Testosterone is a steroid hormone found in horses, primarily produced by the testes in males and, to a lesser extent, by the ovaries and adrenal glands in females. It plays a significant role in the development and maintenance of male reproductive tissues, as well as influencing secondary sexual characteristics and behavior. Testosterone levels can impact muscle mass, bone density, and overall physical condition, and they may vary due to factors such as age, season, and health status. This page compiles peer-reviewed research studies and scholarly articles that explore the production, regulation, and physiological effects of testosterone in equine biology, as well as its implications for behavior and health management in horses.
Satué K, Marcilla M, Medica P, Ferlazzo A, Fazio E.Androgens modulate maternal ovarian activity, embryo implantation and correct placental development. The objective of this study was to establish reference values for testosterone (T), androstenedione (A4) and dehydroepiandrosterone (DHEA) concentrations in pregnant mares. A total of 30 healthy Spanish Purebred mares with an age range of 9.33 ± 3.31 years, were studied during the 11 months of gestation. T, A4 and DHEA concentrations were determined using EIA validated specifically for equines. T increased in the 2nd and 3rd month (P < 0.05), showing a plateau between the 4th and 6th m...
Młodawska W, Grzesiak M, Kochan J, Nowak A.Steroidogenic activity in the equine ovary from birth to puberty has been poorly investigated. This study aimed to examine the capability of the ovarian follicles of prepubertal and pubertal fillies to produce steroid hormones and to evaluate the expression and cellular localization of androgen receptor (AR) in their ovaries. The ovaries of 6-18 month-old fillies were divided into two groups: prepubertal (PrP) - without preovulatory follicle (pF) and corpus luteum (CL), and ovulating/postpubertal (Ov/pB) - with pF and/or CL in at least one of the gonads. Adult mares (Me) were used as a control...
Viljanto M, Hincks P, Hillyer L, Cawley A, Suann C, Noble G, Walker CJ, Parkin MC, Kicman AT, Scarth J.The use of testosterone and its pro-drugs, such as dehydroepiandrosterone (DHEA), is currently regulated in horseracing by the application of international testosterone thresholds. However, additional steroidomic approaches, such as steroid ratios, to distinguish overall adrenal stimulation from drug administrations and an equine biological passport for longitudinal steroid profiling of individual animals could be advantageous in equine doping testing. Thus, DHEA concentrations and related ratios (testosterone [T] to DHEA and DHEA to epitestosterone [E]) were assessed in the reference populati...
Choi TLS, Kwok KY, Kwok WH, Tsoi YYK, Wong JKY, Wan TSM.Anabolic and androgenic steroids (AAS) are banned substances in both human and equine sports. They are often administered intramuscularly to horses in esterified forms for the purpose of extending their time of action. The authors' laboratory has previously reported an UHPLC/HRMS method using quadrupole-Orbitrap mass spectrometer in full scan and parallel reaction monitoring (PRM) mode for the detection of 48 AAS and/or their esters in horse hair. However, two injections were required due to the long duty cycle time. In this paper, an UHPLC/HRMS method using multiplexed targeted MS mode was de...
Beracochea F, Viera MN, Acevedo L, Santiago-Moreno J, Ungerfeld R.In most goat breeds, testosterone serum concentration and semen quality decrease during the nonbreeding season. However, bucks reproductive activity may be stimulated with the administration of equine chorionic gonadotropin (eCG). Therefore, the aim of this study was to determine whether the repeated administration of eCG stimulates the reproductive status of bucks during the nonbreeding season. The study was performed with 19 bucks that were assigned to a group that was treated with eCG (GeCG) and an untreated control group (GCon). The GeCG bucks received an initial dose of 800 IU of eCG (Da...
