Insulin is a hormone produced by the pancreas that plays a pivotal role in regulating glucose metabolism in horses. It facilitates the uptake of glucose by cells, thus maintaining blood sugar levels within a normal range. Insulin's function is integral to energy balance and metabolic processes in equines. Disruptions in insulin regulation can lead to metabolic disorders such as Equine Metabolic Syndrome (EMS), characterized by insulin resistance and associated with obesity and laminitis. This page aggregates peer-reviewed research studies and scholarly articles that explore the physiological role, regulatory mechanisms, and clinical implications of insulin in equine health and disease management.
Rapson JL, Schott HC, Nielsen BD, McCutcheon LJ, Harris PA, Geor RJ.Age and diet may affect insulin sensitivity (SI) but these factors have received limited investigation in horses. Objective: To measure minimal model parameters during an insulin-modified frequently sampled intravenous glucose tolerance test (FSIGTT) after adaptation to a forage only diet (HAY) or forage supplemented with either starch/sugar-rich (SS) or oil/fibre-rich (FF) concentrate feeds; and to assess glucose and insulin responses to a standardised meal challenge (SMC, 4 g/kg BW of SS) after diet adaptation in adult and aged mares. Methods: Latin square design with eight adult (5-12 yea...
Marycz K, Michalak I, Kornicka K.Horses metabolic disorders have become an important problem of modern veterinary medicine. Pathological obesity, insulin resistance and predisposition toward laminitis are associated with Equine Metabolic Syndrome (EMS). Based on pathogenesis of EMS, dietary and cell therapy management may significantly reduce development of this disorder. Special attention has been paid to the diet supplementation with highly bioavailable minerals and mesenchymal stem cells (MSC) which increase insulin sensitivity. In nutrition, there is a great interests in natural algae enriched via biosorption process with...
Szydlarska J, Weiss C, Marycz K.Methyl-β-cyclodextrin (MβCD) is a cyclic oligosaccharide, commonly used as a pharmacological agent to deplete membrane cholesterol. In this study, we examined the effect of MβCD on adipose-derived mesenchymal stromal cells (ASCs) isolated form healthy horses (ASC) and from horses suffering from metabolic syndrome (ASC). We investigated the changes in the mRNA levels of the glucose transporter 4 (GLUT4) and found that MβCD application may lead to a significant improvement in glucose transport in ASC. We also showed that MβCD treatment affected GLUT4 upregulation in an insulin-independent m...
Kheder MH, Bailey SR, Dudley KJ, Sillence MN, de Laat MA.Equine metabolic syndrome (EMS) is associated with insulin dysregulation, which often manifests as post-prandial hyperinsulinemia. Circulating concentrations of the incretin hormone, glucagon-like peptide-1 (GLP-1) correlate with an increased insulin response to carbohydrate intake in animals with EMS. However, little is known about the equine GLP-1 receptor (eGLP-1R), or whether GLP-1 concentrations can be manipulated. The objectives were to determine (1) the tissue localisation of the eGLP-1R, (2) the GLP-1 secretory capacity of equine intestine in response to glucose and (3) whether GLP-1 s...
Robles M, Nouveau E, Gautier C, Mendoza L, Dubois C, Dahirel M, Lagofun B, Aubrière MC, Lejeune JP, Caudron I, Guenon I, Viguié C, Wimel L....Obesity is a growing concern in horses. The effects of maternal obesity on maternal metabolism and low-grade inflammation during pregnancy, as well as offspring growth, metabolism, low-grade inflammation, testicular maturation and osteochondrotic lesions until 18 months of age were investigated. Twenty-four mares were used and separated into two groups at insemination according to body condition score (BCS): Normal (N, n = 10, BCS ≤4) and Obese (O, n = 14, BCS ≥4.25). BCS and plasma glucose, insulin, triglyceride, urea, non-esterified fatty acid, serum amyloid A (SAA), leptin and adiponect...
Hofberger SC, Gauff F, Thaller D, Morgan R, Keen JA, Licka TF.OBJECTIVE To identify signs of tissue-specific cortisol activity in samples of suspensory ligament (SL) and neck skin tissue from horses with and without pituitary pars intermedia dysfunction (PPID). SAMPLE Suspensory ligament and neck skin tissue samples obtained from 26 euthanized horses with and without PPID. PROCEDURES Tissue samples were collected from 12 horses with and 14 horses without PPID (controls). Two control horses had received treatment with dexamethasone; data from those horses were not used in statistical analyses. The other 12 control horses were classified as old horses (≥...
