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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.
Muscle characteristics in Thoroughbreds of different ages and sexes. Muscle biopsies were taken from the middle gluteal muscle in 163 healthy Thoroughbreds aged one to six years. The horses were separated according to sex and divided into four different age groups (one, two, three and four to six years). Muscle biopsies were analysed for fibre type (I, IIA and IIB), and the enzyme activities of citrate synthase, 3-OH-acyl-CoA dehydrogenase, lactate dehydrogenase and hexokinase were measured. The percentage of Type I fibres of all horses increased with age, irrespective of sex (from 9 to 16 per cent). The percentage of Type IIA fibres varied with age and sex, in...
Circulating antagonist of luteinizing hormone in association with infertility in stallions. Using a LH radioligand receptor assay (RRA) previously validated for use in serum and an equine monoclonal RIA, we have distinguished a subset of subfertile stallions with an elevated RRA/RIA ratio. After purification of the active moiety by anion exchange chromatography and immunoprecipitation with the equine LH (eLH) monoclonal antibody, RRA activity remained in the supernatant. This activity was also recognized by a polyclonal LH antibody (GDN 15) with wide cross-species recognition. This active fraction was further purified by gel filtration chromatography and shown to displace labeled eLH...
Acute hemolytic anemia after oral administration of L-tryptophan in ponies. The hematologic and pathologic effects of orally administered L-tryptophan and indoleactic acid and of L-tryptophan administered IV were studied in ponies. Sixteen adult Shetland ponies were allotted into 4 experimental groups. Group 1 consisted of 5 ponies (1-5) given 0.6 g of tryptophan/kg of body weight in a water slurry via stomach tube. Group 2 included 4 ponies (6-9) given 0.35 g of tryptophan/kg orally. Group-3 ponies (10-13) were given 0.35 g of indoleacetic acid/kg orally. Group 4 consisted of 3 ponies (14-16) given a single 4-hour IV infusion of 0.1 g of tryptophan/kg. Restlessness, ...
Fibronectin concentration in plasma of mares and neonatal foals. Plasma fibronectin concentrations were measured in clinically healthy mares and their neonatal foals, using a modified human fibronectin competitive enzyme-linked immunosorbent assay. Ranges of plasma fibronectin were established in clinically healthy horses, and the assay was reliable and reproducible. Plasma fibronectin concentrations were similar in mares and foals, both before and after colostrum ingestion.
Change in the amount of epsilon-hexosyllysine, UV absorbance, and fluorescence of collagen with age in different animal species. Skin and aorta collagen specimens of Wistar rats, white mice, beagle dogs, cats, horses, and human necropsies of different ages were examined with respect to the content of glycated products. The data presented show that (a) glycation and accumulation of the chromophore(s) are comparable in collagen samples from different species of comparable age; (b) glycation and pigmented accumulation increase markedly during the first 5-10 years of age; (c) the extent of glycation is different in different tissues (in particular, glycation of aortal collagen is about twice that of skin collagen); and (d) ...
Isolation of a major form of pepsinogen from gastric mucosa of horses. In mammalian species studied previously, pepsinogen consisted of biochemically different groups of isozymogens. By use of gel filtration chromatography and electrophoresis, we isolated a predominant pepsinogen from the gastric mucosa of a horse. Peptide mapping with V8 protease revealed differences with its porcine homologue. However, porcine and equine pepsinogens, when activated to pepsin, had a similar pattern of activity when hemoglobin was used as substrate. Those results suggest that differences must exist in the primary structure of the pepsinogens of the 2 species.
Detomidine reduces the plasma catecholamine, but not cortisol concentrations in horses. Single doses of the alpha 2-adrenergic sedative-analgesic drug, detomidine (10 micrograms/kg, n = 7; 20 micrograms/kg, n = 9), were administered IV to adult horses. Plasma concentrations of adrenaline, noradrenaline, the catecholamine metabolites 3,4-dihydroxyphenylglycol (DHPG) and 3,4-dihydroxyphenylacetic acid (DOPAC), and cortisol were determined before the medication and 30 minutes after it. The plasma concentrations of noradrenaline and the catecholamine metabolites decreased significantly after administration of both 10 micrograms/kg and 20 micrograms/kg of detomidine. Plasma adrenaline...
