl(Ca)) and sustained, low amplitude non-selective cation current (ICat). The H1 receptor antagonist pyrilamine (10 microM) blocked activation of ICl(Ca) and ICat. Simultaneous application of histamine (100 microM) and caffeine (8 mM) during H1 receptor blockade activated ICl(Ca), but not ICat. Neither the H2 receptor antagonist cimetidine (20 microM) nor...
Feng KH, Gonzalez G, Deng L, Yu H, Tse VL, Huang L, Huang K, Wasik BR, Zhou B, Wentworth DE, Holmes EC, Chen X, Varki A, Murcia PR, Parrish CR.The A/H3N8 canine influenza virus (CIV) emerged from A/H3N8 equine influenza virus (EIV) around the year 2000 through the transfer of a single virus from horses to dogs. We defined and compared the biological properties of EIV and CIV by examining their genetic variation, infection, and growth in different cell cultures, receptor specificity, hemagglutinin (HA) cleavage, and infection and growth in horse and dog tracheal explant cultures. Comparison of sequences of viruses from horses and dogs revealed mutations that may be linked to host adaptation and tropism. We prepared infectious clones o...
Bousfield GR, Butnev VY, Gotschall RR, Baker VL, Moore WT.There are two species for which both pituitary and placental gonadotropins are readily available, humans and horses. The human gonadotropins are better characterized than equine gonadotropins. Nevertheless, the latter are very interesting because they provide exceptions to some of the general structure-function principles derived from studies on human and other mammalian gonadotropins. For example, separate genes encode the hLH beta and hCG beta subunits while a single gene encodes eLH beta and eCG beta. Thus, eCG and eLH differ only in their oligosaccharide moieties and eLH is the only LH tha...
The Journal of physiologyFebruary 16, 2000
Volume 523 Pt 1, Issue Pt 1 131-138 doi: 10.1111/j.1469-7793.2000.t01-3-00131.x
Wang YX, Kotlikoff MI.1. The signalling pathway underlying histamine activation of non-selective cation channels was investigated in single equine tracheal myocytes. Application of histamine (100 microM) activated the transient calcium-activated chloride current (ICl(Ca)) and sustained, low amplitude non-selective cation current (ICat). The H1 receptor antagonist pyrilamine (10 microM) blocked activation of ICl(Ca) and ICat. Simultaneous application of histamine (100 microM) and caffeine (8 mM) during H1 receptor blockade activated ICl(Ca), but not ICat. Neither the H2 receptor antagonist cimetidine (20 microM) nor...
Stankov B, Cozzi B, Lucini V, Fumagalli P, Scaglione F, Fraschini F.Melatonin receptors were characterized in the brains of three mammals (rabbit, horse and sheep) by an in vitro binding technique, using 2-[125I]iodomelatonin as labelled ligand. Although binding sites for melatonin have been described recently in several vertebrate species (including the sheep), the rabbit and the horse have not been the subject of investigation so far. Apart from characterization, the present report describes receptor distribution in a number of brain regions, thus allowing for direct interspecies comparison under the same methodological conditions. 2-[125I]iodomelatonin labe...
Stewart F, Allen WR.The role of equine chorionic gonadotrophin (CG, formerly termed Pregnant Mare serum Gonadotrophin, PMSG) in maintaining equine pregnancy was investigated by examining the effects of this hormone on the maternal ovaries during early gestation and relating these findings to the receptor binding activities of CG in vitro. Measurement of plasma progestagen profiles in mares and donkeys carrying horse, donkey, mule ( female horse X male donkey) and hinny (female donkey X male horse) conceptuses confirmed that CG induced several secondary ovulations and thus maintained maternal progestagen concentra...
Prieto D, Hernández M, Rivera L, García-Sacristán A, Simonsen U.The distribution of neuropeptide Y (NPY)-immunoreactive (IR) nerves, as well as the functional effects of NPY and the Y1- and Y2-receptor agonists, [Leu31,Pro34]NPY and NPY(13-36), respectively, have been investigated in vitro in both visceral and arterial smooth muscle of the horse intravesical ureter. NPY-IR nerve fibres were widely distributed along the entire length of the ureter, although the intravesical part was the most richly innervated region, and the only one where NPY-IR ganglion cells were found. NPY (10(-7) M) did not affect either basal tone or spontaneous rhythmic contractions ...
Wilson SM, Rakhit S, Murdoch R, Pediani JD, Elder HY, Baines DL, Ko WH, Wong PY.Experiments were undertaken using cultured equine sweat gland epithelial cells that express purine receptors belonging to the P2U subclass which allow the selective agonist uridine triphosphate (UTP) to increase the concentration of intracellular free Ca2+ ([Ca2+]i). Experiments using pertussis toxin (Ptx), which inactivates certain guanine-nucleotide-binding proteins (G-proteins), showed that this response consisted of Ptx-sensitive and Ptx-resistant components, and immunochemical analyses of the G-protein alpha subunits present in the cells showed that both Ptx-sensitive (alpha i1-3) and Ptx...