Gautier C, Schmidt K, Aurich J, Aurich C.The hypothesis in this study was continuous treatment of stallions with the GnRH agonist deslorelin inhibits reproductive functions. A 2-week pre-experimental period was followed by an 11-week deslorelin implant treatment. Stallions received 4.7 (D1, n = 7), or 18.8 mg deslorelin (D2, n = 5) or remained untreated (C, n = 5). Libido, sperm motility, membrane integrity, DNA fragmentation, estrogen receptors, basal plasma testosterone and Anti Muellerian hormone (AMH) concentrations were evaluated once weekly during the treatment period. The testosterone response to the GnRH agonist buserelin a...
Scarlet D, Wulf M, Kuhl J, Köhne M, Ille N, Conley AJ, Aurich C.Anti-Müllerian hormone (AMH) has gained increasing interest as a biomarker for assessment of gonadal activity. The ability to predict the ovarian follicular reserve of prepubertal female horses (fillies) or to identify stallions with testicular pathologies already during their prepubertal life has not been analyzed so far. Both would help to select fertile horses and reduce costs associated with keeping animals. The objectives of the present study were to (1) assess AMH, LH, FSH, progesterone (females) and testosterone (males) dynamics in prepubertal horses from birth onwards and (2) determin...
Ellerbrock RE, Canisso IF, Lima FS, Shipley CF, Thompson DL, Conley AJ, Kline KH.The objectives of this study were to determine the concentrations of reproductive and metabolic hormones during the peripubertal period and to assess their relationship with testicular development and body fat deposition. Blood samples were collected from 23 healthy Standardbred colts every four weeks for twelve months. Colts were weighed monthly, and percent of body fat and testicular volume estimated by ultrasound. Onset of puberty was determined as the month when testosterone was two standard deviations above the previous mean. Plasma FSH, LH, leptin, estradiol-17β, androstenedione, IGF-1,...
Jeannerat E, Marti E, Berney C, Janett F, Bollwein H, Sieme H, Burger D, Wedekind C.The major histocompatibility complex (MHC) has repeatedly been found to influence mate choice of vertebrates, with MHC-dissimilar mates typically being preferred over MHC-similar mates. We used horses (Equus caballus) to test whether MHC matching also affects male investment into ejaculates after short exposure to a female. Semen characteristics varied much among stallions. Controlling for this variance with a full-factorial within-subject experimental design, we found that a short exposure to an MHC-dissimilar mare enhanced male plasma testosterone and led to ejaculates with elevated sperm nu...
Robles M, Dubois C, Gautier C, Dahirel M, Guenon I, Bouraima-Lelong H, Viguié C, Wimel L, Couturier-Tarrade A, Chavatte-Palmer P.Primiparous mares are known to produce smaller foals than multiparous mares. This difference seems to be partly explained by the reduced exchange surface and volume of the placental villi in primiparous compared to multiparous placentas. The effect of maternal parity on foals' post-natal growth, metabolism and sexual maturation, however, has been given little consideration. The objectives of this work were to analyse placental biometry and structure at term, growth of foals and yearlings, their metabolism and testicular maturation at one year of age. Twenty multiparous mares (M), aged over 6 y...
Barreto RSN, Romagnolli P, Mess AM, Rigoglio NN, Sasahara THC, Simões LS, Fratini P, Matias GSS, Jacob JCF, Gastal EL, Miglino MA.In horses, pregnancy is characterized by high levels of maternal estrogens that are produced largely by the interstitial tissue inside the gonads of the offspring, associated with a physiological gonadal hyperplasia, that is uncommon in other species. However, a detailed structural-functional understanding of the early stages of gonadal development and hyperplasia has remained elusive in horse pregnancy because of the lack of substantial data. The goal of this study was to describe the genital organs' development in 19 early horse embryos and fetuses (days 20-140 of gestation) of both sexes by...
Lindström H, Peer SM, Ing NH, Mannervik B.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 ...