In vitro transport of cycloleucine by equine cecal mucosa. Mucosa obtained from the cecum of healthy horses and incubated in vitro with 0.1 mM cycloleucine could accumulate this amino acid against an apparent concentration gradient after 60 and 120 minutes. Accumulation by the serosal (antiluminal) surface of the tissue was 3 times greater than accumulation by the mucosal (luminal) surface after 120 minutes (P less than 0.001). Cycloleucine accumulation was significantly reduced by Na deprivation after 60 minutes (P less than 0.05) and 120 minutes (P less than 0.01) and by anoxic conditions after 120 minutes (P less than 0.05). Transmucosal flux from ...
Effect of dietary alpha-linolenic acid on endotoxin-induced production of tumor necrosis factor by peritoneal macrophages in horses. A study was conducted to determine whether dietary supplements with alpha-linolenic acid altered the ability of equine peritoneal macrophages to produce tumor necrosis factor (TNF) in response to endotoxin. Peritoneal macrophages were harvested from 6 healthy adult horses before and after the horses were fed a nutritionally balanced ration that contained 8% linseed oil as a source of alpha-linolenic acid. The macrophages were cultured in media containing no additives (control), endotoxin (0.5 to 50 ng/ml), or the calcium ionophore, A23187. Macrophage supernatants were collected after 6 and 24 ...
Detection and identification of loline and its analogues in horse urine. Several kinds of loline-type alkaloids, norloline, loline, N-acetylnorloline, N-acetylloline, N-formylnorloline, N-formylloline and N-methylloline were detected in the urine of race-horses. Furthermore, a new compound of the alkaloids, N-senecioylnorloline, was also found and identified. These compounds were mainly identified by means of gas chromatography-mass spectrometry (GC-MS) and gas chromatography-fourier transform-infrared spectrometry (GC-FT-IR). A certain plant of Gramineae containing four kinds of loline-type alkaloids was found in a bale of hay used for the horse forage. The taxono...
Influence of an omega-3 fatty acid-enriched ration on in vivo responses of horses to endotoxin. Because certain inflammatory processes are dependent on the fatty acid composition of the cellular membrane, dietary manipulations that replace omega-6 fatty acids with omega-3 fatty acids may modify inflammatory responses. We investigated the effect of supplemental dietary linseed oil, containing the omega-3 fatty acid, alpha-linolenic acid, on in vivo responses of horses to endotoxin. One group of horses (n = 6) was fed a control pelleted ration (0% linseed oil), and another group of horses (n = 6) was fed an 8% linseed oil pelleted ration. After 8 weeks of consuming these rations, all horse...
Cloning the cDNA for horse growth hormone and expression in Escherichia coli. A 514 bp cDNA transcript coding for 78% of horse (Equus caballus.) GH has been cloned and sequenced. The deduced amino acid sequence corresponded precisely to that previously obtained by protein sequencing and, in addition, provided new sequence information for the signal peptide. The missing 3' fragment of the cDNA was reconstructed using synthetic oligonucleotides and site-specific directed mutagenesis. The complete cDNA sequence was then inserted into an expression vector (PIN-III-lppp-5) which utilizes a bacterial signal peptide to secrete the expressed product into the periplasmic space o...
Reverse-phase ion-pairing high-performance liquid chromatography of phosphocreatine, creatine and creatinine in equine muscle. A simple, robust and reproducible analytical method for the determination of phosphocreatine (PCr), creatine (Cr) and creatinine (Cn) in equine skeletal muscle is presented. The technique used isocratic reverse-phase ion-pairing high-performance liquid chromatography. Neutralized perchloric acid extracts of equine muscle biopsies were analysed and the values obtained were compared with determinations from an established enzymic procedure. Good resolution of all three metabolites was achieved within a retention time of less than 11 min. Linearity for each metabolite within the concentration ran...
Equine infectious anemia virus and human immunodeficiency virus DNA synthesis in vitro: characterization of the endogenous reverse transcriptase reaction. The endogenous reverse transcriptase reaction of equine infectious anemia virus (EIAV) has been studied, and conditions allowing synthesis of full-length minus-strand DNA have been determined. In contrast to results reported for other retroviruses, synthesis of EIAV full-length minus-strand DNA was not impaired by high concentrations of Nonidet P-40, a nonionic detergent used to make the virion envelope permeable. All components of the reaction were titrated for maximum synthesis of complete minus strands, and a time course under the standardized conditions was determined. Minor subgenomic ban...
Modulation of equine tracheal smooth muscle contractility by epithelial-derived and cyclooxygenase metabolites. The role of epithelium in the modulation of contractile responses to electrical field stimulation (EFS), acetylcholine (ACh), and KCl were studied in vitro in strips of equine tracheal smooth muscle (TSM). EFS with 0.5 ms pulses of voltage (70 V) resulted in frequency dependent contractions of equine TSM that were sensitive to tetrodotoxin (TTX) and atropine. In TSM without epithelium, preincubation with indomethacin significantly potentiated contractile responses to EFS. The potentiating effect of indomethacin on EFS contractions was abolished by the addition of 3 nM prostaglandin E2 (PGE2). ...
