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Urschel KL, McKenzie EC. Nutritional Influences on Skeletal Muscle and Muscular Disease. Vet Clin North Am Equine Pract 2021; 37:139-175. [PMID: 33820605 DOI: 10.1016/j.cveq.2020.12.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
Skeletal muscle comprises 40% to 55% of mature body weight in horses, and its mass is determined largely by rates of muscle protein synthesis. In order to support exercise, appropriate energy sources are essential: glucose can support both anaerobic and aerobic exercise, whereas fat can only be metabolized aerobically. Following exercise, ingestion of nonfiber carbohydrates and protein can aid muscle growth and recovery. Muscle glycogen replenishment is slow in horses, regardless of dietary interventions. Several heritable muscle disorders, including type 1 and 2 polysaccharide storage myopathy and recurrent exertional rhabdomyolysis, can be managed in part by restricting dietary nonstructural carbohydrate intake.
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Affiliation(s)
- Kristine L Urschel
- Department of Animal and Food Sciences, University of Kentucky, 612 W.P. Garrigus Building, Lexington, KY 40546, USA
| | - Erica C McKenzie
- Department of Clinical Sciences, Carlson College of Veterinary Medicine, Oregon State University, 227 Magruder Hall, 700 Southwest 30th Street, Corvallis, OR 97331, USA.
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Pathways of calcium regulation, electron transport, and mitochondrial protein translation are molecular signatures of susceptibility to recurrent exertional rhabdomyolysis in Thoroughbred racehorses. PLoS One 2021; 16:e0244556. [PMID: 33566847 PMCID: PMC7875397 DOI: 10.1371/journal.pone.0244556] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 12/13/2020] [Indexed: 12/13/2022] Open
Abstract
Recurrent exertional rhabdomyolysis (RER) is a chronic muscle disorder of unknown etiology in racehorses. A potential role of intramuscular calcium (Ca2+) dysregulation in RER has led to the use of dantrolene to prevent episodes of rhabdomyolysis. We examined differentially expressed proteins (DEP) and gene transcripts (DEG) in gluteal muscle of Thoroughbred race-trained mares after exercise among three groups of 5 horses each; 1) horses susceptible to, but not currently experiencing rhabdomyolysis, 2) healthy horses with no history of RER (control), 3) RER-susceptible horses treated with dantrolene pre-exercise (RER-D). Tandem mass tag LC/MS/MS quantitative proteomics and RNA-seq analysis (FDR <0.05) was followed by gene ontology (GO) and semantic similarity of enrichment terms. Of the 375 proteins expressed, 125 were DEP in RER-susceptible versus control, with 52 ↑DEP mainly involving Ca2+ regulation (N = 11) (e.g. RYR1, calmodulin, calsequestrin, calpain), protein degradation (N = 6), antioxidants (N = 4), plasma membranes (N = 3), glyco(geno)lysis (N = 3) and 21 DEP being blood-borne. ↓DEP (N = 73) were largely mitochondrial (N = 45) impacting the electron transport system (28), enzymes (6), heat shock proteins (4), and contractile proteins (12) including Ca2+ binding proteins. There were 812 DEG in RER-susceptible versus control involving the electron transfer system, the mitochondrial transcription/translational response and notably the pro-apoptotic Ca2+-activated mitochondrial membrane transition pore (SLC25A27, BAX, ATP5 subunits). Upregulated mitochondrial DEG frequently had downregulation of their encoded DEP with semantic similarities highlighting signaling mechanisms regulating mitochondrial protein translation. RER-susceptible horses treated with dantrolene, which slows sarcoplasmic reticulum Ca2+ release, showed no DEG compared to control horses. We conclude that RER-susceptibility is associated with alterations in proteins, genes and pathways impacting myoplasmic Ca2+ regulation, the mitochondrion and protein degradation with opposing effects on mitochondrial transcriptional/translational responses and mitochondrial protein content. RER could potentially arise from excessive sarcoplasmic reticulum Ca2+ release and subsequent mitochondrial buffering of excessive myoplasmic Ca2+.