Toishi Y, Tsunoda N, Nagata SI, Kirisawa R, Nagaoka K, Watanabe G, Yanagawa Y, Katagiri S, Taya K.Testosterone (T) concentration is a useful indicator of reproductive function in male animals. However, T concentration is not usually measured in veterinary clinics, partly due to the unavailability of reliable and rapid assays for animal samples. In this study, a rapid chemiluminescent enzyme immunoassay system (CLEIA system) that was developed for the measurement of T concentration in humans use was validated for stallion blood samples. First, serum T concentrations were measured using the CLEIA system and compared with those measured by a fluoroimmunoassay that has been validated for use i...
Fernandes CB, Loux SC, Scoggin KE, Squires EL, Troedsson MH, Esteller-Vico A, Ball BA.The cervix is a dynamic structure that undergoes dramatic changes during the estrous cycle, pregnancy and parturition. It is well established that hormonal changes, including estrogens, progestogens and prostaglandins, regulate the expression of key proteins involved in cervical function. The arachidonic acid cascade is important in the remodeling and relaxation of the cervix in the days preceding parturition. Despite the complexity of this mechanism, regulation of cervical function has received little study in the mare. Therefore, the objective of this study was to compare the expression of e...
Legacki EL, Corbin CJ, Ball BA, Scoggin KE, Stanley SD, Conley AJ.Steroidogenic enzymes in placentas shape steroid hormone profiles in the maternal circulation of each mammalian species. These include 3β-hydroxysteroid dehydrogenase/Δ5-4 isomerase (3βHSD) and 17α-hydroxylase/17,20-lyase cytochrome P450 (P450c17) crucial for progesterone and androgen synthesis, respectively, as well as aromatase cytochrome P450 (P450arom) that converts Δ4-androgens to estrogens. 5α-reductase is another important enzyme in equine placentas because 5α-dihydroprogesterone (DHP) sustains pregnancy in the absence of progesterone in the second half of equine pregnancy. DHP a...
Rota A, Sgorbini M, Panzani D, Bonelli F, Baragli P, Ille N, Gatta D, Sighieri C, Casini L, Maggiorelli MM, Aurich C, Camillo F.Reproductive management of male donkeys employed for artificial breeding has been poorly studied. The aim of this study was to evaluate the effect of housing system, with the animals grouped together in a paddock or kept in individual boxes, on sexual behaviour, cortisol and testosterone concentration and seminal characteristics of adult male donkeys. The study included four Amiata donkey jacks (stallions) from which ejaculates, saliva and blood were collected during two distinct 3 weeks periods, one in the group and one in the box housing system. Time needed for semen collection was shorter ...
Akhtar RW, Shah SAH, Qureshi IZ.This study was conducted to determine the response of serum testosterone (T) in male equines (stallions, donkeys and mules) after administering intravenous doses of kisspeptin-10 (KP-10), human chorionic gonadotropin (hCG) and luteinizing hormone (LH) and saline as a control. The animals were divided into four groups of three each: Group I, 3 ml of 0.95% saline; Group II, 50 μg KP-10; Group III, 2500 IU hCG and group IV, 400 μg LH. The administration of KP-10 and hCG to stallions resulted in a significant increase in serum T concentration at 240 min; whereas it was significantly higher a...
Pinto-Bravo P, Galvão A, Rebordão MR, Amaral A, Ramilo D, Silva E, Szóstek-Mioduchowska A, Alexandre-Pires G, Roberto da Costa R, Skarzynski DJ....The oviduct plays important roles in the early reproductive process. The aim of this study was to evaluate gene transcription and protein expression of progesterone receptor (PGR), estrogen receptors 1 (ESR1) and 2 (ESR2); oxytocin receptor (OXTR); prostaglandin F2α synthase (AKR1C3), and prostaglandin E2 synthase (Ptges) in mare oviduct in different estrous cycle stages. Estradiol (E), progesterone (P), oxytocin (OXT), and tumor necrosis factor α (TNF) effect on in vitro PGE and prostaglandin F2α (PGF) secretion by equine oviduct explants or by oviductal epithelial cells (OECs) were also ...