Newkirk KM, Ehrensing G, Odoi A, Boston RC, Frank N.OBJECTIVE To assess insulin, glucagon, and somatostatin expression within pancreatic islets of horses with and without insulin resistance. ANIMALS 10 insulin-resistant horses and 13 insulin-sensitive horses. PROCEDURES For each horse, food was withheld for at least 10 hours before a blood sample was collected for determination of serum insulin concentration. Horses with a serum insulin concentration 20 μU/mL underwent a frequently sampled IV glucose tolerance test to determine sensitivity to insulin by minimal model analysis. Horses with a sensitivity to insulin < 1.0 × 10 L•min•mU w...
Warnken T, Delarocque J, Schumacher S, Huber K, Feige K.Insulin dysregulation (ID) with basal or postprandial hyperinsulinemia is one of the key findings in horses and ponies suffering from the equine metabolic syndrome (EMS). Assessment of ID can easily be performed in clinical settings by the use of oral glucose challenge tests. Oral glucose test (OGT) performed with 1 g/kg bodyweight (BW) glucose administered via naso-gastric tube allows the exact administration of a defined glucose dosage in a short time. However, reliable cut-off values have not been available so far. Therefore, the aim of the study was to describe variations in insulin respo...
Marycz K, Kornicka K, Szlapka-Kosarzewska J, Weiss C.Nowadays, endocrine disorders have become more frequent in both human and veterinary medicine. In horses, reduced physical activity combined with carbohydrate and sugar overload may result in the development of the so-called equine metabolic syndrome (EMS). EMS is characterized by insulin resistance, hyperinsulinemia, elevated blood triglyceride concentrations and usually obesity. Although the phenotypic features of EMS individuals are well known, the molecular mechanism underlying disease development remains elusive. Therefore, in the present study, we analyzed insulin-sensitive tissues, i.e....
Auyyuenyong R, Henze A, Ungru J, Schweigert FJ, Raila J, Vervuert I.Obesity is a key component of equine metabolic syndrome, which is highly associated with laminitis. Feed restriction and/or exercise are known to alleviate the detrimental effects of insulin resistance in obese ponies. However, little is known about changes in the serum lipid patterns due to weight reduction and its association with disease outcomes. Therefore, the lipid patterns in the serum of 14 mature ponies before and after a 14-week body weight reduction program (BWRP) were investigated by multi-one-dimensional thin-layer chromatography (MOD-TLC). Additionally, sensitivity to insulin (SI...
Meier AD, de Laat MA, Reiche DB, Pollitt CC, Walsh DM, McGree JM, Sillence MN.The aim of this study was to investigate the relationship between laminitis development in ponies and insulin/glucose concentrations in response to the oral glucose test (OGT) and a dietary challenge high in nonstructural carbohydrates (NSCs). After undergoing an OGT (1 g dextrose/kg BW in feed), 37 ponies with 2-h serum insulin concentrations ranging from 22 to 1,133 μIU/mL were subjected to a diet challenge period (DCP), consuming 12 g NSC/kg BW/d for up to 18 d. Insulin and glucose responses were measured on day 2 of the DCP. Clinical laminitis was diagnosed by blinded experts and confi...
Jacob SI, Geor RJ, Weber PSD, Harris PA, McCue ME.Diagnosis of equine pituitary pars intermedia dysfunction (PPID) remains a challenge as multiple factors (stress, exercise, and time of year) influence ACTH and cortisol concentrations. To assess endocrine status in a study designed to evaluate the effects of age and diet on glucose and insulin dynamics, we performed thyrotropin-releasing hormone (TRH) stimulation tests and overnight dexamethasone suppression tests in March, May, August, and October on 16 healthy Thoroughbred and Standardbred mares and geldings. Horses were grouped by age: adult (mean ± SD; 8.8 ± 2.9 yr; n = 8) and aged (20...
Cantarelli C, Dau SL, Stefanello S, Azevedo MS, De Bastiani GR, Palma HE, Brass KE, De La Côrte FD.Owing to the high prevalence of obesity in Crioulo horses, information allowing early diagnosis of equine metabolic syndrome (EMS) and prevention of the associated laminitis is of great value. The aim of this study was to evaluate the occurrence of EMS and the response to an oral sugar test (OST) in obese Crioulo horses. Twenty-two Crioulo horses were allocated into 3 groups according to their body condition score (BCS out of 9) and presence or absence of laminitis as follows: CON (6/22), BCS < 7; OB (8/22), BCS ≥ 7; and LAM (8/22), BCS ≥7 with clinical and/or radiographic signs of lam...
Jacob SI, Geor RJ, Weber PSD, Harris PA, McCue ME.Glucose and insulin dynamics may be different in adult and aged horses. Objective: To determine the effects of age and dietary carbohydrates on glucose and insulin dynamics in healthy horses. Methods: Balanced Latin square with four isocaloric diets: CONTROL (hay plus restricted-starch-and-sugar fortified pellets), STARCH (control plus kibbled corn), FIBER (control plus unmolassed sugar beet pulp/soybean hull pellets) and SUGAR (control plus dextrose powder). Methods: A total of 16 healthy Thoroughbreds and Standardbreds divided into two age groups: ADULT (8.8 ± 2.9 years; n = 8) and AGE...
