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Topic:Biochemistry
The study of biochemistry in horses encompasses the chemical processes and substances that occur within equine organisms. This field investigates the molecular interactions and pathways that are fundamental to horse physiology, including metabolism, enzyme activity, and genetic expression. Key areas of interest include the examination of metabolic disorders, nutrient absorption, and the biochemical basis of muscle function and energy production. Researchers utilize biochemical analysis to understand health and disease mechanisms in horses, contributing to the development of diagnostic tools and therapeutic strategies. This page gathers peer-reviewed studies and scholarly articles that explore various biochemical processes and their implications for equine health and performance.
LC-MS/MS method for confirmation of recombinant human erythropoietin and darbepoetin alpha in equine plasma. Recombinant human erythropoietin (rhEPO) and darbepoetin alpha (DPO) are protein-based drugs for the treatment of anemia by stimulating red blood cell production. Consequently, they are abused in human and equine sports. To deter their abuse in the horse racing industry, a sensitive and reliable method for confirmation of these agents in equine plasma has been in urgent need. Such a method by LC-MS/MS is described in this paper. The method involved analyte enrichment by immunoaffinity separation using anti-rhEPO antibody linked to magnetic beads, digestion by trypsin, and analysis by LC-MS/MS....
Susceptibility of mammalian deoxyribonucleases I (DNases I) to proteolysis by proteases and its relationships to tissue distribution: biochemical and molecular analysis of equine DNase I. Equine (Equus caballus) deoxyribonuclease I (DNase I) was purified from the parotid gland, and its 1295-bp cDNA was cloned. The mature equine DNase I protein consisted of 260 amino acid residues. The enzymatic properties and structural aspects of the equine enzyme were closely similar to those of other mammalian DNases I. Mammalian DNases I are classified into three types--pancreatic, parotid and pancreatic-parotid-based on their tissue distribution; as equine DNase I showed the highest activity in the parotid gland, it was confirmed to be of the parotid-type. Comparison of the susceptibility ...
Combinatorial selection of a RNA thioaptamer that binds to Venezuelan equine encephalitis virus capsid protein. A phosphorothioate RNA aptamer (thioaptamer) targeting the capsid protein of Venezuelan equine encephalitis virus (VEEV) was isolated by in vitro combinatorial selection. The selected thioaptamer had a strong binding affinity (approximately 7nM) and high specificity for the target protein. For the binding to the protein, the overall tertiary structure of the thioaptamer is required. We introduce two theoretical methods to examine the effect of phosphorothioate modification on the enhancement of binding affinity and one experimental method to examine the nature of the multiple bands of thioapta...
Time- and dose-dependent effects of roundup on human embryonic and placental cells. Roundup is the major herbicide used worldwide, in particular on genetically modified plants that have been designed to tolerate it. We have tested the toxicity and endocrine disruption potential of Roundup (Bioforce on human embryonic 293 and placental-derived JEG3 cells, but also on normal human placenta and equine testis. The cell lines have proven to be suitable to estimate hormonal activity and toxicity of pollutants. The median lethal dose (LD(50)) of Roundup with embryonic cells is 0.3% within 1 h in serum-free medium, and it decreases to reach 0.06% (containing among other compounds 1.2...
A preliminary study of the short circuit current (Isc) responses of sweat gland cells from normal and anhidrotic horses to purinergic and adrenergic agonists. The causal factors of equine anhidrosis have not yet been elucidated but defective electrolyte transport mechanisms in the gland are likely to be involved. To investigate this possibility, experiments were performed on cultured equine sweat gland epithelia from five free-sweating UK horses (3 intact males, 2 mares, aged 2-4 years) and from three free-sweating Singapore horses (1 intact male, 2 mares, aged 3-5 years) and three anhidrotic (Singapore) horses (1 intact male, 1 gelding, 1 mare, aged 3-6 years). Cultured cells from each animal were grown on permeable supports and loaded into Ussing ...