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Sarcolipin Exhibits Abundant RNA Transcription and Minimal Protein Expression in Horse Gluteal Muscle. Vet Sci 2020; 7:vetsci7040178. [PMID: 33202832 PMCID: PMC7711957 DOI: 10.3390/vetsci7040178] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2020] [Accepted: 11/05/2020] [Indexed: 01/02/2023] Open
Abstract
Ca2+ regulation in equine muscle is important for horse performance, yet little is known about this species-specific regulation. We reported recently that horse encode unique gene and protein sequences for the sarcoplasmic reticulum (SR) Ca2+-transporting ATPase (SERCA) and the regulatory subunit sarcolipin (SLN). Here we quantified gene transcription and protein expression of SERCA and its inhibitory peptides in horse gluteus, as compared to commonly-studied rabbit skeletal muscle. RNA sequencing and protein immunoblotting determined that horse gluteus expresses the ATP2A1 gene (SERCA1) as the predominant SR Ca2+-ATPase isoform and the SLN gene as the most-abundant SERCA inhibitory peptide, as also found in rabbit skeletal muscle. Equine muscle expresses an insignificant level of phospholamban (PLN), another key SERCA inhibitory peptide expressed commonly in a variety of mammalian striated muscles. Surprisingly in horse, the RNA transcript ratio of SLN-to-ATP2A1 is an order of magnitude higher than in rabbit, while the corresponding protein expression ratio is an order of magnitude lower than in rabbit. Thus, SLN is not efficiently translated or maintained as a stable protein in horse muscle, suggesting a non-coding role for supra-abundant SLN mRNA. We propose that the lack of SLN and PLN inhibition of SERCA activity in equine muscle is an evolutionary adaptation that potentiates Ca2+ cycling and muscle contractility in a prey species domestically selected for speed.
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Uryash A, Flores V, Adams JA, Allen PD, Lopez JR. Memory and Learning Deficits Are Associated With Ca 2+ Dyshomeostasis in Normal Aging. Front Aging Neurosci 2020; 12:224. [PMID: 32765253 PMCID: PMC7378956 DOI: 10.3389/fnagi.2020.00224] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2020] [Accepted: 06/23/2020] [Indexed: 12/12/2022] Open
Abstract
Neuronal intracellular Ca2+ homeostasis is critical to the normal physiological functions of neurons and neuronal Ca2+ dyshomeostasis has been associated with the age-related decline of cognitive functions. Accumulated evidence indicates that the underlying mechanism for this is that abnormal intracellular Ca2+ levels stimulate the dysregulation of intracellular signaling, which subsequently induces neuronal cell death. We examined intracellular Ca2+ homeostasis in cortical (in vivo) and hippocampal (in vitro) neurons from young (3-months), middle-age (12-months), and aged (24-months) wild type C57BL6J mice. We found a progressive age-related elevation of intracellular resting calcium ([Ca2+]r) in cortical (in vivo) and hippocampal (in vitro) neurons associated with increased hippocampal neuronal calpain activity and reduced cell viability. In vitro, removal of extracellular Ca2+ or treatment with SAR7334 or dantrolene reduced [Ca2+]r in all age groups and dantrolene treatment lowered calpain activity and increased cell viability. In vivo, both middle-aged and aged mice showed cognitive deficits compared to young mice, which improved after dantrolene treatment. These findings support the hypothesis that intracellular Ca2+ dyshomeostasis is a major mechanism underlying the cognitive deficits seen in both normal aging and degenerative neurologic diseases.