Chiocchetti R, Rinnovati R, Tagliavia C, Stanzani A, Galiazzo G, Giancola F, Silva M, Capodanno Y, Spadari A.Growing evidence recognises cannabinoid receptors as potential therapeutic targets for pain. Consequently, there is increasing interest in developing cannabinoid receptor agonists for treating pain. As a general rule, to better understand the actions of a drug, it would be of extreme importance to know the cellular distribution of its specific receptors. The localisation of cannabinoid receptors in the dorsal root ganglia of the horse has not yet been investigated. Objective: To localise the cellular distribution of canonical and putative cannabinoid receptors in the equine cervical dorsal roo...
Cheng FP, Gadella BM, Voorhout WF, Fazeli A, Bevers MM, Colenbrander B.The aim of the present study was to investigate whether the induction of stallion sperm acrosome reaction (AR) by progesterone is mediated by binding of progesterone to a receptor on the sperm plasma membrane or to an intracellular progesterone receptor. Progesterone-BSA conjugate labeled with fluorescein isothiocyanate (P-BSA-FITC) in combination with a vital stain, ethidium homodimer, was applied to visualize the presence of the progesterone receptor on living spermatozoa. Alternatively, an indirect immunofluorescence technique employing a monoclonal antibody (C-262) against human intracellu...
Spruit CM, Zhu X, Tomris I, Ríos-Carrasco M, Han AX, Broszeit F, van der Woude R, Bouwman KM, Luu MMT, Matsuno K, Sakoda Y, Russell CA, Wilson IA....Influenza A viruses (IAV) initiate infection by binding to glycans with terminal sialic acids on the cell surface. Hosts of IAV variably express two major forms of sialic acid, -acetylneuraminic acid (NeuAc) and -glycolylneuraminic acid (NeuGc). NeuGc is produced in most mammals, including horses and pigs, but is absent in humans, ferrets, and birds. The only known naturally occurring IAV that exclusively bind NeuGc are extinct highly pathogenic equine H7N7 viruses. We determined the crystal structure of a representative equine H7 hemagglutinin (HA) in complex with NeuGc and observed high simi...
Koenig JB, Cote N, LaMarre J, Harris WH, Trout DR, Kenney DG, Monteith G.To identify and characterize motilin receptors in equine duodenum, jejunum, cecum, and large colon and to determine whether erythromycin lactobionate competes with porcine motilin for binding to these receptors. Methods: Specimens of various segments of the intestinal tracts of 4 adult horses euthanatized for reasons unrelated to gastrointestinal tract disease. Methods: Cellular membranes were prepared from smooth muscle tissues of the duodenum, jejunum, pelvic flexure, and cecum. Affinity and distribution of motilin binding on membrane preparations were determined by use of 125I-labeled synth...
Hellyer PW, Bai L, Supon J, Quail C, Wagner AE, Mama KR, Magnusson KR.To test the hypothesis that the distribution, density, and subtype of opioid and alpha (alpha)-2 adrenergic receptors within the central nervous system (CNS) are significantly different between horse and dog. Methods: Prospective experimental study. Methods: Three dogs (3 years of age) and three horses (2-5 years of age). Animals were opioid- and alpha-2 agonist-free at the time of euthanasia. Methods: Brain tissue was obtained at 126 days post-surgery from dogs and 72 days post-surgery from horses. The brains were removed, sectioned coronally into 1-cm slabs, frozen in methylbutane, which was...
Minelli A, Allegrucci C, Mezzasoma I, Ronquist G, Lluis C, Franco R.Membrane vesicles of horse seminal plasma present at their surface a highly specific serine-type protease, dipeptidyl peptidase IV/CD26, a surface antigen known to characterize human prostasomes. Horse sperm cells expressed at their surface A(1) adenosine receptors (A(1)AR) and ecto-adenosine deaminase (ecto-ADA), both detected by immunoblot analysis, whereas CD26 was visualized at the equatorial segment by immunofluorescence microscopy. In addition to CD26, horse membrane vesicles showed ecto-ADA. The fusion process between horse sperm cells and vesicles was evidenced by confocal microscopy, ...
Galiazzo G, De Silva M, Giancola F, Rinnovati R, Peli A, Chiocchetti R.The activation of cannabinoid and cannabinoid-related receptors by endogenous, plant-derived or synthetic cannabinoids may exert beneficial effects on pain perception. Of the cannabinoids contained in Cannabis sativa, cannabidiol (CBD) does not produce psychotropic effects and seems to represent a molecule having great therapeutic potential. Cannabidiol acts on a great number of cannabinoid and cannabinoid-related G-protein-coupled receptors and ionotropic receptors which have, to date, been understudied in veterinary medicine particularly in equine medicine. Objective: To localise the cellula...
