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Stefaniuk-Szmukier M, Piórkowska K, Ropka-Molik K. Equine Metabolic Syndrome: A Complex Disease Influenced by Multifactorial Genetic Factors. Genes (Basel) 2023; 14:1544. [PMID: 37628596 PMCID: PMC10454496 DOI: 10.3390/genes14081544] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Revised: 07/10/2023] [Accepted: 07/26/2023] [Indexed: 08/27/2023] Open
Abstract
Equine metabolic syndrome (EMS) has become an important issue in modern veterinary medicine and is linked to the common, extremely painful, most-of-the-time performance-terminating hoof laminitis. The growing knowledge in the field of genetic background, inducing environmental factors, diagnosis, treatment and maintenance of affected equines led us to summarise the available information to be used not only for scientific purposes but for fieldwork. In horses, the clinical presentation of EMS includes: obesity or local fat deposition, bilateral lameness or hoof rings attributed to ongoing or previous (pasted) laminitis with the key feature of the occurrence of insulin dysregulation, disturbing the homeostasis within insulin, glucose and lipid metabolism. The management of EMS is based on dietary and fitness discipline; however, intensive research is ongoing in the field of regenerative medicine to develop modern and promising therapies.
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Affiliation(s)
- Monika Stefaniuk-Szmukier
- Department of Animal Molecular Biology, National Research Institute of Animal Production, Krakowska 1, 32-083 Balice, Poland
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2
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Burns TA. "Feeding the Foot": Nutritional Influences on Equine Hoof Health. Vet Clin North Am Equine Pract 2021; 37:669-684. [PMID: 34674915 DOI: 10.1016/j.cveq.2021.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022] Open
Abstract
Nutrition plays an important role in equine health, including that of the foot. Deficiencies and excesses of dietary components can affect the growth and function of the foot and have been associated with important podiatric diseases. The recognition, prevention, and treatment of specific notable nutritional diseases of the foot are discussed, as well as information regarding specific ingredients included in supplements meant to improve equine hoof quality. Ensuring provision of a balanced diet, maintaining horses in appropriate body condition, and seeking guidance from an equine nutritionist when creating dietary recommendations will prevent most equine foot disease related to nutrition.
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Affiliation(s)
- Teresa A Burns
- Department of Veterinary Clinical Sciences, The Ohio State University, Columbus, OH, USA.
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Li YP, Ding JF, Abid HM, Zhang XH, Li SC, Song QZ, Jiang LH, Zhang JT, Wang HB. Oral oligofructose challenge reduces expression of glucose transport-1 and 5'-adenosine monophosphate-activated protein kinase in lamellar wall of Holstein heifer claw. Res Vet Sci 2021; 141:42-47. [PMID: 34662833 DOI: 10.1016/j.rvsc.2021.10.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2019] [Revised: 09/15/2021] [Accepted: 10/05/2021] [Indexed: 11/28/2022]
Abstract
The laminar tissue of bovine laminitis may undergo energy failure. The expression of glucose transport protein-1 (GLUT-1) and 5'-adenosine monophosphate-activated protein kinase (AMPK) affects the energy metabolism of digital laminar tissue. This study aimed to determine the expression of glucose uptake and AMPK in laminar wall corium of Holstein heifer claw by oral administration of oligofructose. A total of twelve clinically healthy Holstein heifers were selected and divided into two groups, including control (CON, n = 6) and experimental (OF, n = 6) groups. The heifers of OF group were given 17 g/kg BW oligofructose dissolved in water (20 mL/kg BW) and the heifers of CON group were given water only (20 mL/kg BW). The laminar tissues were collected after euthanasia. The amount of protein and transcript expression of AMPK and GLUT-1 were determined by western blot and quantitative reverse transcription-polymerase chain reaction (qRT-PCR), respectively. Expressions of phosphoenolpyruvate carboxy-kinase (PEPCK), receptor-c coactivator1-α (PGC-1α) and peroxisome proliferator-activated receptor-γ (PPAR-γ) were determined by qRT-PCR. The heifers of OF group showed no significant change in the expression and concentration of AMPK. The phosphor-(Thr172) AMPK and GLUT-1 were significantly decreased, while the gene contents of PPAR-γ and PGC-1α were significantly increased. The activation of AMPK and GLUT-1 in digital laminar tissues of heifers was inhibited, which may contribute to digital laminar tissue damage.
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Affiliation(s)
- Y P Li
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China; Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, Harbin 150030, PR China
| | - J F Ding
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China; Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, Harbin 150030, PR China
| | - H M Abid
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China; Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, Harbin 150030, PR China
| | - X H Zhang
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China; Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, Harbin 150030, PR China
| | - S C Li
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China; Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, Harbin 150030, PR China
| | - Q Z Song
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China; Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, Harbin 150030, PR China
| | - L H Jiang
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China; Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, Harbin 150030, PR China
| | - J T Zhang
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China; Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, Harbin 150030, PR China
| | - H B Wang
- Department of Veterinary Surgery, College of Veterinary Medicine, Northeast Agricultural University, Harbin 150030, PR China; Heilongjiang Key Laboratory for Laboratory Animals and Comparative Medicine, Harbin 150030, PR China.
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Galantino-Homer H, Brooks SA. Genetics and Signaling Pathways of Laminitis. Vet Clin North Am Equine Pract 2020; 36:379-394. [PMID: 32654786 DOI: 10.1016/j.cveq.2020.04.001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Laminitis is a devastating disease with diverse etiologies and few, if any, effective treatments. Gene expression and hypothesis-generating genomic studies have provided a fresh look at the key molecular players at crucial timepoints in diverse experimental and naturally affected tissues. We summarize findings to date, and propose a unifying model of the laminitis disease process that includes several pathogenesis concepts shared with other diseases of epidermal and epithelial tissues. The value of these new pathways as potential therapeutic targets is exciting but will require careful future work to validate new methods and launch systematic clinical trials.
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Affiliation(s)
- Hannah Galantino-Homer
- Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, PA, USA
| | - Samantha A Brooks
- Department of Animal Sciences, UF Genetics Institute, University of Florida, Gainesville, FL, USA.