Tóth B, Auth A, Rompos L, Bakos Z.Gastrointestinal and other systemic diseases of Equidae are often characterised by partial or complete inappetence. The catabolic processes may lead to lipid mobilisation and other metabolic disturbances. Evidence from earlier studies has revealed that during feed deprivation/inappetence, the conjugation of bilirubin is reduced causing a substantial rise of the total bilirubin and its unconjugated fraction. Objective: We hypothesised that during feed deprivation, the serum concentration of free fatty acids (FFA), triglycerides (TG), blood urea nitrogen (BUN), total bilirubin (tBIL), total bile...
Lindåse S, Nostell K, Söder J, Bröjer J.A hyperbolic relationship between β-cell response and insulin sensitivity (IS) has been described in several species including rodents, dogs, and humans. This relationship has not been elucidated in the horse. Objective: To determine whether the hyperbolic relationship between β-cell response and IS exists in horses by using indices of β-cell response from the oral sugar test (OST) and IS measurements from the euglycemic hyperinsulinemic clamp (EHC). A second aim was to compare how well IS estimates from the OST and EHC correlate. Methods: Forty-nine horses with different degrees of insulin...
Nawrocka D, Kornicka K, Śmieszek A, Marycz K.Equine Metabolic Syndrome (EMS) is a steadily growing life-threatening endocrine disorder linked to insulin resistance, oxidative stress, and systemic inflammation. Inflammatory microenvironment of adipose tissue constitutes the direct tissue milieu for various cell populations, including adipose-derived mesenchymal stromal cells (ASCs), widely considered as a potential therapeutic cell source in the course of the treatment of metabolic disorders. Moreover, elevated oxidative stress induces inflammation in intestinal epithelial cells (IECs)-the first-line cells exposed to dietary compounds. In...
Kheder MH, Sillence MN, Bryant LM, de Laat MA.Metabolic disease is a significant problem that causes a range of species-specific comorbidities. Recently, a better understanding of glucose-dependent insulinotropic polypeptide (GIP) biology has led to the suggestion that inhibiting its action may attenuate obesity in several species. In horses, antagonism of GIP may also reduce hyperinsulinemia, which leads to insulin-associated laminitis, a painful comorbidity unique to this species. However, little is known about GIP in horses. The aims of this study were to examine the tissue distribution of equine GIP receptors (eGIPR), to determine whe...
Brinkmann L, Riek A, Gerken M.Domesticated horses are increasingly kept under semi-natural housing conditions, whereas their adaptation capacity is not fully investigated. In all, 10 Shetland pony mares were held under semi-extensive conditions for 1 year. In winter animals were allocated into two feeding groups (60% and 100% of maintenance energy requirement, respectively). Triiodothyronine, thyroxine, non-esterified fatty acids (NEFA), total bilirubin, total protein, triglyceride, glucose, insulin and hair length were measured at monthly intervals, whereas BW, body condition score, cresty neck score and resting heart rat...
Beythien E, Wulf M, Ille N, Aurich J, Aurich C.In pregnant mares, peripheral insulin antagonism channels glucose preferentially to the foetus. On the other hand, horses reduce their metabolic activity in winter. Taking these aspects of equine pregnancy and metabolism together, we hypothesized that glucose clearance from blood and the insulin response to glucose do not only change throughout gestation but also with season. To test this hypothesis, the glucose and insulin response to an oral glucose test and relative insulin release were analysed in pregnant mares (n=12) and in geldings (n=10) as controls. Animals were tested in June, Septem...
Bonelli F, Sgorbini M, Meucci V, Sighieri C, Baragli P.Low intensity exercise increases insulin-stimulated glucose uptake in skeletal muscle and decreases its plasma concentration. In this study, plasma insulin and glucose concentrations were evaluated 5min before and 5, 15, 25, 35, 45 and 60min after an IV bolus of glucose in 12 Thoroughbreds before and after 1 month of submaximal aquatraining exercise, monitored using heart rate and blood lactate. Plasma glucose concentrations were evaluated using a colorimetric enzymatic method, and plasma insulin concentrations with a solid-phase radioimmunoassay method. Pre-training plasma glucose concentrati...