Concentrations of arachidonate metabolites, steroids and histamine in preovulatory horse follicles after administration of human chorionic gonadotrophin and the effect of intrafollicular injection of indomethacin. This study investigated the sequence of hormonal changes within the preovulatory follicles of mares. Mares were injected i.v. with 2500 IU human chorionic gonadotrophin (hCG) when a preovulatory follicle of 35 mm in diameter was detected. Fluid was aspirated from preovulatory follicles before (0 h), and 12, 24 and 36 h after administration of hCG. Concentrations of progesterone, prostaglandin (PG) E2, PGF, 6-keto-PGF1 alpha and thromboxane B2 in follicular fluid increased significantly (P less than 0.01) between 0 and 36 h. At 36 h, PGE2 was present in highest concentrations, followed by PGF a...
1H NMR resonance assignments in a paramagnetic heme protein by two-dimensional spectroscopy: heme resonances in equine met-azido myoglobin. Specific heme protons for the majority of resonances in the downfield resolved region of equine met-azido myoglobin have been assigned using solely the two-dimensional 1H NMR experiments NOESY and COSY. Metazido myoglobin provides a useful test case for the applicability of these techniques to paramagnetic proteins for the following reasons. First met-azido myoglobin is a mixed spin-state protein, with significantly shorter relaxation times and broadened lines relative to pure low-spin systems (eg., met-cyano myoglobin). Second, met-azido hemoglobin and met-azido myoglobin are important as mod...
Contribution of delta bilirubin to the interpretation of hyperbilirubinemia in the horse – a pilot study. A study was conducted to examine the relationship of delta bilirubin to traditional bilirubin fractions to determine if delta bilirubin might assist in differentiating causes of hyperbilirubinemia in the horse. A recently introduced thin-film method was used for delta bilirubin determination. Thin-film and the traditional diazo methods were used for determining total, unconjugated, and conjugated bilirubin fractions. Sera from 38 healthy and 85 sick horses were examined.Thin-film serum delta bilirubin determination does not appear to assist in differentiating causes of unconjugated hyperbiliru...
Maternal and umbilical venous plasma lipid concentrations at delivery in the mare. The concentrations and fatty acid composition of the plasma free fatty acid, triacylglycerol and phospholipid fractions were determined in maternal and umbilical cord vein blood samples taken at delivery from 17 mares. Maternal and umbilical vein plasma free fatty acid concentrations were of a similar order and a positive correlation was found between the two levels suggesting that the equine placenta is permeable to fatty acid. Substantial amounts of the essential fatty acids and their longer chain derivatives were seen in both umbilical vein plasma free fatty acid and phospholipid fractions ...
Immunohistolocalization of the carbonic anhydrase isozymes I, II and III in equine salivary glands. The immunolocalization of carbonic anhydrase isozymes in equine salivary glands was investigated for assessment of their biologic functions. In parotid glands, duct segments showed reactivity with CA-I and CA-III. CA-III was selectively located in duct segments, particularly in the basal cells of the interlobular duct. Serous acinar cells were positive for CA-I and CA-II. In submandibular glands, CA-I and CA-II were present in serous demilune and duct segments. CA-II was selectively located in the duct segments, as also noted in the parotid gland. In sublingual glands, CA-I and CA-II were loca...
A combination histochemical stain for equine muscle. The purpose of this study was to find a combination histochemical staining technique for the evaluation of equine skeletal muscle that is reliable and effective, while offering a substantial reduction in the labor and cost involved with currently used individual histochemical methods. Several combinations under varying conditions of pH were studied. The most uniform results were obtained using an acid preincubation step at an optimal pH of 4.2 followed by reduced nicotinamide adenine dinucleotide-tetrazolium reductase (NADH-TR) and the remainder of the acid-ATPase procedure.
Proliferation of chick embryo neuroblasts grown in the presence of horse serum requires exogenous transferrin. We have previously shown that neuroblasts from cerebral hemispheres of 6-day-old chick embryos are able to proliferate when grown in the presence of fetal calf serum. We report here that in the presence of horse serum alone the proliferative rate of neuroblasts is strongly reduced. A high proliferative rate is restored upon the addition of bovine transferrin and to a lesser extent with added FeSO4 or hemin. These findings suggest that the transferrin of horse serum cannot be used by chick neuroblasts in vitro, while bovine transferrin exogenously added is active in promoting cell proliferation...