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Stokes SM, Burns TA, Watts MR, Bertin FR, Stefanovski D, Medina-Torres CE, Belknap JK, van Eps AW. Effect of digital hypothermia on lamellar inflammatory signaling in the euglycemic hyperinsulinemic clamp laminitis model. J Vet Intern Med 2020; 34:1606-1613. [PMID: 32583504 PMCID: PMC7379000 DOI: 10.1111/jvim.15835] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 06/03/2020] [Accepted: 06/03/2020] [Indexed: 12/25/2022] Open
Abstract
Background Continuous digital hypothermia (CDH) prevents lamellar failure in the euglycemic hyperinsulinemic clamp (EHC) model of laminitis, but the protective mechanisms are unclear. Hypothesis/Objectives To determine if CDH inhibits lamellar inflammatory signaling in the EHC model of laminitis. Animals Eight Standardbred horses. Methods Prospective experimental study. Horses underwent an EHC, with 1 forelimb treated with CDH and the other kept at ambient temperature (AMB). Horses were euthanized 48 hours after initiation of the EHC and lamellar tissue was analyzed via polymerase chain reaction (pro‐inflammatory cytokine and chemokine genes—CXCL1, CXCL6, CXCL8, IL‐6, MCP‐1, MCP‐2, IL‐1β, IL‐11, cyclooxygenase 1 and 2, tumour necrosis factor‐alpha [TNF‐α], E‐selectin, and intercellular adhesion molecule‐1 [ICAM‐1]) and immunoblotting (phosphorylated and total signal transducer and activator of transcription 1 [STAT1] and STAT3). Results Compared to AMB, lamellar messenger ribonucleic acid (mRNA) concentrations of CXCL6 (P =.02), CXCL8 (P = .008), IL‐6 (P = .008), IL‐1β (P = .008), IL‐11 (P = .008), and cyclooxygenase‐2 (P = .008) were decreased in CDH. Cyclooxygenase‐1 (P = .008) was increased in CDH, while CXCL1 (P = .15), MCP‐1 (P = .05), MCP‐2 (P = .46), TNF‐α (P = .05), E‐selectin (P = .15), and ICAM‐1 (P = .15) mRNA were not significantly different. Compared to AMB, lamellar concentration of total STAT3 protein was decreased in CDH (P < .001), but there was no change in phosphorylated STAT3 (P‐STAT3 [S727] P = .19; P‐STAT3 [Y705] P = .05). There was no change in lamellar concentrations of total STAT1 (P = .75) or phosphorylated STAT1 (P‐STAT1 [S727], P = .25; P‐STAT1 [Y701], P = .64). Conclusions and Clinical Importance These data add further support for the use of CDH as a first aid treatment for severe acute laminitis associated with hyperinsulinemia in horses.
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Affiliation(s)
- Simon M Stokes
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Teresa A Burns
- Department of Veterinary Clinical Sciences, The Ohio State University College of Veterinary Medicine, Columbus, Ohio, USA
| | - Mauria R Watts
- Department of Veterinary Clinical Sciences, The Ohio State University College of Veterinary Medicine, Columbus, Ohio, USA
| | - François-René Bertin
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Darko Stefanovski
- New Bolton Center, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA
| | - Carlos E Medina-Torres
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - James K Belknap
- Department of Veterinary Clinical Sciences, The Ohio State University College of Veterinary Medicine, Columbus, Ohio, USA
| | - Andrew W van Eps
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia.,New Bolton Center, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania, USA
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Stokes SM, Bertin FR, Stefanovski D, Belknap JK, Medina-Torres CE, Pollitt CC, van Eps AW. Lamellar energy metabolism and perfusion in the euglycaemic hyperinsulinaemic clamp model of equine laminitis. Equine Vet J 2020; 52:577-584. [PMID: 31845378 DOI: 10.1111/evj.13224] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2019] [Revised: 10/29/2019] [Accepted: 12/04/2019] [Indexed: 01/19/2023]
Abstract
BACKGROUND Hyperinsulinaemia is associated with the development of endocrinopathic laminitis; however, the mechanisms remain unclear. OBJECTIVES Evaluate the effects of hyperinsulinaemia on lamellar energy metabolism and perfusion during laminitis development. STUDY DESIGN In vivo experiment. METHODS Eight Standardbred horses were instrumented with a microdialysis probe in the lamellae of a forelimb. A 24 hours baseline period (BASELINE) was followed by 48 hours of a continuous euglycaemic hyperinsulinaemic clamp (EHC) from 24 to 72 hours (CLAMP). Microdialysate was collected every 6 hours and analysed for glucose, lactate and pyruvate concentrations and lactate-to-pyruvate ratio (L:P). Microdialysis urea clearance was used to estimate lamellar tissue perfusion. Archived microdialysis samples from six identically instrumented Standardbred horses served as controls (CON). Variables were compared over time and between EHC and CON horses using a mixed-effects linear regression model. RESULTS Glucose concentration decreased during the CLAMP period in CON and EHC horses (P < .001), but there was no difference between CON and EHC (P > .9). Lactate concentration increased during the CLAMP period in CON and EHC horses (P < .001), however, the rate of increase was significantly higher in EHC horses relative to CON (P = .014). There was a relative increase in pyruvate concentration in EHC horses compared with CON during the CLAMP period (P = .03). L:P increased significantly in CON horses during the CLAMP period (P < .001) but not in EHC (P = .1). Urea clearance did not change in CON (P = .9) or EHC (P = .05) during the CLAMP, but did increase in EHC relative to CON (P = .02). MAIN LIMITATIONS The effects of microdialysis probe implantation on perfusion and metabolism remain unclear. The EHC model may not mimic natural endocrinopathic laminitis. CONCLUSIONS Laminitis developed without evidence of lamellar hypoperfusion or energy stress. Therapies to improve perfusion are unlikely to affect the initial development of endocrinopathic laminitis.
