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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.
Interaction between the sequence of feeding of hay and concentrate, and boiling of barley on feed intake, the activity of hydrolytic enzymes and fermentation in the hindgut of Arabian mares. The interaction between the sequence of feeding of hay and concentrate and the hydrothermal processing of barley in alleviating concentrate effects on intake, and hindgut fermentation in horses was tested. Six Arabian mares (4-10 years of age, 410 ± 35 kg body weight) were used to evaluate the effects of feeding sequence (FS) and type of barley (TB) on intake, and faecal volatile fatty acids (VFA), activities of α-amylase (AA: EC 3.2.1.1), carboxymethyl cellulase (CMCase: EC 3.2.1.4), microcrystalline cellulase (MCCase: EC 3.2.1.91) and general filter paper degrading activity (FPD). Mare...
Immunohistochemical expression of insulin, glucagon, and somatostatin in pancreatic islets of horses with and without insulin resistance. 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...
Modulation of chaperone-like and membranolytic activities of major horse seminal plasma protein HSP-1/2 by L-carnitine. The major protein of horse seminal plasma, HSP-1/2, exhibits membranolytic and chaperone-like activities and plays a crucial role in regulating sperm capacitation. L-Carnitine is a small polar molecule present in high concentrations in mammalian seminal plasma. The present results demonstrate that L-carnitine binds to HSP-1/2 and increases its thermal stability, enhances cooperativity of its chemical unfolding and decreases both chaperone-like and membranolytic activities of this protein. The HSP-1/2-L-carnitine complex exhibits anti-oxidative behaviour by inhibiting the production of hydroxyl...
Prospective pre- and post-race evaluation of biochemical, electrophysiologic, and echocardiographic indices in 30 racing thoroughbred horses that received furosemide. Exercise induced cardiac fatigue (EICF) and cardiac dysrhythmias are well described conditions identified in high-level human athletes that increase in frequency with intensity and duration of exercise. Identification of these conditions requires an understanding of normal pre- and post-race cardiac assessment values. The objectives of this study were to (1) characterize selected indices of cardiac function, electrophysiologic parameters, and biochemical markers of heart dysfunction prior to and immediately after high level racing in Thoroughbred horses receiving furosemide; and (2) create pre...
Inhibition of 5α-reductase alters pregnane metabolism in the late pregnant mare. In the latter half of gestation in the mare, progesterone concentrations decline to near undetectable levels while other 5α-reduced pregnanes are elevated. Of these, 5α-dihydroprogesterone and allopregnanolone have been reported to have important roles in either pregnancy maintenance or fetal quiescence. During this time, the placenta is necessary for pregnane metabolism, with the enzyme 5α-reductase being required for the conversion of progesterone to 5α-dihydroprogesterone. The objectives of this study were to assess the effects of a 5α-reductase inhibitor, dutasteride on pregnane metab...
Survey on basal blood plasma catecholamine concentrations in Martina Franca donkey (Equus asinus). Catecholamines are among the most frequently investigated parameters for studying sympathoadrenal activity in response to stress conditions. Objective: To evaluate basal plasma concentrations of catecholamines (adrenaline, noradrenaline and dopamine) in healthy donkeys. Methods: Cross-sectional study. Methods: Catecholamine concentrations from 440 Martina Franca donkeys were determined: 269 females and 171 entire males, aged from 4 months to 24 years. Animals were subdivided into four age categories: under 12 months old (64 males and 54 females), from 13 to 36 months (56 males and 75 females),...
Excessive Endoplasmic Reticulum Stress Correlates with Impaired Mitochondrial Dynamics, Mitophagy and Apoptosis, in Liver and Adipose Tissue, but Not in Muscles in EMS Horses. 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....
Truncation of the Murine Neonatal Fc Receptor Cytoplasmic Tail Does Not Alter IgG Metabolism or Transport In Vivo. The neonatal Fc receptor (FcRn) is involved in IgG metabolism and transport in placental mammals. However, whether FcRn is responsible for IgG transfer from maternal serum to colostrum/milk is controversial. Interestingly, large domestic animals, such as cows, pigs, sheep, and horses, in which passive IgG transfer is exclusively completed via colostrum/milk, all express an FcRn α-chain that is shorter in the cytoplasmic tail (CYT) than its counterparts in humans and rodents. To address whether the length variation has any functional significance, we performed in vitro experiments using the Tr...