Shin HD, Suh JH, Kim J, Cho HD, Lee SD, Han KS, Wang Y, Han SB.A high throughput method for simultaneous screening of anabolic steroids and their metabolites (4-esterendione, trenbolone, boldenone, oxandrolone, nandrolone, methandrostenolone, testosterone, 1-androstendione, ethisterone, normethandrolone, methyltestosterone, 16β-Hydroxystanozolol, epitestosterone, bolasterone, norethandrolone, danazol, stanozolol and androstadienone) in equine urine by online turbulent flow extraction coupled with liquid chromatography-tandem mass spectrometry was developed. The use of turbulent flow chromatography could simplify pretreatment of horse urine, which has com...
Mendoza FJ, Serrano-Rodriguez JM, Buzon-Cuevas A, Perez-Ecija A.Alternatives to surgical castration are necessary for controlling the sexual behaviour of stallions with breeding potential in training and competition. Flutamide is a potent selective non-steroidal androgen receptor competitive antagonist that has been used in human beings as an anti-androgenic drug. In this study, the pharmacokinetics and bioavailability of flutamide and its main active metabolite, 2-hydroflutamide, were determined in seven healthy mature stallions. Single doses of flutamide (1mg/kg intravenously, 1mg/kg orally in fasted horses, 5mg/kg orally in fasted horses and 5mg/kg oral...
Wong JKY, Leung DKK, Curl P, Schiff PJ, Lam KKH, Wan TSM.The detection of boldenone, nandrolone, 5(10)-estrene-3β,17α-diol, and 4-estrene-3,17-dione in a urine sample collected from a gelding having been treated with testosterone (500 mg 'Testosterone Suspension 100', single dose, injected intramuscularly) in 2009 led the authors' laboratory to suspect that these 'testicular' steroids could be minor metabolites of testosterone in geldings. Administration trials on six castrated horses with Testosterone Suspension 100 confirmed that low levels of boldenone, nandrolone, 5(10)-estrene-3β,17α-diol, and 4-estrene-3,17-dione could indeed be detected ...
Schmidt K, Deichsel K, de Oliveira RA, Aurich J, Ille N, Aurich C.We hypothesized that housing of stallions in a thermoneutral temperature zone during autumn and winter does not only influence metabolism and hair shedding but also improves the characteristics of raw and processed semen. Fertile Shetland pony stallions were followed from October to June. This time coincided with the seasons autumn, winter and spring. Ponies were kept in outside paddocks (group CON, n = 8) or in indoor stables (group ST, n = 8) from October to March when ST stallions returned to outdoor paddocks, but ponies remained in the same groups. The rectal temperature was measured o...
Kwok KY, Choi TLS, Kwok WH, Wong JKY, Wan TSM.Anabolic and androgenic steroids (AASs) are a class of prohibited substances banned in horseracing at all times. The common approach for controlling the misuse of AASs in equine sports is by detecting the presence of AASs and/or their metabolites in urine and blood samples using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS). This approach, however, often falls short as the duration of effect for many AASs are longer than their detection time in both urine and blood. As a result, there is a high risk that such AASs could escape detection in the...
Vimercati S, Büchi M, Zielinski J, Peduto N, Mevissen M.Cytochrome P450 enzymes (CYPs) are responsible for the phase I metabolism of drugs, xenobiotics and endogenous substances. Knowledge of single CYPs and their substrates is important for drug metabolism, helps to predict adverse effects and may prevent reduced drug efficacy in polypharmacy. In this study, three equine isoenzymes of the 3A subfamily, the equine flavoprotein NADPH-P450 oxidoreductase (POR), and the cytochrome b5 (CYB5) were cloned, sequenced and heterologously expressed in a baculovirus expression system. Testosterone, the standard compound for characterization of the human CYP3A...