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Affiliation(s)
- Simon M Stokes
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Qld, Australia
| | - Francois R Bertin
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Qld, Australia
| | - Darko Stefanovski
- New Bolton Center, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania
| | - James K Belknap
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, Ohio
| | - Carlos E Medina-Torres
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Qld, Australia
| | - Christopher C Pollitt
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Qld, Australia
| | - Andrew W van Eps
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Qld, Australia.,New Bolton Center, Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Kennett Square, Pennsylvania
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Are There Shared Mechanisms in the Pathophysiology of Different Clinical Forms of Laminitis and What Are the Implications for Prevention and Treatment? Vet Clin North Am Equine Pract 2019; 35:379-398. [PMID: 31126692 DOI: 10.1016/j.cveq.2019.04.001] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
Laminitis is a consequence of primary disease processes elsewhere in the body. The key pathophysiologic events are insulin dysregulation in endocrinopathic laminitis, ischemia in supporting limb laminitis, and inflammation in sepsis-related laminitis. These apparently disparate mechanisms converge to cause lamellar attachment failure through epithelial cell adhesion loss and stretch, possibly mediated by common growth factor signaling pathways. Tissue damage through mechanical distraction, inflammation, pain, and a proliferative epithelial healing response are features of acute laminitis regardless of the cause. Preventive and treatment strategies based on knowledge of these unique and common mechanistic events are likely to improve clinical outcomes.
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Watts MR, Hegedus OC, Eades SC, Belknap JK, Burns TA. Association of sustained supraphysiologic hyperinsulinemia and inflammatory signaling within the digital lamellae in light-breed horses. J Vet Intern Med 2019; 33:1483-1492. [PMID: 30912229 PMCID: PMC6524466 DOI: 10.1111/jvim.15480] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2018] [Accepted: 03/05/2019] [Indexed: 12/24/2022] Open
Abstract
Background Hyperinsulinemia is associated with equine laminitis, and digital lamellar inflammation in equine metabolic syndrome‐associated laminitis (EMSAL) is modest when compared with sepsis‐associated laminitis. Objectives To characterize digital lamellar inflammation in horses in a euglycemic‐hyperinsulinemic clamp (EHC) model of laminitis. Animals Sixteen healthy adult Standardbred horses. Methods Prospective experimental study. Horses underwent EHC or saline infusion (CON) for 48 hours or until the onset of Obel grade 1 laminitis. Horses were euthanized, and digital lamellar tissue was collected and analyzed via polymerase chain reaction (pro‐inflammatory cytokine and chemokine genes—CXCL1, CXCL6, CXCL8, IL‐6, MCP‐1, MCP‐2, IL‐1β, IL11, cyclooxygenases 1 and 2, tumor necrosis factor alpha [TNF‐α], E‐selectin, and ICAM‐1), immunoblotting (phosphorylated and total signal transducer and activator of transcription 1 [STAT1], STAT3, and p38MAPK), and immunohistochemistry (markers of leukocyte infiltration: CD163, MAC387). Results Lamellar mRNA concentrations of IL‐1β, IL‐6, IL‐11, COX‐2, and E‐selectin were increased; the concentration of COX‐1 was decreased; and concentrations of CXCL1, CXCL6, MCP‐1, MCP‐2, IL‐8, TNF‐α and ICAM‐1 were not significantly different in the EHC group compared to the CON group (P ≤ .003). Lamellar concentrations of phosphorylated STAT proteins (P‐STAT1 [S727], P‐STAT1 [Y701], P‐STAT3 [S727], and P‐STAT3 [Y705]) were increased in the EHC group compared to the CON group, with phosphorylated STAT3 localizing to nuclei of lamellar basal epithelial cells. There was no change in the lamellar concentration of P‐p38 MAPK (T180/Y182), but the concentration of total p38 MAPK was decreased in the EHC samples. There was no evidence of notable lamellar leukocyte emigration. Conclusions and Clinical Importance These results establish a role for lamellar inflammatory signaling under conditions associated with EMSAL.
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Affiliation(s)
- Mauria R Watts
- Department of Veterinary Clinical Sciences, The Ohio State University College of Veterinary Medicine, Columbus, Ohio
| | - Olivia C Hegedus
- Department of Veterinary Clinical Sciences, The Ohio State University College of Veterinary Medicine, Columbus, Ohio
| | - Susan C Eades
- Department of Large Animal Clinical Sciences, Texas A&M University College of Veterinary Medicine and Biomedical Sciences, College Station, Texas
| | - James K Belknap
- Department of Veterinary Clinical Sciences, The Ohio State University College of Veterinary Medicine, Columbus, Ohio
| | - Teresa A Burns
- Department of Veterinary Clinical Sciences, The Ohio State University College of Veterinary Medicine, Columbus, Ohio
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Durham AE, Frank N, McGowan CM, Menzies-Gow NJ, Roelfsema E, Vervuert I, Feige K, Fey K. ECEIM consensus statement on equine metabolic syndrome. J Vet Intern Med 2019; 33:335-349. [PMID: 30724412 PMCID: PMC6430910 DOI: 10.1111/jvim.15423] [Citation(s) in RCA: 135] [Impact Index Per Article: 27.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2018] [Accepted: 01/11/2019] [Indexed: 12/26/2022] Open
Abstract
Equine metabolic syndrome (EMS) is a widely recognized collection of risk factors for endocrinopathic laminitis. The most important of these risk factors is insulin dysregulation (ID). Clinicians and horse owners must recognize the presence of these risk factors so that they can be targeted and controlled to reduce the risk of laminitis attacks. Diagnosis of EMS is based partly on the horse's history and clinical examination findings, and partly on laboratory testing. Several choices of test exist which examine different facets of ID and other related metabolic disturbances. EMS is controlled mainly by dietary strategies and exercise programs that aim to improve insulin regulation and decrease obesity where present. In some cases, pharmacologic aids might be useful. Management of an EMS case is a long‐term strategy requiring diligence and discipline by the horse's carer and support and guidance from their veterinarians.