Bertin FR, de Laat MA.Insulin dysregulation is the hallmark of equine metabolic syndrome and has received attention because of its direct association with laminitis. In the absence of an adequate treatment for laminitis, a focus on prophylaxis is needed, making early detection of individuals at risk of developing laminitis one of the main challenges in equine endocrinology. Recent studies have shown that insulin dysregulation goes beyond tissue insulin resistance and it is now demonstrated that the equine enteroinsular axis plays a major role in insulin secretion and equine hyperinsulinaemia. In this review, we dis...
Bochnia M, Schürer C, Gottschalk J, Einspanier A, Hillegeist D, Wensch-Dorendorf M, Greef JM, Glatter M, Zeyner A.Aim of this study was to compare glycemic and insulinemic responses and feed intake patterns in sport ponies after feeding isoenergetic quantities of low-starch muesli feed high in fat and fibre (FF) or oat grains (OG). Six sport ponies were randomly assigned to one of these two treatment groups for 2 × 3 weeks according to a crossover-design. Ponies received two equal meals/day of either semi-crushed OG (1 g starch/kg bwt*meal ) or an isoenergetic quantity of FF. Hay was also given in two equal meals/day and provided the remaining metabolisable energy up to 1.3-fold maintenance level. On...
Glatter M, Bochnia M, Goetz F, Gottschalk J, Koeller G, Mielenz N, Hillegeist D, Greef JM, Einspanier A, Zeyner A.This study aimed to investigate the impact of the supplementation of a pre-biotic compound [Jerusalem artichoke meal (JAM)] on the glycaemic and insulinaemic response in healthy, non-obese warm-blooded horses. Six adult mares [mean body weight (bwt) 529 ± 38.7 kg; body condition score 5.1 ± 0.49/9] were used. In two equal meals per day, the horses received crushed oat grains (1 g starch/kg bwt per day) and meadow hay (2 kg/100 kg bwt per day) which together were likely to meet the energy recommendation for light work (GfE, ). Additionally, they received either 0.15 g fructo-oligosac...
Frank N, Walsh DM.Repeatability of the oral sugar test (OST) has not been evaluated. Objective: We hypothesized that OST glucose, insulin, active (aGLP-1) and total (tGLP-1) glucagon-like peptide 1, and high-molecular-weight (HMW) adiponectin results would be repeatable. Methods: Fifty-three horses from a Tennessee research facility (n = 23) and private practice in Missouri (n = 30), including animals with medical histories of equine metabolic syndrome. Methods: Two OSTs were performed 7-14 days apart and plasma glucose and insulin concentrations were measured at 0, 60, and 75 minutes; a positive result w...
Frank N, Hermida P, Sanchez-Londoño A, Singh R, Gradil CM, Uricchio CK.Octreotide is a somatostatin analog that suppresses insulin secretion. Objective: We hypothesized that octreotide would suppress insulin concentrations in horses and that normal (N) horses and those with insulin dysregulation (ID) would differ significantly in their plasma glucose and insulin responses to administration of octreotide. Methods: Twelve horses, N = 5, ID = 7. Methods: Prospective study. An oral sugar test was performed to assign horses to N and ID groups. Octreotide (1.0 μg/kg IV) was then administered, and blood was collected at 0, 5, 10, 15, 20, 25, 30, 45, 60, 75, and 90 minu...
Warnken T, Brehm R, Feige K, Huber K.The aim of the study was to analyze key proteins of the equine insulin signaling cascade and their extent of phosphorylation in biopsies from muscle tissue (MT), liver tissue (LT), and nuchal AT, subcutaneous AT, and retroperitoneal adipose tissues. This was investigated under unstimulated (B1) and intravenously insulin stimulated (B2) conditions, which were achieved by injection of insulin (0.1 IU/kg bodyweight) and glucose (150 mg/kg bodyweight). Twelve warmblood horses aged 15 ± 6.8 yr (yr), weighing 559 ± 79 kg, and with a mean body condition score of 4.7 ± 1.5 were included in the s...
Ropka-Molik K, Stefaniuk-Szmukier M, Z Ukowski K, Piórkowska K, Bugno-Poniewierska M.It has been found that Arabian and Thoroughbred horses differ in muscle fiber structure and thus in physiological changes occurring in muscles during exercise. The aim of the present study was to identify the global gene expression modifications that occur in skeletal muscle following a training regime to prepare for flat racing. Whole transcriptomes of muscle (gluteus medius) were compared between three time points of tissue collection: T (untrained horses), T (horses after intense gallop phase), and T (horses at the end of racing season), 23 samples in total. The numerous groups of exercise-...