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Affiliation(s)
- Arkady Uryash
- Division of Neonatology, Mount Sinai Medical Center, Miami, FL, United States
| | - Valentina Flores
- Department of Research, Mount Sinai Medical Center, Miami, FL, United States
| | - Jose A. Adams
- Division of Neonatology, Mount Sinai Medical Center, Miami, FL, United States
| | - Paul D. Allen
- Malignant Hyperthermia Investigation Unit, St James’ University Hospital, University of Leeds, Leeds, United Kingdom
| | - Jose R. Lopez
- Department of Research, Mount Sinai Medical Center, Miami, FL, United States
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Breed D, Meyer LCR, Steyl JCA, Goddard A, Burroughs R, Kohn TA. Conserving wildlife in a changing world: Understanding capture myopathy-a malignant outcome of stress during capture and translocation. CONSERVATION PHYSIOLOGY 2019; 7:coz027. [PMID: 31304016 PMCID: PMC6612673 DOI: 10.1093/conphys/coz027] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/24/2018] [Revised: 04/22/2019] [Accepted: 05/03/2019] [Indexed: 05/18/2023]
Abstract
The number of species that merit conservation interventions is increasing daily with ongoing habitat destruction, increased fragmentation and loss of population connectivity. Desertification and climate change reduce suitable conservation areas. Physiological stress is an inevitable part of the capture and translocation process of wild animals. Globally, capture myopathy-a malignant outcome of stress during capture operations-accounts for the highest number of deaths associated with wildlife translocation. These deaths may not only have considerable impacts on conservation efforts but also have direct and indirect financial implications. Such deaths usually are indicative of how well animal welfare was considered and addressed during a translocation exercise. Importantly, devastating consequences on the continued existence of threatened and endangered species succumbing to this known risk during capture and movement may result. Since first recorded in 1964 in Kenya, many cases of capture myopathy have been described, but the exact causes, pathophysiological mechanisms and treatment for this condition remain to be adequately studied and fully elucidated. Capture myopathy is a condition with marked morbidity and mortality that occur predominantly in wild animals around the globe. It arises from inflicted stress and physical exertion that would typically occur with prolonged or short intense pursuit, capture, restraint or transportation of wild animals. The condition carries a grave prognosis, and despite intensive extended and largely non-specific supportive treatment, the success rate is poor. Although not as common as in wildlife, domestic animals and humans are also affected by conditions with similar pathophysiology. This review aims to highlight the current state of knowledge related to the clinical and pathophysiological presentation, potential treatments, preventative measures and, importantly, the hypothetical causes and proposed pathomechanisms by comparing conditions found in domestic animals and humans. Future comparative strategies and research directions are proposed to help better understand the pathophysiology of capture myopathy.
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Affiliation(s)
- Dorothy Breed
- Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa
- Biodiversity Management Branch, Environmental Management Department, City of Cape Town, Maitland, South Africa
| | - Leith C R Meyer
- Department of Paraclinical Sciences, University of Pretoria, Onderstepoort, South Africa
- Centre for Veterinary Wildlife Studies, University of Pretoria, Onderstepoort, South Africa
| | - Johan C A Steyl
- Department of Paraclinical Sciences, University of Pretoria, Onderstepoort, South Africa
- Centre for Veterinary Wildlife Studies, University of Pretoria, Onderstepoort, South Africa
| | - Amelia Goddard
- Department of Companion Animal Clinical Studies, University of Pretoria, Onderstepoort, South Africa
- Centre for Veterinary Wildlife Studies, University of Pretoria, Onderstepoort, South Africa
| | - Richard Burroughs
- Department of Production Animal Studies, University of Pretoria, Onderstepoort, South Africa
- Centre for Veterinary Wildlife Studies, University of Pretoria, Onderstepoort, South Africa
- Mammal Research Institute, University of Pretoria, Onderstepoort, South Africa
| | - Tertius A Kohn
- Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Cape Town, South Africa
- Department of Paraclinical Sciences, University of Pretoria, Onderstepoort, South Africa
- Corresponding author: Division of Exercise Science and Sports Medicine, Department of Human Biology, University of Cape Town, Boundary Road, Cape Town 7725, South Africa. Tel.: +27 21 406 6235;
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Bowden GD, Land KM, O'Connor RM, Fritz HM. High-throughput screen of drug repurposing library identifies inhibitors of Sarcocystis neurona growth. INTERNATIONAL JOURNAL FOR PARASITOLOGY-DRUGS AND DRUG RESISTANCE 2018; 8:137-144. [PMID: 29547840 PMCID: PMC6114104 DOI: 10.1016/j.ijpddr.2018.02.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 01/29/2018] [Accepted: 02/15/2018] [Indexed: 01/26/2023]
Abstract