Effects of stacked wedge pads and chains applied to the forefeet of Tennessee Walking Horses for a five-day period on behavioral and biochemical indicators of pain, stress, and inflammation. OBJECTIVE To determine the effects of stacked wedge pads and chains applied to the forefeet of Tennessee Walking Horses on behavioral and biochemical indicators of pain, stress, and inflamation. ANIMALS 20 Tennessee Walking Horses. PROCEDURES Horses were randomly assigned to 2 treatment groups: keg shoes (control; n = 10) or stacked wedge pads and exercise with chains (10). Ten days before treatment application, an accelerometer was attached at the left metatarsus of each horse to record daily activity. Horses were exercised for 20 minutes daily, beginning on day -7. On day 0, exercise ceased,...
Comparison of two methods for measurement of equine adrenocorticotropin. Accurate measurement of equine adrenocorticotropin (ACTH) is important for the diagnosis of equine pituitary pars intermedia dysfunction (PPID). Several radioimmunoassays (RIAs) and chemiluminescent immunoassays (CIAs) are used for measurement of ACTH concentration in horses; whether these methods yield similar results across a range of concentrations is not determined. We evaluated agreement between a commercial RIA and CIA. Archived plasma samples ( n = 633) were measured with both assays. Correlation between the 2 methods was moderate ( r = 0.49, p < 0.001). Bland-Altman analysis reveale...
Estimation of dietary threonine requirement using plasma amino acid concentrations in mature thoroughbreds. The experiment was conducted to estimate dietary threonine (Thr) requirement using plasma amino acid concentrations as a criterion in mature thoroughbreds. Four adult thoroughbreds were used, and a 4 × 4 Latin square design was used for four dietary Thr levels. Plasma Thr concentration was constant until 0.41%, and then increased rapidly with increasing dietary Thr levels. The Thr requirement was estimated to be 67% of lysine with plasma Thr concentration at four Thr levels.
Effect of side of the corpus luteum and pregnancy on estrogen and progesterone receptor expression and localization in the endometrium of mares. The effect of side of corpus luteum on uterine gene expression and protein localization of estrogen receptor α (ERα) and progesterone receptor (PR) in healthy cyclic and pregnant mares 13 days after ovulation (day 0) was investigated. Transcervical biopsies were performed to collect endometrium ipsilateral and contralateral regarding the side of corpus luteum on day 13 post-ovulation in cyclic (n = 6) and pregnant (n = 6) mares. Blood samples were collected daily from day 0 until the day of biopsy for 17β-estradiol (E2) and progesterone (P4) determinations. Receptor expression was d...
The effects of aging on hepatic microsomal scaling factor and hepatocellularity number in the horse. 1. Scaling factor values for the in vitro-in vivo extrapolation of hepatic metabolic clearance for xenobiotics have not yet been determined in horses. Scaling factors were determined by comparing the total protein and or cytochrome (CYP) P450 content in microsomes and cryopreserved hepatocytes against the content in the liver. 2. Microsomal protein per gram of liver (MPPGL) and hepatocellularity number per gram of liver (HPGL) using CYP P450 content method ranged 41-73 mg/gram of liver (mean= 57 mg/gram of liver, n = 39) and 146-320 × 10 cells/g of liver (mean = 227× 10 c...
Development and validation of an ultrahigh performance liquid chromatography-high resolution tandem mass spectrometry quantification method for hypoglycin A and methylene cyclopropyl acetic acid carnitine in horse serum in cases of atypical myopathy. Atypical myopathy (AM) is a fatal disease in horses presumably caused by hypoglycine A (HGA) from ingested maple seeds and its active metabolite methylene cyclopropyl acetic acid (MCPA). The aim of this study was the development and validation of a rapid and simple assay for HGA and MCPA-carnitine in horse serum and its application to authentic samples. Identification and quantification were carried out by ultra high performance liquid chromatography-high resolution tandem mass spectrometry (UHPLC-HRMS/MS) with full-scan/data-dependent MS/MS. Chromatographic separation was performed by isocrat...
Equine in vivo-derived metabolites of the SARM LGD-4033 and comparison with human and fungal metabolites. LGD-4033 has been found in human doping control samples and has the potential for illicit use in racehorses as well. It belongs to the pharmacological class of selective androgen receptor modulators (SARMs) and can stimulate muscle growth, much like anabolic steroids. However, SARMs have shown superior side effect profiles compared to anabolic steroids, which arguably makes them attractive for use by individuals seeking an unfair advantage over their competitors. The purpose of this study was to investigate the metabolites formed from LGD-4033 in the horse in order to find suitable analytical ...
Use of Confocal Microscopy to Evaluate Equine Zygote Development After Sperm Injection of Oocytes Matured In Vivo or In Vitro. Confocal microscopy was used to image stages of equine zygote development, at timed intervals, after intracytoplasmic sperm injection (ICSI) of oocytes that were matured in vivo or in vitro. After fixation for 4, 6, 8, 12, or 16 h after ICSI, zygotes were incubated with α/β tubulin antibodies and human anticentromere antibody (CREST/ACA), washed, incubated in secondary antibodies, conjugated to either Alexa 488 or Alexa 647, and incubated with 561-Phalloidin and Hoechst 33258. An Olympus IX81 spinning disk confocal microscope was used for imaging. Data were analyzed using χ 2 and Fisher's e...