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Affiliation(s)
| | - Nicholas Frank
- Department of Clinical Sciences, Cummings School of Veterinary Medicine at Tufts University, North Grafton, Massachusetts
| | - Cathy M McGowan
- Institute of Veterinary Science, University of Liverpool, Neston, United Kingdom
| | - Nicola J Menzies-Gow
- Department of clinical sciences and services, Royal Veterinary College, Herts, United Kingdom
| | - Ellen Roelfsema
- Department of Equine Sciences, Utrecht University, Utrecht, The Netherlands
| | - Ingrid Vervuert
- Faculty of Veterinary Medicine, University of Leipzig, Institute of Animal Nutrition, Nutrition Diseases and Dietetics, Leipzig, Germany
| | - Karsten Feige
- Clinic for Horses, University of Veterinary Medicine Hannover, Germany
| | - Kerstin Fey
- Equine Clinic, Internal Medicine, Faculty of Veterinary Medicine, Justus-Liebig-University of Giessen, Giessen, Germany
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Laat MA. Science in brief: Progress in endocrinopathic laminitis research: Have we got a foothold? Equine Vet J 2019; 51:141-142. [DOI: 10.1111/evj.13056] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2018] [Accepted: 11/22/2018] [Indexed: 12/21/2022]
Affiliation(s)
- M. A. Laat
- Science and Engineering Faculty Queensland University of Technology Brisbane Australia
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12
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Patterson-Kane JC, Karikoski NP, McGowan CM. Paradigm shifts in understanding equine laminitis. Vet J 2017; 231:33-40. [PMID: 29429485 DOI: 10.1016/j.tvjl.2017.11.011] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2017] [Revised: 10/08/2017] [Accepted: 11/20/2017] [Indexed: 12/29/2022]
Abstract
Laminitis, one of the most debilitating conditions of all equids, is now known to be the result of several systemic disease entities. This finding, together with other recent developments in the field of laminitis research, have provoked a rethink of our clinical and research strategies for this condition. First, laminitis is now considered to be a clinical syndrome associated with systemic disease (endocrine disease, sepsis or systemic inflammatory response syndrome, SIRS) or altered weight bearing rather than being a discrete disease entity. Next, laminitis associated with endocrine disease (endocrinopathic laminitis) is now believed to be the predominant form in animals presenting (primarily) for lameness. Third, the designation of laminitis as a primary and severe basement membrane pathology now requires revision. Instead, current data now proposes a variable subclinical phase associated with gross changes in the hoof capsule, with stretching and elongation of the lamellar cells an early and key event in the pathophysiology. These findings have fuelled new mechanistic hypotheses and research directions that will be discussed, together with their implications for future clinical management.
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Affiliation(s)
| | - N P Karikoski
- Department of Equine and Small Animal Medicine, Faculty of Veterinary Medicine, University of Helsinki, Viikintie49, FIN-00014 Helsinki, Finland
| | - C M McGowan
- Institutes of Veterinary Science and Ageing and Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool, Leahurst CH64 7TE, UK.
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Bertin FR, Laat MA. The diagnosis of equine insulin dysregulation. Equine Vet J 2017; 49:570-576. [DOI: 10.1111/evj.12703] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2016] [Accepted: 05/16/2017] [Indexed: 12/18/2022]
Affiliation(s)
- F. R. Bertin
- School of Veterinary Science The University of Queensland Gatton Queensland Australia
| | - M. A. Laat
- Science and Engineering Faculty Queensland University of Technology Brisbane Queensland Australia
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14
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Campolo A, de Laat MA, Keith L, Gruntmeir KJ, Lacombe VA. Prolonged hyperinsulinemia affects metabolic signal transduction markers in a tissue specific manner. Domest Anim Endocrinol 2016; 55:41-5. [PMID: 26773366 DOI: 10.1016/j.domaniend.2015.11.001] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/18/2015] [Revised: 11/08/2015] [Accepted: 11/09/2015] [Indexed: 01/27/2023]
Abstract
Insulin dysregulation is common in horses although the mechanisms of metabolic dysfunction are poorly understood. We hypothesized that insulin signaling in striated (cardiac and skeletal) muscle and lamellae may be mediated through different receptors as a result of receptor content, and that transcriptional regulation of downstream signal transduction and glucose transport may also differ between tissues sites during hyperinsulinemia. Archived samples from horses treated with a prolonged insulin infusion or a balanced electrolyte solution were used. All treated horses developed marked hyperinsulinemia and clinical laminitis. Protein expression was compared across tissues for the insulin receptor and insulin-like growth factor 1 receptor (IGF-1R) by immunoblotting. Gene expression of metabolic insulin-signaling markers (insulin receptor substrate 1, Akt2, and glycogen synthase kinase 3 beta [GSK-3β]) and glucose transport (basal glucose transporter 1 and insulin-sensitive glucose transporter 4) was evaluated using real-time reverse transcription polymerase chain reaction. Lamellar tissue contained significantly more IGF-1R protein than skeletal muscle, indicating the potential significance of IGF-1R signaling for this tissue. Gene expression of the selected markers of insulin signaling and glucose transport in skeletal muscle and lamellar tissues was unaffected by prolonged hyperinsulinemia. In contrast, the significant upregulation of Akt2, GSK-3β, GLUT1, and GLUT4 gene expression in cardiac tissue suggested that the prolonged hyperinsulinemia induced an increase in insulin sensitivity and a transcriptional activation of glucose transport. Responses to insulin are tissue-specific, and extrapolation of data across tissue sites is inappropriate.