The apicomplexan parasite Sarcocystis neurona is the primary etiologic agent of equine protozoal myeloencephalitis (EPM), a serious neurologic disease of horses. Many horses in the U.S. are at risk of developing EPM; approximately 50% of all horses in the U.S. have been exposed to S. neurona and treatments for EPM are 60-70% effective. Advancement of treatment requires new technology to identify new drugs for EPM. To address this critical need, we developed, validated, and implemented a high-throughput screen to test 725 FDA-approved compounds from the NIH clinical collections library for anti-S. neurona activity. Our screen identified 18 compounds with confirmed inhibitory activity against S. neurona growth, including compounds active in the nM concentration range. Many identified inhibitory compounds have well-defined mechanisms of action, making them useful tools to study parasite biology in addition to being potential therapeutic agents. In comparing the activity of inhibitory compounds identified by our screen to that of other screens against other apicomplexan parasites, we found that most compounds (15/18; 83%) have activity against one or more related apicomplexans. Interestingly, nearly half (44%; 8/18) of the inhibitory compounds have reported activity against dopamine receptors. We also found that dantrolene, a compound already formulated for horses with a peak plasma concentration of 37.8 ± 12.8 ng/ml after 500 mg dose, inhibits S. neurona parasites at low concentrations (0.065 μM [0.036-0.12; 95% CI] or 21.9 ng/ml [12.1-40.3; 95% CI]). These studies demonstrate the use of a new tool for discovering new chemotherapeutic agents for EPM and potentially providing new reagents to elucidate biologic pathways required for successful S. neurona infection.
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Affiliation(s)
- Gregory D Bowden
- Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA, USA
| | - Kirkwood M Land
- Department of Biological Sciences, University of the Pacific, Stockton, CA, USA
| | - Roberta M O'Connor
- Department of Veterinary Microbiology and Pathology, College of Veterinary Medicine, Washington State University, Pullman, WA, USA.
| | - Heather M Fritz
- Department of Pathology, Microbiology and Immunology, School of Veterinary Medicine, University of California Davis, Davis, CA, USA.
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McKenzie E. Current status of myopathies affecting athletic horses. COMPARATIVE EXERCISE PHYSIOLOGY 2017. [DOI: 10.3920/cep170005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Muscular disorders rank among the most prevalent problems of horses competing in a broad variety of athletic disciplines, including track racing, dressage, endurance racing and Western riding disciplines. As described in this review, active scientific investigation is continuing to elucidate the different mechanisms underlying specific muscular disorders in horses, and is discovering and defining new disorders, and new methods of diagnosis, treatment and management. The flourishing field of equine rehabilitation and regenerative medicine is also driving the progressive application of a variety of modalities to the treatment and management of musculoskeletal conditions in horses. However, it is essential that this be accompanied by appropriate scientific investigation to verify the efficacy of recommended modalities and treatment protocols.
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Affiliation(s)
- E. McKenzie
- Department of Clinical Sciences, College of Veterinary Medicine, Oregon State University, 227 Magruder Hall, Corvallis, OR 97331, USA
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Scalco RS, Voermans NC, Piercy RJ, Jungbluth H, Quinlivan R. Dantrolene as a possible prophylactic treatment for RYR1-related rhabdomyolysis. Eur J Neurol 2016; 23:e56-7. [PMID: 27431030 DOI: 10.1111/ene.13051] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Accepted: 04/21/2016] [Indexed: 11/28/2022]
Affiliation(s)
- R S Scalco
- MRC Centre for Neuromuscular Diseases, UCL, London, UK
| | - N C Voermans
- Department of Neurology, Radboud University Medical Centre, Nijmegen, The Netherlands
| | - R J Piercy
- Comparative Neuromuscular Diseases Laboratory, Royal Veterinary College, London
| | - H Jungbluth
- Department of Clinical and Basic Neuroscience, IoPPN, King's College, UK
| | - R Quinlivan
- MRC Centre for Neuromuscular Diseases, UCL, London, UK
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Abstract
Horses are remarkable athletes and a fascinating species in which to study the genetic bases of athletic performance, skeletal muscle biology, and neuromuscular disease. Genetic selection in horses has resulted in many breeds that possess anatomical, physiological, and metabolic variations linked to speed, power, and endurance that are beginning to be defined at the molecular level. Along with the concentration of positive traits, equine breeding programs have also inadvertently concentrated heritable muscle diseases for which mutations impacting electrical conduction, muscle contraction, and energy metabolism within and across breeds have been characterized. The study of heritable muscle diseases in horses has provided exciting insights into the normal structure and function of muscle and important diagnostic tools for veterinarians. Results empower breeders and breed associations to make difficult decisions about how to use this information to improve the overall health and well-being of horses.