Aguiar FLN, Gastal GDA, Ishak GM, Gastal MO, Teixeira DIA, Feugang JM, Figueiredo JR, Gastal EL.The effect of FSH supplementation on an enriched cultured medium containing insulin (10 ng/mL) and EGF (50 ng/mL) was investigated on in vitro culture of equine ovarian biopsy tissue. Ovarian tissue fragments were collected from mares (n = 10) and distributed in the following treatments: noncultured control, cultured control, and cultured + FSH. Both treated groups were cultured for 7 or 15 days. The end points evaluated were: follicular morphology, estradiol levels in the culture medium, fluorescence intensity for TUNEL, EGFR and Ki-67 detection, and gene expression of GDF-9, BMP-15, a...
Heliczer N, Gerber V, Bruckmaier R, van der Kolk JH, de Solis CN.OBJECTIVE To determine whether hypertension, high sympathetic tone, resting and exercising arrhythmias, and echocardiographic changes consistent with hypertensive cardiomyopathy were associated with equine metabolic syndrome (EMS) in ponies. DESIGN Prospective case-control study. ANIMALS 19 privately owned ponies with a diagnosis of EMS (history of laminitis, body condition score ≥ 7/9, cresty neck score ≥ 3/5, and abnormal oral sugar test result; cases) and 20 healthy control ponies. PROCEDURES Heart rate (HR), noninvasively measured arterial blood pressure (BP), markers of autonomic tone...
Loos CMM, Urschel KL, Vanzant ES, Oberhaus EL, Bohannan AD, Klotz JL, McLeod KR.The objectives of the study were to study the effects of the synthetic ergot alkaloid (EA), bromocriptine, on glucose and lipid metabolism in insulin dysregulated (ID, n = 7) and non-ID (n = 8) mares. Horses were individually housed and fed timothy grass hay and two daily concentrate meals so that the total diet provided 120% of daily DE requirements for maintenance. All horses were given intramuscular bromocriptine injections (0.1 mg/kg BW) every 3 days for 14 days. Before and after 14 days of treatment horses underwent a combined glucose-insulin tolerance test (CGIT) to assess insulin sensit...
DeBoer ML, Hathaway MR, Kuhle KJ, Weber PSD, Reiter AS, Sheaffer CC, Wells MS, Martinson KL.Elevated nonstructural carbohydrate (NSC) values in pasture forages can cause adverse health effects in some horses (Equus caballus L.). The objectives of this study were to determine the impact of different forage species on blood glucose and insulin concentrations of horses throughout the grazing season. Research was conducted in July (summer) and September (fall) in St. Paul, MN. Alfalfa (Medicago sativa L.), mixed perennial cool-season grasses (CSG), and teff (Eragrostis tef [Zucc.] Trotter) pastures were grazed by six horses (24 ± 2 years) that were randomly assigned to one of three for...
Urschel KL, Geor RJ, Waterfall HL, Shoveller AK, McCutcheon LJ.Providing protein or amino acid mixtures in combination with glucose to post exercise in man has resulted in increases in the post feeding insulin response and in muscle glycogen and protein synthesis rates. However, whether protein and/or amino acids can modify the post exercise insulin responses in horses remains to be fully elucidated. Objective: To determine whether whey protein or leucine addition to a glucose solution affects the post gavage plasma insulin, glucose and amino acid responses in horses and whether these responses are different following a period of exercise vs. rest. Method...
Kaske M, Elmahdi B, von Engelhardt W, Sallmann HP.It had been suggested that marked species differences in glucose tolerance tests were due to differences in insulin resistance. To compare insulin responsiveness, euglycemic hyperinsulinemic clamps were carried out in sheep, ponies, miniature pigs and camels. Porcine insulin was infused as primed-continuous infusions for 2 h (6 mU x kg(-1) x min(-1)). The steady state glucose infusion rates in the pigs, sheep, ponies and camels were 96.0, 18.6, 7.1 and 6.1 micromol x kg(-1) x min(-1), respectively. The maximal plasma insulin concentrations during the insulin infusions were 2,700 microU x ml(-1...
Peugnet P, Robles M, Mendoza L, Wimel L, Dubois C, Dahirel M, Guillaume D, Camous S, Berthelot V, Toquet MP, Richard E, Sandersen C, Chaffaux S....In stud management, broodmares are commonly fed concentrates in late pregnancy. This practice, however, was shown to correlate with an increased incidence of osteochondrosis in foals, which may be related to insulin sensitivity. We hypothesized that supplementation of the mare with barley in the last trimester of pregnancy alters the pre-weaning foal growth, glucose metabolism and osteoarticular status. Here, pregnant multiparous saddlebred mares were fed forage only (group F, n=13) or both forage and cracked barley (group B, n=12) from the 7th month of pregnancy until term, as calculated to c...
