Topic:Cholesterol
Cholesterol in horses is a lipid molecule found in the blood that plays a role in various physiological processes, including cell membrane structure and hormone synthesis. It is obtained from dietary sources and synthesized in the liver. Cholesterol levels in horses can be indicative of metabolic health and are influenced by factors such as diet, age, and activity level. Measuring cholesterol concentrations can assist in assessing the nutritional status and detecting metabolic disorders in equines. This page aggregates peer-reviewed research studies and scholarly articles that explore the metabolism, regulation, and clinical implications of cholesterol in equine health.
Content of meiosis activating sterols in equine follicular fluids: correlation to follicular size and dominance. Meiosis activating sterols (MAS) are pre-cholesterol sterols that can be isolated from follicular fluid (FF-MAS) or testes (T-MAS). Meiosis activating sterols trigger the resumption of meiosis in cultured meiotically competent oocytes. In the present work MAS, cholesterol and progesterone were assayed by HPLC in follicular fluids collected from pony mares at fixed days after the last ovulation. Follicles were divided into two groups according to whether they were aspirated before or after Day 17 after the last ovulation. The latter group was further divided according to whether the follicle di...
Lipid phase separation correlates with activation in platelets during chilling. When human platelets are chilled below 22 degrees C, they spontaneously activate, a phenomenon that severely limits their storage life. It has previously been proposed that there is a correlation between cold-induced platelet activation and passage of the membranes through a liquid-crystalline to gel phase transition. Because animal models are essential for developing methods for cold storage of platelets, it is necessary to investigate such a correlation in animal platelets. In this work, horse platelets were used as a model, and it was found that cold-induced morphological activation is rela...
Equine P450 cholesterol side-chain cleavage and 3 beta-hydroxysteroid dehydrogenase/delta(5)-delta(4) isomerase: molecular cloning and regulation of their messenger ribonucleic acids in equine follicles during the ovulatory process. The preovulatory LH rise is the physiological trigger of follicular luteinization, a process during which the synthesis of progesterone is markedly increased. To study the control of follicular progesterone biosynthesis in mares, the objectives of this study were to clone and characterize the equine cholesterol side-chain cleavage cytochrome P450 (P450(scc)) and 3 beta-hydroxysteroid dehydrogenase/Delta(5)-Delta(4)-isomerase (3 beta-HSD), and describe the regulation and cellular localization of their transcripts in equine follicles during hCG-induced ovulation. Complementary DNA cloning and pr...
Detection of steroidogenic acute regulatory protein in equine ovaries. A steroidogenic acute regulatory (StAR) protein has been identified in several species as a probable important rate-limiting step in steroidogenesis. This protein is believed to be responsible for transporting cholesterol from the outer to the inner mitochondrial membrane. It is known that equine chorionic gonadotrophin (eCG) stimulates steroidogenesis in the corpora lutea of early pregnant mares and that eCG also upregulates StAR mRNA in bovine ovaries. In the present study, ovarian tissue from cyclic and early pregnant mares was immunostained to detect the distribution of the StAR protein. W...
Six intestinal microflora-associated characteristics in sport horses. The aim of this study was to investigate 6 microflora-associated characteristics (MACs) in faecal samples from horses and to compare the results with baselines previously established in other mammals. A MAC is defined as any anatomical structure, physiological, biochemical or immunological characteristic in a host, which has been acted on by microorganisms. When the active microbes are absent, as in germ-free animals and healthy newborn organisms, the corresponding characteristic is defined as germ-free animal characteristic (GAC). The MACs studied were degradation of mucin, conversion of chol...