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Affiliation(s)
- James R Mickelson
- College of Veterinary Medicine, University of Minnesota, St. Paul, Minnesota 55108; ,
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MCGowan CM. Science in brief: Clinical news from the 8th ICEEP conference 2010. Special topics. Equine Vet J 2012; 44:254-7. [DOI: 10.1111/j.2042-3306.2011.00537.x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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James RS, Walter I, Seebacher F. Variation in expression of calcium-handling proteins is associated with inter-individual differences in mechanical performance of rat (Rattus norvegicus) skeletal muscle. J Exp Biol 2011; 214:3542-8. [DOI: 10.1242/jeb.058305] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
SUMMARY
An important constraint on locomotor performance is the trade-off between sprint and endurance performance. One intuitive explanation for this trade-off is that an individual muscle cannot excel at generating both maximal force/power and high fatigue resistance. The underlying reasons for this muscle trade-off are poorly defined. The aim of this study was to test the hypothesis that inter-individual variation in muscle mechanics is associated with inter-individual differences in metabolic capacities and expression of calcium-handling proteins. Lateral gastrocnemius muscles were isolated from 20 rats (Rattus norvegicus) and analysed to determine metabolic capacity, sarco/endoplasmic reticulum calcium ATPase (SERCA)1 protein concentration, total SERCA activity, and mRNA concentrations of SERCA1, SERCA2, troponin I and ryanodine receptors. Isometric studies of lateral gastrocnemius muscles at 30°C showed that muscles with higher sprint performance had lower fatigue resistance. More rapid muscle contraction was correlated with higher lactate dehydrogenase activity and increased expression of ryanodine receptor 1. More rapid muscle relaxation was correlated with increased expression of troponin I type 2 (fast) isoform and decreased expression of SERCA2 (slow) isoform. Treating muscles with dantrolene confirmed that ryanodine receptor activity is important in determining tetanus force and muscle contraction rates, but has no effect on fatigue resistance. Thapsigargin treatment revealed that SERCA activity determines fatigue resistance but does not affect maximal muscle force or contraction rates. We conclude that the opposing roles of SERCA activity and expression of ryanodine receptors in determining fatigue resistance and force production, respectively, at least partly explain differences in sprint and endurance performance in isolated rat gastrocnemius muscle.