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Affiliation(s)
- A Campolo
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - M A de Laat
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - L Keith
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - K J Gruntmeir
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - V A Lacombe
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
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Reisinger N, Schaumberger S, Nagl V, Hessenberger S, Schatzmayr G. Concentration Dependent Influence of Lipopolysaccharides on Separation of Hoof Explants and Supernatant Lactic Acid Concentration in an Ex Vivo/In Vitro Laminitis Model. PLoS One 2015; 10:e0143754. [PMID: 26599864 PMCID: PMC4657978 DOI: 10.1371/journal.pone.0143754] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2015] [Accepted: 11/09/2015] [Indexed: 12/30/2022] Open
Abstract
Laminitis is one of the most common diseases in horses. It is not only painful for the animal, but also has a significant financial impact on the equine industry. This multifactorial disease affects the connective tissue of the hoof. However, the pathogenesis of laminitis is still not fully understood. Endotoxins, also known as lipopolysaccharides (LPS), and bacterial exotoxins seem to play an important role during the development of laminitis. The aim of our study was to investigate the effect of increasing LPS concentrations (0, 2.5, 5, 10, and 100 μg/mL) on cell viability of isolated epidermal and dermal hoof cells as well as on the tissue integrity of hoof explants. Furthermore, glucose, acetic acid, lactic acid, and propionic acid concentrations in explant supernatants were measured to evaluate the energy metabolism in the hoof tissue. LPS did not exhibit cytotoxic effects on epidermal or dermal cells. Force required to separate LPS treated hoof explants decreased in a concentration dependent manner. Specifically, explants incubated with 10 and 100 μg/mL needed significantly less force to separate compared to control explants. Lactic acid concentrations were significantly decreased in explants incubated with 5, 10, or 100 μg/mL LPS, while glucose, acetic acid and propionic acid concentrations were unaffected by LPS treatment. Our study indicates that LPS has no cytotoxic effect on epidermal and dermal cells isolated from hoof tissue, but impairs integrity of hoof explants. In addition, LPS led to an alteration of the lactic acid production in the lamellar tissue. Since our data highlight that LPS can affect the integrity of the equine hoof tissue in vitro, endotoxins should be further explored for their contribution to facilitate the development of laminitis.
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Medina-Torres CE, Underwood C, Pollitt CC, Castro-Olivera EM, Hodson MP, Richardson DW, van Eps AW. Microdialysis measurements of lamellar perfusion and energy metabolism during the development of laminitis in the oligofructose model. Equine Vet J 2015; 48:246-52. [DOI: 10.1111/evj.12417] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2014] [Accepted: 01/02/2015] [Indexed: 12/31/2022]
Affiliation(s)
- C. E. Medina-Torres
- Australian Equine Laminitis Research Unit, School of Veterinary Science; The University of Queensland; Gatton Queensland Australia
| | - C. Underwood
- Australian Equine Laminitis Research Unit, School of Veterinary Science; The University of Queensland; Gatton Queensland Australia
| | - C. C. Pollitt
- Australian Equine Laminitis Research Unit, School of Veterinary Science; The University of Queensland; Gatton Queensland Australia
| | - E. M. Castro-Olivera
- Australian Equine Laminitis Research Unit, School of Veterinary Science; The University of Queensland; Gatton Queensland Australia
| | - M. P. Hodson
- Metabolomics Australia - Queensland Node, Australian Institute for Bioengineering and Nanotechnology; The University of Queensland; St Lucia Queensland Australia
| | - D. W. Richardson
- New Bolton Center, Department of Clinical Studies, School of Veterinary Medicine; University of Pennsylvania; Kennett Square Philadelphia USA
| | - A. W. van Eps
- Australian Equine Laminitis Research Unit, School of Veterinary Science; The University of Queensland; Gatton Queensland Australia
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de Laat MA, Clement CK, Sillence MN, McGowan CM, Pollitt CC, Lacombe VA. The impact of prolonged hyperinsulinaemia on glucose transport in equine skeletal muscle and digital lamellae. Equine Vet J 2014; 47:494-501. [DOI: 10.1111/evj.12320] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 06/20/2014] [Indexed: 12/29/2022]
Affiliation(s)
- M. A. de Laat
- Department of Physiological Sciences; Center for Veterinary Health Sciences; Oklahoma State University; Stillwater USA
| | - C. K. Clement
- Department of Physiological Sciences; Center for Veterinary Health Sciences; Oklahoma State University; Stillwater USA
| | - M. N. Sillence
- Earth, Environmental and Biological Sciences; Queensland University of Technology; Brisbane Australia
| | - C. M. McGowan
- Institute of Ageing and Chronic Disease; Faculty of Health and Life Sciences; University of Liverpool; Neston UK
| | - C. C. Pollitt
- Australian Equine Laminitis Research Unit; School of Veterinary Science; The University of Queensland; Gatton Australia
| | - V. A. Lacombe
- Department of Physiological Sciences; Center for Veterinary Health Sciences; Oklahoma State University; Stillwater USA
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de Laat MA, Gruntmeir KJ, Pollitt CC, McGowan CM, Sillence MN, Lacombe VA. Hyperinsulinemia Down-Regulates TLR4 Expression in the Mammalian Heart. Front Endocrinol (Lausanne) 2014; 5:120. [PMID: 25101057 PMCID: PMC4105691 DOI: 10.3389/fendo.2014.00120] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Accepted: 07/08/2014] [Indexed: 01/04/2023] Open
Abstract
Toll-like receptors (TLR) are key regulators of innate immune and inflammatory responses and their activation is linked to impaired glucose metabolism during metabolic disease. Determination of whether TLR4 signaling can be activated in the heart by insulin may shed light on the pathogenesis of diabetic cardiomyopathy, a process that is often complicated by obesity and insulin resistance. The aim of the current study was to determine if supraphysiological insulin concentrations alter the expression of TLR4, markers of TLR4 signaling and glucose transporters (GLUTs) in the heart. Firstly, the effect of insulin on TLR4 protein expression was investigated in vitro in isolated rat cardiac myocytes. Secondly, protein expression of TLR4, the pro-inflammatory cytokines interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) suppressor of cytokine signaling 3 (SOCS3) and GLUTs (1, 4, 8, 12) were examined in the equine ventricular myocardium following a prolonged, euglycemic, hyperinsulinemic clamp. Down-regulation of TLR4 protein content in rat cardiac myocytes was observed after incubation with a supraphysiologic concentration of insulin as well as in the equine myocardium after prolonged insulin infusion. Further, cardiac TLR4 expression was negatively correlated with serum insulin concentration. Markers of cardiac TLR4 signaling and GLUT expression were not affected by hyperinsulinemia and concomitant TLR4 down-regulation. Since TLRs are major determinants of the inflammatory response, our findings suggest that insulin infusion exerts an anti-inflammatory effect in the hearts of non-obese individuals. Understanding the regulation of cardiac TLR4 signaling during metabolic dysfunction will facilitate improved management of cardiac sequela to metabolic syndrome and diabetes.