Waddington B, Penitente-Filho JM, Neves J, Pinho RO, Chaya AY, Maitan PP, Silveira CO, Neves MG, Guimarães S, de Carvalho GR, Guimarães JD.This study was conducted to characterize the daily profile of testosterone secretion and its mean concentrations in the four seasons as well as to evaluate the semen characteristics and testicular biometry of Mangalarga Marchador stallions throughout the year in a tropical region. Three stallions were submitted to semen collections and evaluation of testicular biometry every 14 days along a year. Blood samples were collected once at the middle of each season, in a 20-min interval during 24 hr in order to evaluate the testosterone secretion profiles among seasons. Testosterone concentrations ...
D'Souza-Anjo M, Christensen BW, Brabender K, Zimmermann W, Kass PH, Schwarzenberger F.The aim of this study was to determine whether concentrations of reproductive steroid hormone metabolites significantly differed between harem stallions and bachelor stallions in the free ranging group of Przewalski's horses (Equus ferus przewalskii) at the Hortobágy National Park in Hungary. Throughout the study, fecal samples were collected from 21 harem stallions and 15 bachelor stallions and analyzed for immunoreactive estrogen and androgen metabolites. Harem stallions demonstrated significantly higher concentrations of estrogen (P < 0.001) and epi-androsterone (P < 0.001), ...
Viljanto M, Scarth J, Hincks P, Hillyer L, Cawley A, Suann C, Noble G, Walker CJ, Kicman AT, Parkin MC.Detection of testosterone and/or its pro-drugs in the gelding is currently regulated by the application of an international threshold for urinary testosterone of 20 ng/mL. The use of steroid ratios may provide a useful supplementary approach to aid in differentiating between the administration of these steroids and unusual physiological conditions that may result in atypically high testosterone concentrations. In the current study, an ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method was developed to quantify testosterone (T) and epitestosterone (E). ...
Genangeli M, Caprioli G, Cortese M, Laus F, Matteucci M, Petrelli R, Ricciutelli M, Sagratini G, Sartori S, Vittori S.A new, fast and simple analytical method that is able to identify and quantify simultaneously 17 steroid hormones and metabolites (pregnenolone, 17-OH-pregnenolone, progesterone, 17-OH-progesterone, androsterone, androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate, testosterone, cortisol, corticosterone, aldosterone, 11-deoxycortisol, 11-deoxycorticosterone, dihydrotestosterone, estrone and estradiol) has been developed in equine serum using the ultra-high-performance liquid chromatography-tandem mass spectrometry technique. A total of 400 µl of sample was deproteinized ...
Burger D, Meuwly C, Marti E, Sieme H, Oberthür M, Janda J, Meinecke-Tillmann S, Wedekind C.Genes of the major histocompatibility complex (MHC) have been shown to influence communication in many vertebrates, possibly with context-specific MHC-correlated reactions. Here we test for MHC-linked female preferences in the polygynous horse (Equus caballus) by repeatedly exposing 19 mares to a group of seven sexually experienced stallions. Each mare was tested four times during two consecutive reproductive cycles, twice during estrus and twice during diestrus. Male plasma testosterone concentrations were determined from weekly blood samples, and equine leukocyte antigen (ELA) class I and II...
Corbin CJ, Legacki EL, Ball BA, Scoggin KE, Stanley SD, Conley AJ.The 5α-reductase enzymes play an important role during male sexual differentiation, and in pregnant females, especially equine species where maintenance relies on 5α-reduced progesterone, 5α-dihydroprogesterone (DHP). Epididymis expresses 5α-reductases but was not studied elaborately in horses. Epididymis from younger and older postpubertal stallions was divided into caput, corpus and cauda and examined for 5α-reductase activity and expression of type 1 and 2 isoforms by quantitative real-time polymerase chain reaction (qPCR). Metabolism of progesterone and testosterone to DHP and dihydro...