Skeletal muscle from aged American Quarter Horses shows impairments in mitochondrial biogenesis and expression of autophagy markers. Aging is associated with decreased mitochondrial content and function in skeletal muscle, possibly due to compromised biogenesis and autophagic removal of dysfunctional mitochondria. The aim of this study was to compare markers of mitochondrial content and biogenesis and of autophagy between skeletal muscle from young and aged American Quarter Horses. Citrate synthase protein and mtDNA copy number were decreased in triceps brachii (TB) muscle (P<0.05) from aged horses, suggesting an age-related decline in mitochondrial content. Concomitantly, mRNA expression of PGC-1α and TFAM, regulators ...
Endometrial expression of estrogen and progesterone receptors in non-cyclic mares treated only with long-acting progesterone. Administration of progesterone (P4) after estradiol is usually performed to prepare non-cyclic mares as embryo recipients. However, there are successful pregnancy reports after embryo transfer in non-cyclic mares treated only with progestins. The objective of this study was to evaluate endometrial gene expression and immunostaining for estrogen receptor alpha (ERα), beta (ERβ) and progesterone receptor (PR) in seasonal anestrous mares treated with long acting P4 (LA P4). Endometrial tissue from eight seasonal anestrous mares was collected immediately before administration of 1.5 g of LA P4 ...
Skeletal muscle mitochondrial bioenergetics and associations with myostatin genotypes in the Thoroughbred horse. Variation in the myostatin (MSTN) gene has been reported to be associated with race distance, body composition and skeletal muscle fibre composition in the horse. The aim of the present study was to test the hypothesis that MSTN variation influences mitochondrial phenotypes in equine skeletal muscle. Mitochondrial abundance and skeletal muscle fibre types were measured in whole muscle biopsies from the gluteus medius of n = 82 untrained (21 ± 3 months) Thoroughbred horses. Skeletal muscle fibre type proportions were significantly (p < 0.01) different among the three MSTN genotypes and mito...
Influence of spermatozoal lipidomic profile on the cryoresistance of frozen spermatozoa from stallions. The membrane of spermatozoa, which contributes to cellular cryoresistance, contains numerous lipids with a composition that directly affects membrane fluidity and the fertilization process. In light of variations in the degree of sensitivity in equine seminal freezing, this study aimed to correlate equine semen lipids with post-thawing characteristics of spermatozoa. We used ejaculates from 34 stallions, which were evaluated (total motility ≥ 60%), frozen and thawed and reevaluated for motility of spermatozoa, membrane integrity and lipid peroxidation. Lipid extraction of the fresh semen s...
24-Hour Kinetics of Cardiac Troponin-T Using a “High-Sensitivity” Assay in Thoroughbred Chuckwagon Racing Geldings after Race and Associated Clinical Sampling Guidelines. A "high-sensitivity" cardiac troponin-T (hscTnT) assay recently has been validated for use in horses and is a specific biomarker of myocardial damage. Postexercise release kinetics of cTnT utilizing the hscTnT assay have yet to be established in horses. Objective: To determine: (1) cTnT release kinetics in racing Thoroughbreds after a high-intensity 5/8th mile Chuckwagon race; (2) the effects of age on pre- and postrace cTnT concentrations; and (3) sampling guidelines for clinicians evaluating horses presenting after exercise. Methods: Samples were obtained from 38 Thoroughbred geldings aged 5...
Characterization of equine GST A3-3 as a steroid isomerase. Glutathione transferases (GSTs) comprise a superfamily of enzymes prominently involved in detoxication by making toxic electrophiles more polar and therefore more easily excretable. However some GSTs have developed alternative functions. Thus, a member of the Alpha class GSTs in pig and human tissues is involved in steroid hormone biosynthesis, catalyzing the obligatory double-bond isomerization of Δ-androstene-3,17-dione to Δ-androstene-3,17-dione and of Δ-pregnene-3,20-dione to Δ-pregnene-3,20-dione on the biosynthetic pathways to testosterone and progesterone. The human GST A3-3 is the ...
Osteogenic differentiation of equine adipose tissue derived mesenchymal stem cells using CaCl2. Adipose tissue derived mesenchymal stem cells (ASCs) may be used to cure bone defects after osteogenic differentiation. In this study we tried to optimize osteogenic differentiation for equine ASCs using various concentrations of CaCl in comparison to the standard osteogenic protocol. ASCs were isolated from subcutaneous adipose tissue from mixed breed horses. The osteogenic induction protocols were (1) the standard osteogenic medium (OM) composed of dexamethasone, ascorbic acid and β-glycerol phosphate; (2) CaCl based protocol composed of 3, 5 and 7.5mM CaCl. Differentiation and proliferatio...