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Affiliation(s)
- Melody A. de Laat
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA
| | - Kaylynn J. Gruntmeir
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA
| | - Christopher C. Pollitt
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, QLD, Australia
| | - Catherine M. McGowan
- Institute of Ageing and Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool, Neston, UK
| | - Martin N. Sillence
- Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, QLD, Australia
| | - Véronique A. Lacombe
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK, USA
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Burns TA, Watts MR, Weber PS, McCutcheon LJ, Geor RJ, Belknap JK. Effect of dietary nonstructural carbohydrate content on activation of 5'-adenosine monophosphate-activated protein kinase in liver, skeletal muscle, and digital laminae of lean and obese ponies. J Vet Intern Med 2014; 28:1280-8. [PMID: 24750267 PMCID: PMC4857936 DOI: 10.1111/jvim.12356] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2013] [Revised: 12/13/2013] [Accepted: 03/05/2014] [Indexed: 01/16/2023] Open
Abstract
Background In EMS‐associated laminitis, laminar failure may occur in response to energy failure related to insulin resistance (IR) or to the effect of hyperinsulinemia on laminar tissue. 5′‐Adenosine‐monophosphate‐activated protein kinase (AMPK) is a marker of tissue energy deprivation, which may occur in IR. Hypothesis/Objectives To characterize tissue AMPK regulation in ponies subjected to a dietary carbohydrate (CHO) challenge. Animals Twenty‐two mixed‐breed ponies. Methods Immunohistochemistry and immunoblotting for total AMPK and phospho(P)‐AMPK and RT‐qPCR for AMPK‐responsive genes were performed on laminar, liver, and skeletal muscle samples collected after a 7‐day feeding protocol in which ponies stratified on body condition score (BCS; obese or lean) were fed either a low‐CHO diet (ESC + starch, approximately 7% DM; n = 5 obese, 5 lean) or a high‐CHO diet (ESC + starch, approximately 42% DM; n = 6 obese, 6 lean). Results 5′‐Adenosine‐monophosphate‐activated protein kinase was immunolocalized to laminar keratinocytes, dermal constituents, and hepatocytes. A high‐CHO diet resulted in significantly decreased laminar [P‐AMPK] in lean ponies (P = .03), but no changes in skeletal muscle (lean, P = .33; obese, P = .43) or liver (lean, P = .84; obese, P = .13) [P‐AMPK]. An inverse correlation existed between [blood glucose] and laminar [P‐AMPK] in obese ponies on a high‐CHO diet. Conclusions and Clinical Importance Laminar tissue exhibited a normal response to a high‐CHO diet (decreased [P‐AMPK]), whereas this response was not observed in liver and skeletal muscle in both lean (skeletal muscle, P = .33; liver, P = .84) and obese (skeletal muscle, P = .43; liver, P = .13) ponies.
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Affiliation(s)
- T A Burns
- The Ohio State University College of Veterinary Medicine, Columbus, OH
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Expression and regulation of facilitative glucose transporters in equine insulin-sensitive tissue: from physiology to pathology. ISRN VETERINARY SCIENCE 2014; 2014:409547. [PMID: 24977043 PMCID: PMC4060548 DOI: 10.1155/2014/409547] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/10/2013] [Accepted: 12/09/2013] [Indexed: 01/12/2023]
Abstract
Glucose uptake is the rate-limiting step in glucose utilization in mammalians and is tightly regulated by a family of specialized proteins, called the facilitated glucose transporters (GLUTs/SLC2). GLUT4, the major isoform in insulin-responsive tissue, translocates from an intracellular pool to the cell surface and as such determines insulin-stimulated glucose uptake. However, despite intensive research over 50 years, the insulin-dependent and -independent pathways that mediate GLUT4 translocation are not fully elucidated in any species. Insulin resistance (IR) is one of the hallmarks of equine metabolic syndrome and is the most common metabolic predisposition for laminitis in horses. IR is characterized by the impaired ability of insulin to stimulate glucose disposal into insulin-sensitive tissues. Similar to other species, the functional capability of the insulin-responsive GLUTs is impaired in muscle and adipose tissue during IR in horses. However, the molecular mechanisms of altered glucose transport remain elusive in all species, and there is still much to learn about the physiological and pathophysiological functions of the GLUT family members, especially in regard to class III. Since GLUTs are key regulators of whole-body glucose homeostasis, they have received considerable attention as potential therapeutic targets to treat metabolic disorders in human and equine patients.
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de Laat MA, Clement CK, McGowan CM, Sillence MN, Pollitt CC, Lacombe VA. Toll-like receptor and pro-inflammatory cytokine expression during prolonged hyperinsulinaemia in horses: implications for laminitis. Vet Immunol Immunopathol 2013; 157:78-86. [PMID: 24246153 DOI: 10.1016/j.vetimm.2013.10.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2013] [Revised: 10/12/2013] [Accepted: 10/18/2013] [Indexed: 12/31/2022]
Abstract
Equine laminitis, a disease of the lamellar structure of the horse's hoof, can be incited by numerous factors that include inflammatory and metabolic aetiologies. However, the role of inflammation in hyperinsulinaemic laminitis has not been adequately defined. Toll-like receptor (TLR) activation results in up-regulation of inflammatory pathways and the release of pro-inflammatory cytokines, including interleukin-6 (IL-6) and tumour necrosis factor-alpha (TNF-α), and may be a pathogenic factor in laminitis. The aim of this study was to determine whether TLR4 expression and subsequent pro-inflammatory cytokine production is increased in lamellae and skeletal muscle during equine hyperinsulinaemia. Standardbred horses were treated with either a prolonged, euglycaemic hyperinsulinaemic clamp (p-EHC) or a prolonged, glucose infusion (p-GI), which induced marked and moderate hyperinsulinaemia, respectively. Age-matched control horses were treated simultaneously with a balanced electrolyte solution. Treated horses developed clinical (p-EHC) or subclinical (p-GI) laminitis, whereas controls did not. Skeletal muscle and lamellar protein extracts were analysed by Western blotting for TLR4, IL-6, TNF-α and suppressor of cytokine signalling 3 (SOCS3) expression. Lamellar protein expression of TLR4 and TNF-α, but not IL-6, was increased by the p-EHC, compared to control horses. A significant positive correlation was found between lamellar TLR4 and SOCS3. Skeletal muscle protein expression of TLR4 signalling parameters did not differ between control and p-EHC-treated horses. Similarly, the p-GI did not result in up-regulation of lamellar protein expression of any parameter. The results suggest that insulin-sensitive tissues may not accurately reflect lamellar pathology during hyperinsulinaemia. While TLR4 is present in the lamellae, its activation appears unlikely to contribute significantly to the developmental pathogenesis of hyperinsulinaemic laminitis. However, inflammation may have a role to play in the later stages (e.g., repair or remodelling) of the disease.