Keen JA, McGorum BC, Hillier C, Nally JE.This study investigated the effects of cortisol and insulin, hormones that affect both glycaemic status and vascular function, on the in vitro contractility of isolated healthy equine small laminar veins. Small veins (150-500 μm) draining the digital laminae from healthy horses or ponies were investigated by wire myography. Concentration response curves were constructed for noradrenaline (NA), phenylephrine (PE), endothelin-1 (ET-1) and 5-hydroxytryptamine (5-HT) in the presence of either cortisol (10(-6 ) m) or insulin (1000 μIU/mL). Cortisol significantly increased the maximum contractilit...
Shepherd ML, Pleasant RS, Crisman MV, Werre SR, Milton SC, Swecker WS.The objective of this study was to determine the effects of high and moderate non-structural carbohydrates (NSC) hay on insulin, glucose, triglyceride, and leptin concentrations in overweight Arabian geldings. Eight adult overweight (average BCS 7 [9-point scale]) Arabian geldings were fed each of two orchardgrass hays, high NSC (18% DM) and moderate NSC (12% DM), in a cross over design during two 28-day periods. Body weight and body condition score assessment along with blood sampling to measure insulin, glucose, leptin, and triglyceride concentrations were performed on days 0, 7, 14, 21 and ...
Beckelmann J, Budik S, Helmreich M, Palm F, Walter I, Aurich C.An adjustment of sex ratio of offspring to the conditions present at conception is seen in many mammals including horses. This depends on preferential survival of male embryos under conditions of high energy intake. In several species, growth factors including insulin like growth factor (IGF)-1 have been shown to promote embryonic development by decreasing apoptosis and increasing cell proliferation. We hypothesized that sex-related differences in IGF-1 expression in equine embryos during the phase of maternal recognition of pregnancy might exist and thus contribute to preferential survival of...
Bourebaba L, Serwotka-Suszczak A, Pielok A, Sikora M, Mularczyk M, Marycz K.Equine metabolic syndrome (EMS) is a multifactorial pathology gathering insulin resistance, low-grade inflammation and past or chronic laminitis. Among the several molecular mechanisms underlying EMS pathogenesis, increased negative insulin signalling regulation mediated by protein tyrosine phosphatase 1 B (PTP1B) has emerged as a critical axis in the development of liver insulin resistance and general metabolic distress associated to increased ER stress, inflammation and disrupted autophagy. Thus, the use of PTP1B selective inhibitors such as MSI-1436 might be considered as a golden therapeut...
Johnson PJ, Wiedmeyer CE, LaCarrubba A, Messer NT, Dingfelder HA, Cogswell AM, Amorim JR, Ganjam VK.The combined glucose-insulin test (CGIT) is helpful for evaluating insulin sensitivity. A continuous glucose monitoring system (CGMS) reports changes in interstitial glucose concentrations as they occur in the blood. Use of the CGMS minimizes animal contact and may be useful when performing a CGIT. Objective: Results obtained using a CGMS are useful for the evaluation of glucose responses during the evaluation of insulin sensitivity in equids. Methods: Seven mature, obese ponies. Methods: Ponies were equipped with CGMS for determination of interstitial glucose concentrations. Glucose (150 mg/k...
Kullmann A, Weber PS, Bishop JB, Roux TM, Norby B, Burns TA, McCutcheon LJ, Belknap JK, Geor RJ.Hyperinsulinaemia is implicated in the pathogenesis of endocrinopathic laminitis. Insulin can bind to different receptors: two insulin receptor isoforms (InsR-A and InsR-B), insulin-like growth factor-1 receptor (IGF-1R) and InsR/IGF-1R hybrid receptor (Hybrid). Currently, mRNA expression of these receptors in equine tissues and the influence of body type and dietary carbohydrate intake on expression of these receptors is not known. Objective: The study objectives were to characterise InsR-A, InsR-B, IGF-1R and Hybrid expression in lamellar tissue (LT) and insulin responsive tissues from horse...
Rossdale PD, Ousey JC, Silver M, Fowden A.This paper describes criteria used to assess maturity of the newborn foal and their clinical application to field cases of prematurity and dysmaturity. Premature and mature foals may be clearly distinguished by their behavioural and physical characteristics. Measurement of haematological parameters (mean cell volume, total white cell and differential counts), pancreatic beta cell activity (plasma glucose and insulin levels), adrenocortical-medullary function (plasma cortisol, adrenocorticotrophic hormone and catecholamines) and the renin-angiotensin system (plasma renin substrate concentration...
Urschel KL, Escobar J, McCutcheon LJ, Geor RJ.Little is known about the role insulin plays in regulating whole-body and muscle protein metabolism in horses. The objective of this study was to determine the effects of graded rates of insulin infusion on plasma amino acid concentrations and the activation of factors in the mechanistic target of rapamycin signaling pathway in the skeletal muscle of horses. Isoglycemic, hyperinsulinemic clamp procedures were conducted in 8 mature, thoroughbred mares receiving 4 rates of insulin infusion: 0 mU · kg(-1) · min(-1) (CON), 1.2 mU · kg(-1) · min(-1) (LOWINS), 3 mU · kg(-1) · min(-1) (MEDINS),...