Schneider DA, Sayegh AI.There exists individual enteroendocrine cells spread throughout the gastrointestinal mucosa that release specific peptide, as well as nonpeptide, hormones to have various endocrine action on target cells bearing cell surface receptors selectively sensitive to these regulatory substances. Following receptor activation, a series of events is set into motion that serves to transduce the information imparted to the target cell. Such transduction mechanisms are numerous, and may be excitatory or inhibitory to the cell depending upon which G-protein subunits the receptor is coupled.
Benamou AE, Marlin DJ, Callingham BC, Hiley RC, Lekeux R.There is currently little published information about the effects of endothelin-1 (ET-1), a potent endogenous spasmogen of vascular and airway smooth muscle, on pulmonary vasculature and airways or which ET receptor subtypes mediate ET-1-induced vasoconstrictive and bronchoconstrictive action in the horse. Objective: To investigate the effect of endothelin-1 (ET-1) on smooth muscle from isolated equine pulmonary artery and bronchus. In addition, the roles of ETA and ETB receptors in ET-1 mediated contraction in these tissues were assessed. Methods: The force generation of ring segments from pu...
Marti M, Mevissen M, Althaus H, Steiner A.The goal of this study was to investigate the effect of bethanechol (BeCh) on contractility patterns of smooth muscle preparations of equine duodenum descendens, jejunum, caecum and pelvic flexure in vitro. Concentration-response relationships were developed for BeCh using in vitro assays with and without preincubation of muscarinic (M) receptor antagonists for M2 and M3 receptors. BeCh induced a significant, concentration-dependent increase in contractile response in equine intestine in specimens with circular orientation. The maximal effect was largest for jejunal specimens with no differenc...
Prieto D, Arcos LR, Martínez P, Benedito S, García-Sacristán A, Hernández M.The distribution of neuropeptide Y (NPY)-immunorective nerves and the receptors involved in the effects of NPY upon electrical field stimulation (EFS)- and noradrenaline (NA)-elicited contractions were investigated in horse penile small arteries. NPY-immunoreactive nerves were widely distributed in the erectile tissues with a particularly high density around penile intracavernous small arteries. In small arteries isolated from the proximal part of the corpora cavernosa, NPY (30 nM) produced a variable modest enhancement of the contractions elicited by both EFS and NA. At the same concentration...
Katz LM, Marr CM, Elliott J.To compare the responses of equine digital arteries (EDAs) and equine digital veins (EDVs) to endothelin-1 (ET-1) and determine the role of the endothelium and type of receptors involved in the modulation and mediation of those responses, respectively. Methods: 5 to 9 palmar digital vessels/experiment from 28 healthy horses. Methods: Rings of dissected vessels were mounted under tension between force transducer wires in organ baths containing Krebs-Henseleit solution at 30 degrees C. Responses of EDAs and EDVs (with intact [+e] or denuded [-e] endothelium) to cumulative concentrations of ET-1 ...
Li CH, Ng TB, Yamashiro D, Chung D, Hammonds RG, Tseng LF.Beta-endorphin has been isolated from equine pituitaries. Its amino acid sequence is identical to that of ovine, bovine and camel beta-endorphins except for substitution of the threonine residue at position 6 by serine. The equine beta-endorphin has also been synthesized by the solid-phase method. In comparison with the human hormone, equine beta-endorphin was shown to possess 3 times the receptor-binding activity in rat membrane preparations and 1.6 times the analgesic potency in the mouse tail-flick assay.
Mißbach S, Aleksic D, Blaschke L, Hassemer T, Lee KJ, Mansfeld M, Hänske J, Handler J, Kammerer R.The CEA gene family is one of the most rapidly evolving gene families in the human genome. The founder gene of the family is thought to be an ancestor of the inhibitory immune checkpoint molecule CEACAM1. Comprehensive analyses of mammalian genomes showed that the CEA gene family is subject to tremendous gene family expansion and contraction events in different mammalian species. While in some species (e.g. rabbits) less than three CEACAM1 related genes exist, were in others (certain microbat species) up to 100 CEACAM1 paralogs identified. We have recently reported that the horse has also an e...
Prause AS, Guionaud CT, Stoffel MH, Portier CJ, Mevissen M.To evaluate the expression of the 5-hydroxytryptamine 4 (5-HT4) receptor subtype and investigate the modulating function of those receptors on contractility in intestinal tissues obtained from horses without gastrointestinal tract disease. Methods: Smooth muscle preparations from the duodenum, ileum, and pelvic flexure collected immediately after slaughter of 24 horses with no history or signs of gastrointestinal tract disease. Methods: In isometric organ baths, the contractile activities of smooth muscle preparations in response to 5-hydroxytryptamine and electric field stimulation were asses...