Sequencing of cDNA and proximal promoter of equine hexokinase II gene. In order to investigate the utilization of glucose in equine skeletal muscle, we determined the coding and proximal promoter sequences of the hexokinase type II (HKII) gene in thoroughbred horse, Grevy's zebra and Hartmann's mountain zebra. The deduced amino acid sequence of thoroughbred horse HKII showed 100, 100, 94.4, 92.7 and 92.6% identities with Grevy's zebra, Hartmann's mountain zebra, human, mouse and rat HKIIs, respectively. In equine HKIIs, specific amino acid substitutions, Ile 159 and Arg 610, were found in the potential binding site for glucose. In addition, the nucleotide sequenc...
Efficacy of 2,6-dichlorophenol lure to control Dermacentor nitens. This study was carried out with the objective of evaluating the efficacy of a 2,6-dichlorophenol (2,6-DCP) lure to control Dermacentor nitens (Acari: Ixodidae). Slow-release formulations of the pheromone formulated with and without cypermethrin were prepared. Olfactometer bioassays were used to define the best dose of the pheromone and to evaluate the effect of cypermethrin with 2,6-DCP attractiveness. Sexually active males were released 15 cm from 2 cmx1 cm pieces of polypropylene treated with different odors: 2,6-DCP in a liposphere system (1.5, 30 and 300 microg--without cypermethrin and 30...
Storage of equine red blood cells as a concentrate. The study was undertaken to determine how equine red blood cells (RBCs) survive in storage bags designed for use with human RBCs. Separated RBCs were stored in a routine manner for 35 days and examined every 7 days for storage lesions. Measured parameters included haematology, haemolysis, pH, potassium, lactate, adenosine triphosphate (ATP) and 2,3-diphosphoglycerate (2,3-DPG). All tests were performed in vitro. Haematology did not change significantly. Haemolysis increased during storage but did not exceed human limits. pH and 2,3-DPG decreased, while lactate, potassium and ATP increased. RBC...
Potential involvement of EGF-like growth factors and phosphodiesterases in initiation of equine oocyte maturation. Human chorionic gonadotropin (hCG) was administered to mares in estrus with large, dominant ovarian follicles to initiate follicular and oocyte maturation. Follicular contents were collected at 0, 2, 4 and 6 h after hCG. Epiregulin, amphiregulin and phosphodiesterase (PDE) mRNA contents of granulosa cells (PDE 4D) were determined by reverse transcription and real-time PCR; PDE 3A mRNA content of single oocytes was determined similarly. Copy numbers of mRNA did not increase for PDE 3A or 4D over the time interval studied. Amounts of epiregulin and amphiregulin mRNA were correlated (r=0.98) when...
Expression and nephron segment-specific distribution of major renal aquaporins (AQP1-4) in Equus caballus, the domestic horse. Aquaporins (AQPs) play fundamental roles in water and osmolyte homeostasis by facilitating water and small solute movement across plasma membranes of epithelial, endothelial, and other tissues. AQP proteins are abundantly expressed in the mammalian kidney, where they have been shown to play essential roles in fluid balance and urine concentration. Thus far, the majority of studies on renal AQPs have been carried out in laboratory rodents and sheep; no data have been published on the expression of AQPs in kidneys of equines or other large mammals. The aim of this comparative study was to determ...
Modification of host erythrocyte membranes by trypsin and chymotrypsin treatments and effects on the in vitro growth of bovine and equine Babesia parasites. In the present study, we investigated the effects of protease pretreatments of host erythrocytes (RBC) on the in vitro growth of bovine Babesia parasites (Babesia bovis and B. bigemina) and equine Babesia parasites (B. equi and B. caballi). The selected proteases, trypsin and chymotrypsin, clearly modified several membrane proteins of both bovine and equine RBC, as demonstrated by SDS-PAGE analysis; however, the protease treatments also modified the sialic acid content exclusively in bovine RBC, as demonstrated by lectin blot analysis. An in vitro growth assay using the protease-treated RBC sh...