Pereira GR, Lorenzo PL, Carneiro GF, Ball BA, Bilodeau-Goeseels S, Kastelic J, Pegoraro LM, Pimentel CA, Esteller-Vico A, Illera JC, Granado GS....The objectives of this study were to evaluate the effects of equine growth hormone (eGH) on nuclear and cytoplasmic maturation of equine oocytes in vitro, steroid production by cumulus cells, and expression and subcellular localization of eGH-receptors (eGH-R) on equine ovarian follicles. Cumulus-oocyte complexes (COCs) were recovered by aspirating follicles <30 mm in diameter from abattoir-derived ovaries. The COCs were morphologically evaluated and randomly allocated to be cultured in either a control maturation medium or supplemented with 400 ng/mL eGH, for 30 h at 38.5°C in air with 5%...
Burger D, Dolivo G, Wedekind C.Sperm competition theory predicts semen characteristics to be affected by the social environment. We used the polygamous horse (Equus caballus) to experimentally study within-subject plasticity in response to different social environments. Stallions were sequentially exposed, over a period of 8 weeks each, to other stallions and then singly to mares, or vice versa (in adjacent boxes separated by grills). Ejaculates were collected to determine semen characteristics. Highest sperm numbers were found in stallions that were first exposed to other stallions and then to mares, while lowest sperm num...
Schmidt K, Deichsel K, de Oliveira RA, Aurich J, Ille N, Aurich C.We hypothesized that housing of stallions in a thermoneutral temperature zone during autumn and winter does not only influence metabolism and hair shedding but also improves the characteristics of raw and processed semen. Fertile Shetland pony stallions were followed from October to June. This time coincided with the seasons autumn, winter and spring. Ponies were kept in outside paddocks (group CON, n = 8) or in indoor stables (group ST, n = 8) from October to March when ST stallions returned to outdoor paddocks, but ponies remained in the same groups. The rectal temperature was measured o...
Anielski P.Doping control of anabolic substances is normally carried out with urine samples taken from athletes and horses. Investigation of alternative specimens, e.g. hair samples, is restricted to special cases, but can also be worthwhile, in addition to urine analysis. Moreover, hair material is preferred in cases of limited availability or complicated collection of urine samples, e.g. from horses. In this work, possible ways of interpretation of analytical results in hair samples are discussed and illustrated by practical experiences. The results demonstrate the applicability of hair analysis to det...
Conley AJ, Ball BA.Historically, studies on the endocrinology of pregnancy and parturition in horses have made major contributions of relevance to mammals in general. Recent use of liquid chromatography mass spectrometry, measuring multiple steroid hormones simultaneously in blood, foetal and placental tissues throughout normal gestation, and in mares with experimentally induced placentitis, has advanced our current understanding of many of the unusual strategies seen during gestation and at foaling. This includes the stimulation of luteal steroidogeneisis by equine chorionic gonadotropin (eCG) from the endometr...
Guan F, Uboh CE, Soma LR, Luo Y, Rudy J, Tobin T.Anabolic androgenic steroids are related to the male sex hormones and are abused in equine sports. In an effort to deter the abuse of anabolic steroids, a sensitive LC-MS/MS method was developed for detection, quantification and confirmation of eight major anabolic steroids (testosterone, normethandrolone, nandrolone, boldenone, methandrostenolone, tetrahydrogestrinone (THG), trenbolone, and stanozolol) in equine plasma. Formation of solvent adduct ions of the analytes was observed under electrospray ionization (ESI) conditions, and desolvation of the solvent adduct ions by source collision-in...
Burger D, Dolivo G, Marti E, Sieme H, Wedekind C.Odours of vertebrates often contain information about the major histocompatibility complex (MHC), and are used in kin recognition, mate choice or female investment in pregnancy. It is, however, still unclear whether MHC-linked signals can also affect male reproductive strategies. We used horses (Equus caballus) to study this question under experimental conditions. Twelve stallions were individually exposed either to an unfamiliar MHC-similar mare and then to an unfamiliar MHC-dissimilar mare, or vice versa. Each exposure lasted over a period of four weeks. Peripheral blood testosterone levels ...