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Affiliation(s)
- Rob S. James
- Department of Biomolecular and Sport Sciences, Coventry University, Coventry CV1 5FB, UK
| | - Isabel Walter
- Integrative Physiology, School of Biological Sciences, University of Sydney, NSW 2006, Australia
| | - Frank Seebacher
- Integrative Physiology, School of Biological Sciences, University of Sydney, NSW 2006, Australia
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DiMAIO KNYCH HK, ARTHUR RM, TAYLOR A, MOELLER BC, STANLEY SD. Pharmacokinetics and metabolism of dantrolene in horses. J Vet Pharmacol Ther 2011; 34:238-46. [DOI: 10.1111/j.1365-2885.2010.01214.x] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Mc KENZIE EC, GARRETT RL, PAYTON ME, RIEHL JH, FIRSHMAN AM, VALBERG SJ. Effect of feed restriction on plasma dantrolene concentrations in horses. Equine Vet J 2010:613-7. [DOI: 10.1111/j.2042-3306.2010.00262.x] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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Marr CM, Newton JR. Clinical Evidence Articles in Equine Veterinary Journal: progress since inception. Equine Vet J 2010; 38:110-2. [PMID: 16536378 DOI: 10.2746/042516406776563224] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Affiliation(s)
- C M Marr
- Rossdales Equine Hospital, Cotton End Road, Exning, Newmarket, Suffolk, UK
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Schultz CL, Lodge-Ivey SL, Bush LP, Craig AM, Strickland JR. Effects of initial and extended exposure to an endophyte-infected tall fescue seed diet on faecal and urinary excretion of ergovaline and lysergic acid in mature geldings. N Z Vet J 2006; 54:178-84. [PMID: 16915339 DOI: 10.1080/00480169.2006.36692] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
AIM To determine the amount of ergovaline and lysergic acid retained or excreted by geldings fed endophyte-infected seed containing known concentrations of these alkaloids, and the effects of exposure time on clinical expression of toxicosis. METHODS Mature geldings (n=10) received diets containing either endophyte-free (E-) or endophyte-infected (E+) tall fescue seed during three experimental phases. The first phase (Days -14 to -1) was an adaptation phase, to allow all horses to adapt to a diet containing E- tall fescue seed. The second (Days 0 to 3) was the initial exposure phase to E+ tall fescue seed, used for the delivery of ergovaline and lysergic acid at 0.5 and 0.3 mg/kg of diet, respectively, to test the initial effects of exposure on routes and amounts of elimination of alkaloid. During this phase, half the geldings were exposed to an E+ diet while the rest served as controls by remaining on the E- diet. Once assigned to treatments, geldings remained on the same diet through the third phase (Days 4 to 21), which served as the extended exposure phase. Total outputs of faeces and urine were collected within each phase, to determine retention of ergovaline and lysergic acid and nutrient digestibility. Serum was collected weekly and analysed for activities of enzymes and concentrations of prolactin. Bodyweights (BW) and rectal temperatures were recorded weekly. RESULTS BW, rectal temperature, enzyme activities and concentrations of prolactin in serum, and nutrient digestibility were not affected by treatment. Total intake of ergovaline by geldings on the E+ diet was 3.5 and 3.6 (SE 0.20) mg/day, and 2.1 and 2.3 (SE 0.11) mg/day were not accounted for in initial and extended phases, respectively. Lysergic acid was excreted in the urine (4.0 and 4.9 (SE 0.97) mg/day) and faeces (2.5 and 2.7 (SE 0.35) mg/day) at greater amounts than that consumed (2.0 and 1.9 (SE 0.09) mg/day) during the initial and extended exposure phases, respectively. Animals exposed to E+ seed for a period of 20 days appeared to excrete more (1.5 vs 1.2 mg/day; SE 0.08; p=0.03) ergovaline in the faeces than those exposed for only 4 days. CONCLUSIONS Exposure time to the ergot alkaloids had a limited effect on the route of elimination or the amounts of ergovaline or lysergic acid excreted by horses. The primary alkaloid excreted was lysergic acid, and urine was the major route of elimination. These data will aid future research to improve animals' tolerance to toxic endophyte-infected tall fescue.
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Affiliation(s)
- C L Schultz
- USDA, ARS Southern Plains Agricultural Center, 2881 F&B Road, College Station, TX 77845, USA
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Abstract
Since riders nowadays are expecting the highest level of performance from their horses, muscular disorders therefore represent a major problem for the equine athlete. A lot of research has been done to identify muscular disorders and their etiopathogenesis. Both acquired and inherited forms of muscle diseases have been described. In this review only the latter forms will be mentioned. Major signs of all muscle disorders are muscular stiffness, cramping or pain, muscular fasciculations, muscular atrophy and exercise intolerance. Muscle biopsies can help to identify the cause of rhabdomyolysis or muscular atrophy. However, especially in hereditary muscular diseases, a lot of questions are still to be answered. Increasing knowledge of the etiopathogenesis and newer diagnostic tests may lead to a more accurate diagnosis of the individual diseases in future.
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Affiliation(s)
- H Nollet
- Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, University of Ghent, Merelbeke, Belgium.
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