Automated liquid chromatography-tandem mass spectrometry method for the analysis of firocoxib in urine and plasma from horse and dog. A rugged, sensitive and efficient liquid chromatography-tandem mass spectrometry method was developed and validated for the quantitative analysis of firocoxib in urine from 5 to 3000 ng/mL and in plasma from 1 to 3000 ng/mL. The method requires 200 microL of either plasma or urine and includes sample preparation in 96-well solid phase extraction (SPE) plates using a BIOMEK 2000 Laboratory Automated Workstation. Chromatographic separation of firocoxib from matrix interferences was achieved using isocratic reversed phase chromatography on a PHENOMENEX LUNA Phenyl-Hexyl column. The mobile phase w...
A direct enzyme immunoassay for the measurement of furosemide in horse plasma. A new enzyme immunoassay (EIA) for the measurement of furosemide in horse plasma is described. The lower limit of detection of this EIA method was 7.8 ng/ml. The intra-and inter-assay coefficients of variation ranged from 2.5% to 4.9% and 7.5% to 9.8%, respectively. Cross-reactivity with other compounds was not observed. There was a high correlation (r2=0.987) between the high-performance liquid chromatography and EIA results obtained for furosemide concentrations in horse plasma. These results indicate that the newly developed EIA method is useful for the quantitative analysis of furosemide i...
Effects of dietary glycaemic response after exercise on blood concentrations of substrates used indirectly for muscle glycogenesis. Exercise depletes muscle glycogen stores, which could subsequently impair performance. Muscle glycogen replenishment is determined by substrate availability. Objective: To study the effects of feeding meals of varying glycaemic responses on blood concentrations of substrates used for glycogenesis in horses with exercise-induced glycogen depletion. Methods: In a 3-way crossover study, 7 horses received each of 3 isocaloric diets for 72 h after undergoing glycogen-depleting exercise: 1) a high soluble-carbohydrate diet, which induced a high-glycaemic (HGI) response; 2 and 3) a low soluble-carboh...
Contribution of exercise intensity and duration to training-linked myosin transitions in thoroughbreds. The influence of relevant exercise parameters such as intensity and duration of exercise on the muscular response to training has not been reported in Thoroughbreds. This knowledge may be of great value in practice. Objective: To define the relative contribution of the intensity and duration of exercise on the myosin heavy chain (MHC) response to training in Thoroughbred racehorses. Methods: Six 2-3-year-old Thoroughbreds, following a randomised 6 x 6 latin square design, performed 6 consecutive conditioning programmes of varying lactate-guided intensities and durations. Each programme lasted ...
Enhanced early chondrogenesis in articular defects following arthroscopic mesenchymal stem cell implantation in an equine model. Mesenchymal stem cells (MSCs) provide an important source of pluripotent cells for musculoskeletal tissue repair. This study examined the impact of MSC implantation on cartilage healing characteristics in a large animal model. Twelve full-thickness 15-mm cartilage lesions in the femoropatellar articulations of six young mature horses were repaired by injection of a self-polymerizing autogenous fibrin vehicle containing mesenchymal stem cells, or autogenous fibrin alone in control joints. Arthroscopic second look and defect biopsy was obtained at 30 days, and all animals were euthanized 8 month...
Monocarboxylate transporters (MCT) as lactate carriers in equine muscle and red blood cells. Monocarboxylate transporters (MCT) facilitate the transport of lactate across membranes. In red blood cells (RBC) the transport activity varies interindividually due to differences in the amount of an ancillary protein CD147. Similar variations in muscles could have a great influence on lactate accumulation during exercise. Objective: To study the expression of MCT isoforms and CD147 in the middle gluteal muscle. Methods: Venous blood and muscle biopsy samples were taken from 14 Standardbred horses. Lactate transport activity in RBC and the amounts of MCT1, 2, 4 and CD147 were measured. Result...