Effect of feeding thoroughbred horses a high unsaturated or saturated vegetable oil supplemented diet for 6 months following a 10 month fat acclimation. This study looked at the effect of feeding diets supplemented with either a predominantly saturated or unsaturated vegetable oil over a prolonged period to exercising horses. Eight Thoroughbred horses were assigned to 2 diet treatments and for 10 months were fed Timothy hay and oats, together with a fortified sweet feed supplemented with either a predominantly unsaturated (Un) or a saturated (S) vegetable oil so that approximately 19% DE (Digestible Energy) came from dietary fat and approximately 12% from either the Un or S source (AC). An increased amount of Un or S fortified sweet feed, repl...
Dietary fat supplementation and equine plasma lipid metabolism. Feeding of a fat-rich diet to horses may enhance the flux of fatty acids, in the form of triacylglycerols (TAG), through the circulation into skeletal muscle. This hypothesis was tested indirectly by measuring the concentration of plasma TAG and the activity of lipoprotein lipase (LPL) in post heparin plasma. Six mature horses were fed a high-fat or a control diet according to a crossover design with feeding periods of 6 weeks. The control diet contained 1.5% fat in the dry matter and the high-fat diet 11.8%. The high-fat diet was formulated by adding soybean oil to the control diet at the exp...
Effect of cholesterol on the motility and plasma membrane integrity of frozen equine spermatozoa after thawing. The aim of the present study was to investigate the cryoprotectant properties of cholesterol after incorporation into the plasma membranes of equine spermatozoa. A cholesterol-methyl-beta-cyclodextrin complex was used to alter sperm plasma membrane cholesterol content. Ejaculates from six stallions were centrifuged in a non-fat skimmed milk glucose-sucrose extender (MK) or a modified Tyrode's medium (TALP). The sperm pellets were resuspended in the appropriate extender with or without added cholesterol (0.125 mmol cholesterol-methyl-beta-cyclodextrin complex l(-1)) and incubated at 24 degrees ...
Effect of parturition on levels of vitamins A and E and of beta-carotene in plasma and milk of mares. The objective of this study was to investigate in mares the effect of parturition on plasma and milk levels of retinol, beta-carotene, alpha-tocopherol and cholesterol over 12 weeks around parturition. In blood plasma of horses around parturition an increase of all these components was observed. This increase was most impressive in beta-carotene (P<0.05) and less pronounced for vitamin E, vitamin A and cholesterol. The magnitude of increase around parturition corresponded well with the magnitude of accumulation in colostrum; levels of beta-carotene in colostrum were 65 times higher compared...
Effect of hypothyroidism on blood lipid concentrations in horses. To measure and compare concentrations of selected blood lipids before and after thyroidectomy in horses. Methods: 5 healthy adult mares. Methods: Mares were confirmed to be euthyroid. Thyroidectomy was performed, and hypothyroidism was confirmed. Selected blood lipid variables were measured before hypothyroidism was induced and weekly for 4 weeks after induction. Plasma concentrations of very low-density lipoprotein (VLDL), low-density lipoprotein (LDL), serum triglyceride (TG), total cholesterol (TC), and nonesterified fatty acid (NEFA) were measured. The composition of VLDL and LDL also was ...
Effect of a supplementary dietary evening primrose oil mixture on hoof growth, hoof growth rate and hoof lipid fractions in horses: a controlled and blinded trial. The lipid chemistry of the normal equine hoof, together with the effect of oral supplementation with an evening primrose oil mixture (EPOM) on its growth, growth rate and lipid content was assessed in a controlled and blinded feeding trial at the Defence Animal Centre. Twelve horses were paired as closely as possible according to sex, age, weight, height and colour and then one from each pair was randomly allocated to treatment or control groups. The treatment group received 30 ml of oral EPOM/day, otherwise the nutrition and management regimes were the same for all horses. No significant diff...
Computed tomography of cholesterinic granulomas in the choroid plexus of horses. Cholesterinic granulomas are tumor-like masses in the choroid plexuses of horses. This report describes the computed tomographic findings in four horses with cholesterinic granulomas, including the clinical and the pathologic features. All four horses had bilateral cholesterinic granulomas in the lateral ventricles. Computed tomographic images clearly delineated the masses, the opacity of the granulomas, and the enhancement pattern after intravenous bolus injection of contrast medium; these factors varied considerably. Additional CT findings were symmetric or asymmetric widening of the lateral...