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Affiliation(s)
- M A de Laat
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - C K Clement
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA
| | - C M McGowan
- Institute of Ageing and Chronic Disease, Faculty of Health and Life Sciences, University of Liverpool, Neston, CH64 7TE, UK
| | - M N Sillence
- Earth, Environmental and Biological Sciences, Queensland University of Technology, Brisbane, Queensland, 4001, Australia
| | - C C Pollitt
- Australian Equine Laminitis Research Unit, School of Veterinary Science, The University of Queensland, Gatton, Queensland, 4343, Australia
| | - V A Lacombe
- Department of Physiological Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74078, USA.
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A potential role for lamellar insulin-like growth factor-1 receptor in the pathogenesis of hyperinsulinaemic laminitis. Vet J 2013; 197:302-6. [DOI: 10.1016/j.tvjl.2012.12.026] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2012] [Revised: 11/29/2012] [Accepted: 12/21/2012] [Indexed: 01/19/2023]
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Rendle DI, Rutledge F, Hughes KJ, Heller J, Durham AE. Effects of metformin hydrochloride on blood glucose and insulin responses to oral dextrose in horses. Equine Vet J 2013; 45:751-4. [PMID: 23600690 DOI: 10.1111/evj.12068] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2012] [Accepted: 01/18/2013] [Indexed: 11/28/2022]
Abstract
REASONS FOR PERFORMING STUDY Metformin is a potential therapeutic agent for the treatment of insulin resistance (IR). In laboratory animals, orally administered metformin reduces intestinal glucose absorption and may therefore affect insulinaemic responses to oral carbohydrate ingestion. OBJECTIVES To determine whether pretreatment with metformin reduces plasma glucose concentration and insulin responses following consumption of dextrose in horses. STUDY DESIGN Therapeutic cross-over study. METHODS Seven healthy Standardbred and Thoroughbred geldings were subjected to an oral dextrose challenge test on 4 occasions: with and without metformin, before and after induction of IR with dexamethasone. Metformin was administered by nasogastric tube at 30 mg/kg bwt 1 h before administration of dextrose. Glucose and insulin concentrations in plasma/serum were measured at regular intervals during each test. Linear mixed models were specified for each predetermined outcome variable, and for each model the 'treatment' was included as a fixed effect with 4 categorical levels (none, metformin, dexamethasone and dexamethasone with metformin) and horse accounted for as a random effect. RESULTS In healthy horses, the administration of metformin resulted in a statistically significant reduction in peak glucose concentration (P = 0.002), area under the glucose curve (P<0.001) and insulin concentration 120 min after dextrose administration (P = 0.011). Following the induction of IR, administration of metformin was associated with significant differences in peak glucose concentration (P<0.001), the percentage increase in glucose concentration (P = 0.010), the area under the glucose curve (P<0.001) and insulin concentration at 120 min (P = 0.034) and 150 min after dextrose administration (P = 0.014). CONCLUSIONS Metformin resulted in reduced glycaemic and insulinaemic responses both in healthy horses and in horses with experimentally induced IR. POTENTIAL RELEVANCE Metformin may benefit horses with naturally acquired IR by reducing glycaemic and insulinaemic responses to dietary nonstructural carbohydrates. Further investigations into the mechanisms of action of metformin in horses and controlled clinical trials are warranted.
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Affiliation(s)
- D I Rendle
- The Liphook Equine Hospital, Liphook, UK
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Katz LM, Bailey SR. A review of recent advances and current hypotheses on the pathogenesis of acute laminitis. Equine Vet J 2013; 44:752-61. [PMID: 23106629 DOI: 10.1111/j.2042-3306.2012.00664.x] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
With the increasing number of studies being published on the different experimental models used to induce and study acute laminitis, the pathophysiological events associated with these various models (i.e. starch overload, oligofructose overload, black walnut extract and hyperinsulinaemia) can be compared more realistically. Within this review, the mechanisms for metabolic vs. inflammatory laminitis are discussed, and the question of how pasture laminitis may fit into any of the proposed mechanisms is addressed.
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Affiliation(s)
- L M Katz
- School of Veterinary Medicine, University College Dublin, Dublin, Ireland.