Plasma glutamine concentrations in the horse following feeding and oral glutamine supplementation. Pharmacological benefits of glutamine supplementation have been shown in athletically and clinically stressed human subjects. In the horse, infection and intense exercise have also been shown to significantly decrease plasma glutamine concentrations, but little is known on how best to supplement. Objective: To evaluate whether ingestion of different foodstuffs, with or without L-glutamine (G) or a peptide (Pep) containing 31.5% w/w G in a water-stable form, could affect plasma glutamine concentrations (P-GC). Methods: Nine feeds (molassed sugar beet-pulp (mSB); naked oats (nO); commercial mix ...
Synthesis of proglycogen and macroglycogen in skeletal muscle of standardbred trotters after intermittent exercise. The degradation of glycogen and its two forms, proglycogen (PG) and macroglycogen (MG) has been studied in horses performing different types of exercise, but no information is available about the resynthesis of PG and MG after exercise. Objective: To determine the resynthesis of PG and MG in skeletal muscle after intermittent uphill exercise. Methods: At a training camp 9 well-trained Standardbred trotters performed a training session comprising a warm-up period, 7 repeated 500 m bouts of exercise on an uphill slope and a recovery period. Muscle biopsies (m. gluteus medius) for analysis of PG,...
Oral vitamin E supplementation on oxidative stress, vitamin and antioxidant status in intensely exercised horses. Vitamin E is the most commonly supplemented antioxidant in horses; however, previous research is not conclusive as to the recommended level for exercising horses. Objective: To evaluate the effects of 3 levels of vitamin E supplementation on oxidative stress and vitamin/antioxidant status in intensely exercised horses to determine the optimal level of vitamin E supplementation. Methods: Twelve unfit Standardbreds were divided into 3 groups, supplemented orally with 0 (CON), 5000 (MOD), or 10,000 (HI) iu/day of DL-alpha-tocopheryl acetate. The 3 x 3 Latin square design consisted of three 4 week...
Route of carbohydrate administration affects early post exercise muscle glycogen storage in horses. No studies in horses have examined the effect of route of carbohydrate (glucose) administration on the rate of muscle glycogen storage following glycogen-depleting exercise. Objective: Glucose delivery from the gastrointestinal tract limits the rate of muscle glycogen storage following glycogen-depleting exercise. Methods: In a crossover design, 7 fit horses completed treadmill exercise (EX) on 3 occasions to deplete muscle glycogen by approximately 50%. After EX horses received: 1) i.v. glucose infusion (IV; 0.5 g/kg bwt/h for 6 h), 2) oral glucose boluses (OR; 1 g/kg bwt at 0, 2 and 4 h post...
Interval exercise alters feed intake as well as leptin and ghrelin concentrations in standardbred mares. Horses in training tend to become inappetant; however, the mechanism responsible for this training-induced inappetance is not known. Objective: Training and/or ulcers alter the feed intake (FI) and hormonal and/or biochemical (active ghrelin, leptin, glucose, insulin and cortisol) responses to acute high intensity exercise. Methods: Eight Standardbred mares underwent 3 interval exercise tests (IET) and 3 parallel control tests (CON) before (IET1) and after 8 weeks of training (IET2) and after treatment for gastric ulcers (IET3). Plasma samples were taken before (0 min), during (last 10 sec of ...
Thyroid hormone responses to endurance exercise. Limited information exists about changes in circulating thyroid hormone concentrations during prolonged endurance exercise in horses. Objective: To examine the effects of prolonged exercise on serum iodothyronine concentrations in horses performing endurance exercise of varying distances. Methods: Serum concentrations of iodothyronines were measured in horses before and after completion of 40, 56, 80 and 160 km endurance rides (Study 1); daily during a 5 day, 424 km endurance ride (Study 2); and before and for 72 h after completion of a treadmill exercise test simulating a 60 km endurance ride...