Prostasome-like particles in stallion semen. Human semen contains membranous vesicles called prostasomes. They are secreted by the prostate gland and contain large amounts of cholesterol, sphingomyelin, and Ca2+. Prostasomes enhance the motility of ejaculated spermatozoa and are involved in a number of additional biological functions. No prostasome-like vesicles have been described in horse semen up to now. We have demonstrated the presence of prostasome-like vesicles in the equine semen and characterized them as to size, morphology, and lipid composition; we have found that they are similar to human prostasomes in many respects. We prop...
Metabolic adaptation to fat-supplemented diet by the thoroughbred horse. Following 10 weeks of fat supplementation a group of aerobically trained thoroughbred horses exhibited a significant decrease in postprandial plasma triacylglycerol concentration. This decrease was associated with a mean 50% increase in plasma total lipase activity following pentosan polysulfate administration and an increase in postprandial plasma cholesterol concentration. A significant increase in the activity of muscle citrate synthase (EC 4.1.3.7), expressed as a ratio to the total fractional area occupied by type I and type IIa muscle fibres, was also observed. No significant change in t...
Plasma alpha-tocopherol, beta-carotene, and lipid levels in semi-free-ranging Przewalski horses (Equus przewalskii). Circulating concentrations of alpha-tocopherol, beta-carotene, and lipids were quantified in 19 Przewalski horses (Equus przewalskii) inhabiting the steppes of Ukraine during June 1991. Foals (n = 3) had lower mean plasma alpha-tocopherol (4.7 micrograms/ml) and beta-carotene (0.3 microgram/ml) levels than did adults (n = 16; 6.6 and 0.7 micrograms/ml, respectively) and higher mean cholesterol concentrations (1.42 vs. 0.98 mg/ml). Mean triglyceride levels did not differ between foals and adults (0.46 mg/ml). Alpha tocopherol concentrations were substantially higher than those considered normal...
Daily fluctuations of haematology and blood biochemistry in horses fed varying levels of protein. Changes in the plasma biochemistry of 12 stallions were studied over seven 24 h periods. Twelve healthy male horses of 4 different breeds (Thoroughbred [TB], Anglo-Arabo-Sardo [AAS], Avelignese [Av] and Maremmano [M]) were divided into 3 experimental groups and fed with an isoenergetic maintenance ration with different protein levels. The same amount of food was given daily at 0730 and 1930 h. After 20 days of pretrial, a series of 6 blood samples were collected daily from the jugular vein every 4 h for 7 days. The samples were analysed for packed cell volume (PCV), haemoglobin, plasma glucose...
Effects of phosphatidylserine and cholesterol liposomes on the viability, motility, and acrosomal integrity of stallion spermatozoa prior to and after cryopreservation. Computer-assisted motion analyses (CASA) and flow cytometry were used to evaluate stallion spermatozoa prior to and after cryopreservation. Spermatozoa were pretreated with: (1) Hepes-buffered medium (SHB); (2) phosphatidylserine (PS) liposomes; or (3) liposomes composed of both PS and cholesterol (PSCH) prior to dilution in either SHB or skim milk-egg yolk extender (SMEY). After cooling to 5 degrees C in SHB, PS and PSCH pretreatment (23%). Spermatozoal motion parameters were higher for spermatozoa diluted in SMEY than dilution in SHB. In Experiment 2, motion parameters were compared for sper...