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Gauff F, Patan-Zugaj B, Licka TF. Hyperinsulinaemia increases vascular resistance and endothelin-1 expression in the equine digit. Equine Vet J 2013; 45:613-8. [PMID: 23489109 DOI: 10.1111/evj.12040] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Accepted: 12/05/2012] [Indexed: 11/29/2022]
Abstract
REASONS FOR PERFORMING STUDY Insulin leads to overexpression of endothelin-1 (ET-1) in the endothelium of insulin-resistant rodents. If this is also the case in equine laminar tissue, this could explain the predisposition of insulin-resistant horses to laminitis. OBJECTIVES To investigate the effect of hyperinsulinaemia on metabolism and vascular resistance of the isolated equine digit in a model of extracorporeal perfusion. STUDY DESIGN Randomised, controlled study with interventional group, with blinded evaluation of histology results. METHOD After exsanguination, equine digits (n = 11) and autologous blood were collected at an abattoir. One digit served as a hyperinsulinaemic pilot limb, 5 digits were assigned to the hyperinsulinaemic perfusion (IP) group and 5 to the control perfusion (CP) group. Digits were perfused for 10 h at a defined perfusion rate of 12 ml/min/kg. After the first hour of perfusion (equilibration period), insulin was added to the reservoir of the IP digits. Perfusion pressure, glucose consumption, lactate and lactate dehydrogenase were monitored. Vascular resistance was calculated as perfusion pressure (in millimetres of mercury) in relation to the flow rate (in millilitres per minute). After perfusion, histology samples of the dorsal hoof wall (haematoxylin & eosin or periodic acid-Schiff) were evaluated. Immunohistology with a polyclonal rabbit-derived anti-endothelin antibody was used for detection of ET-1. RESULTS In the IP group, the mean insulin concentration in the plasma of the perfusate was 142 ± 81 μiu/ml, while insulin concentration was <3 μiu/ml in the CP group. Mean vascular resistance was significantly higher (P<0.01) in the IP group (2.04 ± 1.13 mmHg/ml/min) than in the CP group (1.31 ± 0.55 mmHg/ml/min). Histology of the IP group samples showed significantly more vessels with an open lumen, increased width of the secondary epidermal lamellae and formation of oedema. In the lamellar vessels (veins and arteries) and nerve fibres, ET-1 expression was much more prominent in the IP group than in the CP group samples. CONCLUSIONS Short-term hyperinsulinaemia leads to increased vascular resistance in the equine digit and increased expression of ET-1 in the laminar tissue.
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Affiliation(s)
- F Gauff
- Clinic of Orthopaedics in Large Animals, Department of Horses and Small Animals, Vienna University of Veterinary Medicine, Austria.
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Patan-Zugaj B, Gauff FC, Licka TF. Effects of the addition of endotoxin during perfusion of isolated forelimbs of equine cadavers. Am J Vet Res 2013; 73:1462-8. [PMID: 22924729 DOI: 10.2460/ajvr.73.9.1462] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To examine the effect of endotoxins on metabolism and histopathologic changes of isolated perfused equine forelimbs. SAMPLE Forelimbs (comprising the metacarpus and digit) were collected from cadavers of 12 healthy adult horses after slaughter at an abattoir (14 limbs; 1 forelimb of 10 horses and both forelimbs of 2 horses). PROCEDURES Forelimbs were perfused for 10 hours with autologous blood, with and without the addition of endotoxin (80 ng of lipopolysaccharide [LPS]/L). Two limbs of the endotoxin exposure group and 2 nonperfused limbs were loaded to failure of the suspensory apparatus of the pedal bone to evaluate the effect of body weight. Metabolic and histologic variables were evaluated. RESULTS Blood pressure increased during the first hour and did not differ between groups. Lactate dehydrogenase activity was similar in both groups and increased significantly during the 10-hour period; glucose consumption at 5 hours and lactate concentration at 8 hours were significantly higher in limbs exposed to endotoxin. The width of secondary epidermal lamellae was greater in LPS limbs. In the primary dermal lamellae of LPS limbs, there were significantly more vessels with an open lumen and aggregates of intravascular neutrophils. CONCLUSIONS AND CLINICAL RELEVANCE In the blood-perfused isolated forelimbs of equine cadavers, exposure to LPS led to significant changes in the laminar tissue as well as to metabolic changes. Therefore, endotoxin should be considered as a causative factor for laminitis and not merely as a risk factor.
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Affiliation(s)
- Bianca Patan-Zugaj
- Department for Horses and Small Animals, Veterinary University Vienna, A-1210 Vienna, Austria
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Affiliation(s)
- N. Menzies-Gow
- Department of Veterinary Clinical Science; Royal Veterinary College; North Mymms; UK
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de Laat MA, Kyaw-Tanner MT, Sillence MN, McGowan CM, Pollitt CC. Advanced glycation endproducts in horses with insulin-induced laminitis. Vet Immunol Immunopathol 2011; 145:395-401. [PMID: 22240145 DOI: 10.1016/j.vetimm.2011.12.016] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2011] [Revised: 12/19/2011] [Accepted: 12/20/2011] [Indexed: 01/07/2023]
Abstract
Advanced glycation endproducts (AGEs) have been implicated in the pathogenesis of cancer, inflammatory conditions and diabetic complications. An interaction of AGEs with their receptor (RAGE) results in increased release of pro-inflammatory cytokines and reactive oxygen species (ROS), causing damage to susceptible tissues. Laminitis, a debilitating foot condition of horses, occurs in association with endocrine dysfunction and the potential involvement of AGE and RAGE in the pathogenesis of the disease has not been previously investigated. Glucose transport in lamellar tissue is thought to be largely insulin-independent (GLUT-1), which may make the lamellae susceptible to protein glycosylation and oxidative stress during periods of increased glucose metabolism. Archived lamellar tissue from horses with insulin-induced laminitis (n=4), normal control horses (n=4) and horses in the developmental stages (6h, 12h and 24h) of the disease (n=12) was assessed for AGE accumulation and the presence of oxidative protein damage and cellular lipid peroxidation. The equine-specific RAGE gene was identified in lamellar tissue, sequenced and is now available on GenBank. Lamellar glucose transporter (GLUT-1 and GLUT-4) gene expression was assessed quantitatively with qRT-PCR in laminitic and control horses and horses in the mid-developmental time-point (24 h) of the disease. Significant AGE accumulation had occurred by the onset of insulin-induced laminitis (48 h) but not at earlier time-points, or in control horses. Evidence of oxidative stress was not found in any group. The equine-specific RAGE gene was not expressed differently in treated and control animals, nor was the insulin-dependent glucose transporter GLUT-4. However, the glucose transporter GLUT-1 was increased in lamellar tissue in the developmental stages of insulin-induced laminitis compared to control horses and the insulin-independent nature of the lamellae may facilitate AGE formation. However, due to the lack of AGE accumulation during disease development and a failure to detect an increase in ROS or upregulation of RAGE, it appears unlikely that oxidative stress and protein glycosylation play a central role in the pathogenesis of acute, insulin-induced laminitis.
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Affiliation(s)
- M A de Laat
- Australian Equine Laminitis Research Unit, School of Veterinary Science, Faculty of Science, The University of Queensland, Gatton, Queensland 4343, Australia.
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