Glucose dynamics during exercise: dietary energy sources affect minimal model parameters in trained Arabian geldings during endurance exercise. Glucose regulation is critical for health and exercise performance. Objective: To quantify the effects of exercise and diet on insulin sensitivity (SI), glucose effectiveness (Sg), acute insulin response to glucose (AIRg) and disposition index (DI) in horses. Methods: This study applied the minimal model of glucose and insulin dynamics to exercise-trained Arabian geldings during rest or constant moderate-intensity exercise after 8 weeks adaptation to feeds high in sugar and starch (SS, n = 6) or fat and fibre (FF, n = 6). Horses underwent 2 frequently sampled i.v. glucose tolerance tests (FSIG...
Frusemide results in an extracellular to intracellular fluid shift in horses. Frusemide (Lasix) is commonly used diuretic in horse racing and equine clinical practice. While pharmacology, pharmacodynamics, renal and haematological effects of frusemide have been studied in horses, its effects on the distribution of fluid within the horse remain unknown. Objective: To quantify the effects of frusemide on extracellular and intracellular fluid shifts. Methods: Horses were infused with 1 mg/kg body mass (n = 7) or 2 mg/kg (n = 9) i.v. frusemide. Total body water (TBW), extracellular fluid volume (ECFV) and plasma volume (PV) were measured using D2O, NaSCN and Evans blue dilu...
Recruitment pattern of muscle fibre type during flat and sloped treadmill running in thoroughbred horses. There is little information about the muscle fibre recruitment pattern during sloped and flat track running in Thoroughbred horses. Objective: To examine the glycogen depletion pattern of each muscle fibre type during running on a flat and sloped treadmill. Methods: Thirteen Thoroughbred horses (3-9 years old) were used. They were initially subjected to incremental exercise tests on a treadmill at 10 and 0% inclines in each horse to determine running speed at 90 and 60% VO2max. Needle biopsy samples were obtained from the middle gluteal muscle immediately after the running at 90% VO2max for 4 ...
Uric acid responses to endurance racing and relationships with performance, plasma biochemistry and metabolic alterations. There is limited understanding of the uric acid response to endurance races. Objective: To demonstrate uric acid increments and its relationship to diverse biochemical and performance parameters, in horses subjected to a prolonged effort, with and without presentation of metabolic alterations. Methods: Blood samples were taken from horses the day before, and 5-10 mins after, successfully finishing a 121 km (Assay 1, n = 24) or 164 km endurance race (Assay 2, n = 17), and from 19 animals eliminated by metabolic disorders during several endurance races (Assay 3). Plasma was obtained and determin...
Gene expression profiling in blood cells of endurance horses completing competition or disqualified due to metabolic disorder. Genomics using cDNA microarrays could provide useful information about physiological adaptations and metabolic disorders in endurance horses. Objective: In order to show that genes are modulated in leucocytes in relationship with performance and clinical status of the horses, gene expression in leucocytes, haematological and biochemical parameters were compared between successful and disqualified endurance horses. Methods: Blood samples were collected at rest (TO) and just after a 140-160 km endurance race (T1) in 2 groups of horses: 10 continuing successful (S) and 10 disqualified horses stop...
The effects of dietary N-3 and antioxidant supplementation on erythrocyte membrane fatty acid composition and fluidity in exercising horses. Fatty acid supplementation could modulate erythrocyte membrane fluidity in horses at rest and during exercise, but information is lacking on the effect of exercise. Objective: To assess the effect of exercise with, and without, an oral antioxidant supplementation enriched with n-3 fatty acids on erythrocyte membrane fluidity (EMF) and fatty acid composition in eventing horses. Methods: Twelve healthy and regularly trained horses were divided randomly into 2 groups: group S received an oral antioxidant cocktail enriched in n-3 fatty acid (alphatocopherol, eicosapentaenoic acid [EPA] and docosah...