In vitro Catabolism of very low density lipoproteins from horse (Equus caballus) by the action of autologous lipoprotein lipase. Incubation of equine very low density lipoproteins with lipoprotein lipase isolated from horse postheparin plasma resulted in the formation of lipoproteins of a higher density. Lipoproteins isolated after incubation and plasma lipoproteins had a different chemical composition and triacylglycerol fatty acid pattern. In vitro-obtained low density lipoproteins contained substantially more phospholipids and triacylglycerols but significantly less cholesteryl esters than native low density lipoproteins. Comparing the triacylglycerol fatty acid pattern of plasma very low density lipoproteins and in ...
Effects of lipoprotein, equine luteinizing hormone, equine follicle-stimulating hormone, and equine prolactin on equine testicular steroidogenesis in vitro. A stallion testicular cell incubation system was developed and used to investigate the regulation of steroidogenesis in stallion testes. Cells isolated from testes of 2- to 4-year-old stallions (n = 6) were cultured for 12 hours in a defined medium with and without varying doses of lipoprotein, equine luteinizing hormone (eLH), human chorionic gonadotropin (hCG), equine follicle-stimulating hormone (eFSH), and/or equine prolactin (ePRL). Estrogen conjugate (EC), testosterone (T), and estradiol-17 beta (E2) production were determined by RIA. Increasing doses of lipoprotein significantly (P <...
Neurological manifestation of cholesterinic granulomas in three horses. Cholesterinic granulomas have been previously reported as an incidental post mortem in horses. Three adult horses with diencephalic dysfunction due to cholesterinic granulomas are described. All the horses exhibited profound depression, somnolence and reluctance to move. One horse experienced generalised seizures. Cerebrosinal fluid was xanthochromic with an elevated total protein in two of the cases evaluated. The large cholesterinic granulomas caused expansion of the lateral ventricle and secondary hydrocephalus due to the build up of cerebrospinal fluid behind the mass. Cholesterinic granul...
Follicular fluid lipoproteins in the mare: evaluation of HDL transfer from plasma to follicular fluid. Using a density gradient ultracentrifugal procedure, we have separated equine plasma and follicular fluid high-density lipoproteins (HDL). The density distribution of the follicular fluid HDL was clearly displaced towards the highest densities in comparison with that of plasma HDL. Similarly, an analysis of size distributions showed a decrease in follicular fluid HDL diameters (4.2 to 9.2 nm) compared to plasma HDL (5.5 to 9.5 nm). HDL were isolated into three subfractions on the basis of the disposition of the Sudan Black stained bands in the centrifuge tubes. Concentrations of each subfracti...
The horse feto-placental unit. In the pregnant mare two different groups of oestrogens are produced by the placenta. The precursor of "classical" oestrogens (oestrone, oestradiol-17 beta and oestradiol-17 alpha) is dehydroepiandrosterone which originates from the fetal gonads. The ring B unsaturated oestrogens (equilin and equilenin and their derivatives) derive from farnesyl pyrophosphate by a pathway not involving cholesterol.
The effect of added dietary soybean oil on vitamin E status of the horse. Fourteen 2-yr-old Quarter Horses and Quarter Horse x Thoroughbreds were randomly assigned to either a control (CTRL) diet or a diet supplemented with 6.4% soybean oil (SBO). The amounts of both diets that were fed met current NRC nutrient requirements and were isoenergetic with similar nutrient:energy ratios. Venous blood samples (20 mL) were taken at d 0, 30, 60, and 90 of the experiment and analyzed for serum alpha-tocopherol, serum cholesterol, and serum triglyceride. The sum of serum cholesterol and serum triglyceride values was used as an estimate of serum total lipid. The ratio of serum ...
Plasma lipid transport in the horse (Equus caballus). 1. Equine plasma contains lipoproteins corresponding to very low density (VLDL), low density (LDL) and high density lipoproteins (HDL). 2. HDL accounts for approximately 60% of plasma lipoprotein mass and consists of a single population of particles. 3. LDL is heterogeneous comprising three discrete subfractions. 4. Two proteins are found in the region of apolipoprotein (apo) B-100 in VLDL and LDL and a third similar to apoB-48 is in VLDL. 5. Lecithin:cholesterol acyl transferase is active in plasma and hepatic lipase and lipoprotein lipase are evident in post-heparin plasma. 6. There is no si...