Robles M, Peugnet P, Dubois C, Piumi F, Jouneau L, Bouchez O, Aubrière MC, Dahirel M, Aioun J, Wimel L, Couturier-Tarrade A, Chavatte-Palmer P.Feeding pregnant broodmares with cereal concentrates has been shown to increase maternal insulin resistance and affect foal metabolism in the short and long-term. These effects are likely to be mediated by the placenta. Here, we investigated feto-placental biometry and placental structure and function at term in mares fed with or without cereals concentrates. From 7 months of gestation, 22 multiparous mares were fed forage only (group F (n = 12)) or received forage and cracked barley (group B (n = 10)) until foaling. Foals and placentas were weighed and placental samples were collected...
Stefaniuk-Szmukier M, Piórkowska K, Ropka-Molik K.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 pr...
Merediz EF, Dyer J, Salmon KS, Shirazi-Beechey SP.Fructose can be a suitable carbohydrate supplement for horses before and/or during endurance exercise. In comparison to glucose, the ingestion of fructose results in a lower insulin peak and less marked fluctuations in blood glucose during exercise, potentially avoiding hypoglycaemia-induced exhaustion. Objective: To assess the capacity of the equine small intestine to absorb fructose and to determine the mechanism, molecular structure and properties of equine intestinal fructose transport. Methods: Using PCR-based strategies, RNA isolated from equine small intestine and primers designed to ho...
Bourebaba L, Serwotka-Suszczak A, Bourebaba N, Zyzak M, Marycz K.Hyperactivation of protein tyrosine phosphatase (PTP1B) has been associated with several metabolic malfunctions ranging from insulin resistance, metaflammation, lipotoxicity, and hyperglycaemia. Liver metabolism failure has been proposed as a core element in underlying endocrine disorders through persistent inflammation and highly fibrotic phenotype. Unassigned: In this study, the outcomes of PTP1B inhibition using trodusquemine (MSI-1436) on key equine metabolic syndrome (EMS)-related alterations including inflammation, fibrosis, and glucose uptake have been analyzed in liver explants collect...
Bourebaba L, Kępska M, Qasem B, Zyzak M, Łyczko J, Klemens M, Mularczyk M, Marycz K.Equine metabolic syndrome (EMS) is a steadily growing endocrine disorder representing a real challenge in veterinary practice. As a multifactorial condition, EMS is characterized by three main metabolic abnormalities including insulin resistance, increased adiposity or obesity and hoof laminitis. Adipose tissue dysfunction is recognized as a core pathophysiological determinant of EMS, as it strongly participates to lipotoxicity and systemic metaflammation, both of which have been closely linked to the development of generalized insulin resistance. Besides, sex hormone binding globulin (SHBG) i...
Menzies-Gow NJ.Certain individual animals appear predisposed to recurrent pasture-associated laminitis, but the exact mechanisms underlying their predisposition remain a fundamental question in laminitis research. The risk of endocrinopathic laminitis can be reduced if steps are taken to improve insulin sensitivity and reduce inflammation using strategies based on exercise and diet. Exercise has been shown to reduce insulin resistance and suppress inflammation, and dietary manipulation can significantly affect insulin sensitivity.
Snow DH, Rose RJ.The alteration in plasma concentration of a number of hormones was investigated following an 80 km endurance ride. A marked rise in plasma cortisol levels occurred in all 17 animals investigated. Although decreased glucose levels did not occur in all animals, insulin levels fell in all horses examined. A high correlation (r = 0.89) was found between post ride glucose and plasma insulin concentrations. The plasma levels of both noradrenaline and adrenaline were significantly elevated post ride.
Box JR, McGowan CM, Raekallio MR, Mykkänen AK, Carslake H, Karikoski NP.Obesity and insulin dysregulation (ID) predispose horses to laminitis. Determination of management practices or phenotypic markers associated with ID may benefit animal welfare. Objective: Determine ID status of a population of Finnhorses using an oral sugar test (OST) and compare phenotypes and management factors between ID and non-ID Finnhorses. Methods: One hundred twenty-eight purebred Finnhorses ≥3 years of age. Methods: Owners were recruited using an online questionnaire regarding signalment, history, feeding, and exercise of their horses. Selected contributing stables within a prede...
Leung YH, Kenéz Á, Grob AJ, Feige K, Warnken T.Sphingolipids modulate insulin sensitivity in mammals. Increased synthesis of ceramides is linked to decreased insulin sensitivity of tissues. Conversely, activation of the insulin signaling pathway can downregulate ceramide synthesis. Elucidating the association between sphingolipid metabolism and insulin response during oral glucose testing may help explain the pathophysiology of insulin dysregulation in horses. Objective: Horses with insulin dysregulation will have a plasma sphingolipid profile characterized by increased ceramide concentrations. The plasma sphingolipid profile will have dec...