Procyanidin A2 in the Australian plant Alectryon oleifolius has anthelmintic activity against equine cyathostomins in vitro. There is a need to investigate new methods of controlling cyathostomins in horses due to increasing anthelmintic resistance amongst these parasites. In a previous study we identified the Australian plant Alectryon oleifolius as having anthelmintic activity towards cyathostomins. This study aimed to isolate and identify the bioactive compound(s) responsible for all or part of this anthelmintic activity and quantify its activity in vitro. The condensed tannin procyanidin A2 was isolated from the plant through a process of bioassay guided fractionation and identified using 1D and 2D nuclear magne...
Expression of inflammatory and structural matrix genes in synovial fluid following intra-articular administration of isoflupredone acetate to exercised horses. Intra-articular use of corticosteroids is commonplace in performance horses. Isoflupredone acetate (IPA) is one of four Food and Drug Administration approved corticosteroids for intra-articular use in horses. The lack of published reports describing the efficacy and duration of effects of this drug warrant further study. Objective: To assess the effects of intra-articular administration of IPA on the expression of selected anti- and pro-inflammatory and structural matrix genes following intra-articular administration to exercised Thoroughbred horses and to correlate these effects with drug con...
Pharmacokinetics of inorganic cobalt and a vitamin B12 supplement in the Thoroughbred horse: Differentiating cobalt abuse from supplementation. While cobalt is an essential micronutrient for vitamin B synthesis in the horse, at supraphysiological concentrations, it has been shown to enhance performance in human subjects and rats, and there is evidence that its administration in high doses to horses poses a welfare threat. Animal sport regulators currently control cobalt abuse via international race day thresholds, but this work was initiated to explore means of potentially adding to application of those thresholds since cobalt may be present in physiological concentrations. Objective: To devise a scientific basis for differentiation b...
Seasonal changes in the sperm fatty acid composition of Shetland pony stallions. Spermatozoa contain polyunsaturated fatty acids (PUFA). Cryopreservation damages sperm membranes and they become less functional after thawing. We analysed the lipid composition of spermatozoa from Shetland stallions (n = 15) collected monthly from January to June and hypothesized that sperm lipid patterns change with season. In addition, one ejaculate per month was submitted to cryopreservation. Content of saturated palmytic and stearic acid decreased from January to March (p < 0.001) while content of the PUFA docosapentaenoic (p < 0.001) and arachidonic acid (p < 0.05) and t...
Freezing-induced uptake of disaccharides for preservation of chromatin in freeze-dried stallion sperm during accelerated aging. Nonviable freeze-dried sperm have intact chromatin and can be used for fertilization via intracytoplasmic sperm injection. Freeze-dried sperm preferably should be stored at 4°C or lower, because DNA damage accumulates during storage at room temperature. Disaccharides are known to protect biomolecules both during freezing and drying, by forming a glassy state. Their use is challenging because cellular membranes are normally impermeable for disaccharides. In the current study, we demonstrate that membrane impermeable compounds, including lucifer yellow and trehalose, are taken up by stallion sp...
Mutation of Asn-475 in the Venezuelan Equine Encephalitis Virus nsP2 Cysteine Protease Leads to a Self-Inhibited State. The alphaviral nsP2 cysteine protease of the Venezuelan equine encephalitis virus (VEEV) is a validated antiviral drug target. Clan CN proteases contain a cysteine protease domain that is intimately packed with an S-adenosyl-l-methionine-dependent RNA methyltransferase (SAM MTase) domain. Within a cleft formed at the interface of these two domains, the peptide substrate is thought to bind. The nucleophilic cysteine can be found within a conserved motif, NVCWAK, which differs from that of papain (CGSCWAFS). Mutation of the motif residue, N475, to alanine unexpectedly produced a self-inhibited s...
Effects of body condition score (BCS) on steroid- and eicosanoid-metabolizing enzyme activity in various mare tissues during winter anoestrus. The objective of this study was to determine the activity of steroid- and eicosanoid-metabolizing enzymes in horses with varying BCSs. The BCSs of twenty non-pregnant, anoestrous mares were determined prior to euthanasia, and tissue samples were collected from the liver, kidney, adrenal gland, ovary and endometrium. Cytochrome P450 1A (CYP1A), 2C (CYP2C), 3A (CYP3A) and uridine 5'-diphospho-glucuronosyltransferase (UGT) activities were determined using luminogenic substrates. The MIXED procedure of SAS was used to test the effect of BCS on enzyme activity and differences between tissues. Activ...