Diffuse cerebral encephalopathy associated with hydrocephalus and cholesterinic granulomas in a horse. Cholesterinic granulomas, commonly found at necropsy in aged horses, may cause neurologic signs by obstructing the interventricular foramina, resulting in hydrocephalus. Diffuse cerebral disease in horses may not always result in rapid progression of clinical signs. Intermittency of neurologic signs may be associated with intermittent increases in CSF pressure.
Effects of pregnancy and lactation on plasma lipid and lipoprotein concentrations, lipoprotein composition and post-heparin lipase activities in Shetland pony mares. The incidence of hyperlipaemia in ponies is highest in mares in late gestation and then early in lactation. Plasma lipid and lipoprotein concentrations were measured to establish the metabolic basis for this and the lipoprotein composition of six healthy Shetland ponies was analysed before pregnancy, in the last six weeks of gestation and one month after foaling. In the pregnant ponies, the concentrations of cholesterol and triglyceride were significantly increased (both P < 0.05) because of increased concentrations of high density lipoproteins (HDL) and very low density lipoproteins (VLDL)...
High density lipoprotein metabolism in the horse (Equus caballus). 1. Apolipoprotein A-I dependent lecithin:cholesterol acyl transferase (LCAT) activity was identified in equine lipoprotein deficient plasma (LPDP). 2. LCAT activity showed no breed or sex variation, and was unaltered postprandially. 3. There was no significant cholesteryl ester transfer activity in equine LPDP. 4. Hydrophobic interaction chromatography on phenyl sepharose failed to unmask transfer activity or identify an inhibitor of cholesteryl ester transfer. 5. In 12 Shetland ponies, plasma high density lipoprotein (HDL) concentrations were positively correlated with those of triglyceride, ...
Lipids and calcium uptake of sperm in relation to cold shock and preservation: a review. When sperm of the ram, bull, boar and stallion are cold-shocked by rapid cooling to near freezing point, motility and metabolic activity are irreversibly depressed and the acrosome and plasma membrane disrupted. Ram sperm become susceptible to cold shock in the proximal corpus region of the epididymis when the cytoplasmic droplet has moved backwards to the distal portion of the sperm midpiece. The membrane constituents phospholipids and cholesterol are important in cold shock which causes loss of lipid from sperm. The susceptibility of sperm to cold shock is linked with a high ratio of unsatur...
Turbidity of hyperimmune equine antivenom: the role of phenol and serum lipoproteins. Twenty batches of polyvalent antivenom produced at the Instituto Clodomiro Picado were analyzed for turbidity, both before and after freezing-thawing and lyophilization. Eight batches became turbid upon freezing-thawing, and this change correlated with high levels of cholesterol, triglycerides and lipoproteins, especially beta-lipoprotein. Since normal horse serum does not become turbid after freezing-thawing, despite the fact that it has high lipoprotein levels, the possibility was raised that phenol, used as a preservative during serum fractionation, might affect lipoproteins, inducing the a...
Effects of unopposed conjugated equine estrogen on lipoprotein composition and apolipoprotein-E distribution. Administration of conjugated equine estrogen to 31 postmenopausal women for 3 months produced 14.6% and 9.4% decreases in low density lipoprotein cholesterol (LDL-C) and apolipoprotein-B (apoB), and 11.5%, 12.7%, and 9.6% increases in high density lipoprotein cholesterol (HDL-C), apoA-I and apoA-II, respectively. Phospholipids of HDL2 and HDL3 were increased 57.9% and 19.3%, respectively, while relatively small increases in cholesterol of the two subfractions were not significant. Compositions of LDL and HDL and its subfractions were altered substantially with estrogen treatment. The proportio...