Boshuizen B, Moreno de Vega CV, De Maré L, de Meeûs C, de Oliveira JE, Hosotani G, Gansemans Y, Deforce D, Van Nieuwerburgh F, Delesalle C.Aleurone, a layer of the bran fraction, is deemed to be responsible for the positive health effects associated with the consumption of whole-grain products. Studies on rodents, pigs, and humans report beneficial effects of aleurone in five main areas: the reduction of oxidative stress, immunomodulatory effects, modulation of energy management, digestive health, and the storage of vitamins and minerals. Our study is the first aleurone supplementation study performed in horses. The aim of this study was to investigate the effect of an increase in the dose levels of aleurone on the postprandial g...
Tóth B, Auth A, Rompos L, Bakos Z.Gastrointestinal and other systemic diseases of Equidae are often characterised by partial or complete inappetence. The catabolic processes may lead to lipid mobilisation and other metabolic disturbances. Evidence from earlier studies has revealed that during feed deprivation/inappetence, the conjugation of bilirubin is reduced causing a substantial rise of the total bilirubin and its unconjugated fraction. Objective: We hypothesised that during feed deprivation, the serum concentration of free fatty acids (FFA), triglycerides (TG), blood urea nitrogen (BUN), total bilirubin (tBIL), total bile...
Mastro LM, Adams AA, Urschel KL.Equine pituitary pars intermedia dysfunction (PPID) has been associated with reduced insulin sensitivity in comparison with younger adult horses; however, the difference in insulin sensitivity between horses with PPID and aged-matched controls has not been well characterized. The objective of the study was to determine if aged horses with PPID had reduced insulin sensitivity and alterations in the insulin-mediated signaling pathways in the skeletal muscle when compared with healthy aged horses. Isoglycemic hyperinsulinemic clamp procedures were conducted in 12 horses that were classified as ei...
Firshman AM, Valberg SJ, Baird JD, Hunt L, DiMauro S.To determine insulin sensitivity, proportions of muscle fiber types, and activities of glycogenolytic and glycolytic enzymes in Belgians with and without polysaccharide storage myopathy (PSSM). Methods: 10 Quarter Horses (QHs) and 103 Belgians in which PSSM status had been determined. Methods: To determine insulin sensitivity, a hyperinsulinemic euglycemic clamp (HEC) technique was used in 5 Belgians with PSSM and 5 Belgians without PSSM. Insulin was infused i.v. at 3 mU/min/kg for 3 hours, and concentrations of blood glucose and plasma insulin were determined throughout. An i.v. infusion of g...
Rijnen KE, van der Kolk JH.To acquire reference range values indicative of glucose metabolism by use of the hyperglycemic clamp technique in healthy horses and evaluate the usefulness of the euglycemic hyperinsulinemic clamp technique in healthy horses and ponies. Methods: Dutch Warmblood horses and 4 Shetland ponies. Methods: The hyperglycemic clamp technique was used for quantification of the sensitivity of beta cells to exogenous glucose infusion in horses. The euglycemic hyperinsulinemic clamp technique was used to determine the sensitivity and responsiveness of tissues to exogenous insulin in horses and ponies. Res...
Haffner JC, Eiler H, Hoffman RM, Fecteau KA, Oliver JW.Sustained dexamethasone administration to horses results in insulin resistance, which may predispose them to laminitis. A single dose of dexamethasone is commonly used as a diagnostic aid, yet the effect of a single dose of dexamethasone on glucose homeostasis in horses is not well defined. The objective of this study was to characterize the change in glucose dynamics over time in response to a single dose of dexamethasone. A combined glucose-insulin tolerance test (CGIT) was performed on 6 adult geldings before and at 2, 24, and 72 h postdexamethasone (40 microg/kg of BW, i.v.); a minimum of ...
van der Kolk JH, Heinrichs M, van Amerongen JD, Stooker RC, in de Wal LJ, van den Ingh TS.To determine size and weight of the pituitary gland and associations between pituitary gland size and weight and sex and age in horses without clinical signs associated with pituitary pars intermedia adenoma (PPIA) and horses and ponies with PPIA. Methods: Pituitary glands from 100 horses without clinical signs of PPIA and 19 horses and 17 ponies with PPIA. Methods: Pituitary glands were weighed, measured, and examined histologically by use of H&E stain. Masson trichrome and periodic acid-Schiff staining were used, when appropriate. Histologic lesions in the pars intermedia, pars distalis,...