Assessment of histamine, bradykinin, prostaglandins E1 and E2 and carrageenin as vascular permeability agents in the horse. The vascular leakage induced by histamine, bradykinin, serotonin and prostaglandin E1 and E2 was assessed. The test agents were injected intradermally into the shaved thoracic skin of horses and the vascular leakage estimated either semi-quantitatively by recording the diameter of the lesions or by measuring the actual volume of extravasated plasma in microliters using iodine-125-labelled human serum albumin (125I-HSA) as a marker in the blood plasma. Using the latter method, the vascular leakage induced by carrageenin and the effect of coadministered prostaglandins E1 and E2 upon the vascular...
Pharmacodynamics and pharmacokinetics of miloxicam in the horse. The novel non-steroidal anti-inflammatory drug (NSAID) miloxicam was administered intravenously to six New Forest ponies at a dosage rate of 0.6 mg/kg in a two-part cross-over study. In each part, three horses received miloxicam and three were given a placebo preparation. The actions of miloxicam, compared to placebo, were assessed in a carrageenan-sponge model of acute inflammation. The rise in skin temperature over the site of the acute inflammatory reaction was less in treated ponies, but differences were not statistically significant. Concentrations of the enzymes acid phosphatase (AP) and...
The development of a gas chromatographic/mass spectrometric screening procedure to detect the administration of anabolic steroids to the horse. A screening procedure for anabolic steroid residues in horse urine has been developed based upon solid-phase extraction and gas chromatographic/mass spectrometric analysis in the selected ion mode. For moderate sample throughput the method provides a viable alternative to radioimmunoassay screening and has advantages over the latter technique due to its flexibility, specificity and ability to detect a number of steroids in a single analysis. Full automation of the gas chromatographic/mass spectrometric analysis is an additional feature of the methodology.
Comparative properties of three functionally different but structurally related serpin variants from horse plasma. Three structurally related but functionally different serpins from horse plasma were isolated and characterized. In spite of their identical N-terminal sequences, which show some similarity to that of human alpha 1-proteinase inhibitor, the reactive-centre loops of each of these proteins show extensive variation. Only inhibitor I, with a P1 methionine residue, resembles human alpha 1-PI with regard to (a) similarity of amino acid sequence in the vicinity of the reactive-site peptide bond, (b) broad inhibitory specificity, (c) sensitivity to oxidative inactivation and (d) high rate of reactivit...
Characterization and mapping of melatonin receptors in the brain of three mammalian species: rabbit, horse and sheep. A comparative in vitro binding study. Melatonin receptors were characterized in the brains of three mammals (rabbit, horse and sheep) by an in vitro binding technique, using 2-[125I]iodomelatonin as labelled ligand. Although binding sites for melatonin have been described recently in several vertebrate species (including the sheep), the rabbit and the horse have not been the subject of investigation so far. Apart from characterization, the present report describes receptor distribution in a number of brain regions, thus allowing for direct interspecies comparison under the same methodological conditions. 2-[125I]iodomelatonin labe...
1H and 119Sn magnetic resonance study of the SnIV protoporphyrin IX complex of equine myoglobin. Structure of the porphyrin-binding pocket. Tin protoporphyrin IX (SnPP) is being used in the treatment of hyperbilirubinemia. We have studied the SnPP complex with equine myoglobin (EqMb) by 1H and 119Sn nuclear magnetic resonance spectroscopy (NMR) as a general model for SnPP interaction with hemoproteins. The complex formed from SnPP and EqMb, SnPP.EqMb, was found to have essentially the same porphyrin-binding pocket as EqMbCO, including the same porphyrin orientation in the major form of EqMbCO. 119Sn NMR spectroscopy has been used to demonstrate that the proximal His93F8-metal coordination is likely to be intact in SnPP.EqMb. Minor...
Heart rate, blood biochemistry and performance of horses competing in a 100 km endurance ride. To determine whether a clinical examination was adequate to assess the fitness of horses in an endurance ride, and to characterise the relationship between a clinical assessment of the horse's fitness and its blood biochemistry, 23 horses were monitored before, during and after an 87 to 100 km endurance ride. Blood samples were taken before the ride, at three checkpoints on the ride, immediately after the ride and one day later for the determination of packed cell volume, total protein, lactate, glucose, non-esterified fatty acids, creatine phosphokinase, aspartate aminotransferase and plasma ...