Treonze KM, Alves K, Fischer P, Hagmann WK, Hora D, Kulick A, Vakerich K, Smith ND, Lingham RB, Maniar S, Reger TS, Zunic J, Munoz B, Prasit P....The purpose of this study was to characterize the alpha(4)beta(1) receptor (CD49d/CD29, very late antigen-4, VLA-4) on circulating equine leukocytes and to evaluate the intrinsic potency of an alpha(4)beta(1) receptor antagonist (Compound B) in the horse. Ultimately, these studies would allow us to determine the suitability of treating recurrent airway obstruction (RAO; heaves) affected horses by blocking the cellular recruitment of lymphocytes and neutrophils into the lung. The data demonstrates the alpha(4)beta(1) integrin is present on horse lymphocytes and neutrophils (fluorescence-assiste...
Simmons TR, Cook JA, Moore JN, Halushka PV.Thromboxane (TX) A2 has been implicated as an important pathophysiologic mediator of a variety of cardiovascular diseases. Monocytes synthesize TXA2 and it modulates their function. This study sought to characterize monocyte TXA2 receptors. Radioligand binding studies were performed on membranes prepared from equine peripheral blood monocytes using [125I]BOP, a TXA2 receptor agonist. [125I]BOP bound to a single class of binding sites (Kd = 1.0 +/- 0.3 nM and Bmax = 389 +/- 191 fmol/mg protein; n = 5). Several TXA2 receptor agonists and antagonists competed for binding with [125I]BOP. I-BOP pro...
Miyamoto A, Obi T, Nishio A.The vasomotor effects of 5-hydroxytryptamine (5-HT) on isolated equine basilar arteries were studied. 5-HT induced contractions of equine basilar arteries in a concentration-dependent manner, with a pEC50 value (with 95% confidence limits) of 7.35 (7.08-7.62). Similar results were obtained with endothelium-denuded basilar arteries. Contractions were not competitively inhibited by the 5-HT2 receptor antagonist ketanserin at low concentrations of 5-HT. Conversely, at high concentrations of 5-HT, contractions were inhibited by ketanserin in a concentration-dependent manner, with a pA2 value of 8....
Bryant CE, Clarke KW.Spirals of endothelially denuded equine saphenous vein were used to study the pre- and post-junctional effects of medetomidine in vitro. The pD2 values were calculated for noradrenaline (6.7 +/- 0.1), phenylephrine (5.6 +/- 0.1), BHT 920 (6.2 +/- 0.2) and UK 14304 (5.7 +/- 0.2). Medetomidine produced a biphasic response, with a pD(2)1 of 8.2 +/- 0.1 and a pD(2)2 of 5.7 +/- 0.1 in the equine saphenous vein (n = 6). Prazosin (10(-7) M) significantly shifted the second phase of the medetomidine concentration-response curve to the right (pD(2)1 was 8.1 +/- 0.2 and pD(2)2 was 5.0 +/- 0.2, P < 0....
Martínez AC, Prieto D, Hernández M, García-Sacristán A, Benedito S.The present investigation was designed to evaluate the effect of histamine on isolated rings of horse deep dorsal penile vein. Under precontracted or basal conditions, histamine evoked an endothelium-independent contraction. Preincubation of the vein rings with the selective H1 receptor antagonist, mepyramine, shifted the concentration-response curve for histamine and to the H1 receptor agonist 2-pyridylethylamine to the right in a competitive manner. Pretreatment with cimetidine, a specific H2 receptor antagonist, did not modify the pEC50 and maximal contraction of the histamine response. Cim...
Deumer J, de Haan F, Tulp MT, van den Hoven R.The effects of an oral isoxsuprine-resin preparation on the blood flow in the thoracic limb of seven horses was determined by thermography. Treatment with the oral resin preparation resulted in increased skin temperatures compared with the non-medicated controls. The maximal temperature differences, 2.2 degrees C for the horses treated with 0.9 mg/kg and 1.8 degrees C for the horses treated with 1.2 mg/kg, occurred four hours after dosing. Plasma total isoxsuprine, determined in three horses, was detectable two hours after oral dosing and maximal eight hours after dosing, but free isoxsuprine ...
Nádasdi L, Yamashiro D, Li CH, Izdebski J.Five analogs of equine β-melanotropin have been synthesized by the solid phase method. The NH2-terminal aspartic acid was substituted with amino acids (Gly, Trp, Ile, Lys and Nα-acetyl-Asp) differing widely in physicochemical properties. On the basis of their lipolytic potencies it was concluded that this position plays a negligible role in this activity.