Pashen RL, Allen WR.The effects of fetal gonadectomy on steroid production and the maintenance of pregnancy in the mare were studied. Removal of the fetal gonads resulted in an immediate fall in maternal plasma concentrations of conjugated and unconjugated oestrogens whereas progestagen levels remained unchanged. Hormone profiles in mares carrying sham-operated fetuses remained similar to those in unoperated control mares. Plasma levels of 13,14-dihydro-15-oxo-PGF-2 alpha (PGFM) were much lower, and uterine contractions weaker, during labour in mares carrying gonadectomized foals than in control mares. Pregnancy ...
Petrucci L, Maranesi M, Verini Supplizi A, Dall'Aglio C, Mandara MT, Quassinti L, Bramucci M, Miano A, Gobbetti A, Catone G, Boiti C, Zerani M.The objectives of this study were to evaluate in horse testes the expression of kisspeptin (KiSS) and GnRH1 neuropeptides and their cognate receptors, KiSS1R and GnRH1R, as well as their action on testosterone, GnRH1, prostaglandin F2α (PGF2α), and PGE2 synthesis and cyclooxygenase 1 (COX1) and COX2 activity by Leydig cells in vitro. Testes were obtained from 9 sexually mature horses by surgical castration. Immunohistochemistry, evidenced the presence of KiSS, KiSS1R, GnRH, and GnRH1R in Leydig cells, whereas germinal and Sertoli cells were positive only for GnRH1. Transcripts for both neur...
Rota A, Sgorbini M, Panzani D, Bonelli F, Baragli P, Ille N, Gatta D, Sighieri C, Casini L, Maggiorelli MM, Aurich C, Camillo F.Reproductive management of male donkeys employed for artificial breeding has been poorly studied. The aim of this study was to evaluate the effect of housing system, with the animals grouped together in a paddock or kept in individual boxes, on sexual behaviour, cortisol and testosterone concentration and seminal characteristics of adult male donkeys. The study included four Amiata donkey jacks (stallions) from which ejaculates, saliva and blood were collected during two distinct 3 weeks periods, one in the group and one in the box housing system. Time needed for semen collection was shorter ...
Lemazurier E, Moslemi S, Sourdaine P, Desjardins I, Plainfosse B, Seralini GE.The steroid content of semen from a total of 11 mature fertile stallions was studied during two breeding seasons and one winter. The levels of free and conjugated substrates (testosterone and androstenedione), and products (estradiol and estrone), of aromatase were measured by radioimmunoassay with a validated method. The results were seasonally and monthly highly variable with characteristic peaks. The concentrations of free and conjugated estrogens were always higher in the gel-free ejaculate than in the gel except in one subfertile stallion used as comparison. Furthermore, the steroid produ...
Naden J, Amann RP, Squires EL.Puberty was studied using 15 colts of Quarter Horse phenotype. Total scrotal width was measured every 8 weeks from 48 to 96 weeks. Blood samples were taken from 8 colts at 8, 16 and 24 weeks and then every 4 weeks until 100 weeks to measure changes in LH, FSH and testosterone concentrations. Seminal collections were attempted monthly from 48 to 64 weeks and every 2 weeks thereafter until puberty resumed every 3rd day from 96 weeks for 15 ejaculates. For all collections, times to erection, mount and ejaculation and seminal characteristics were recorded. Age at puberty was defined as the first e...
Satué K, Marcilla M, Medica P, Ferlazzo A, Fazio E.Androgens modulate maternal ovarian activity, embryo implantation and correct placental development. The objective of this study was to establish reference values for testosterone (T), androstenedione (A4) and dehydroepiandrosterone (DHEA) concentrations in pregnant mares. A total of 30 healthy Spanish Purebred mares with an age range of 9.33 ± 3.31 years, were studied during the 11 months of gestation. T, A4 and DHEA concentrations were determined using EIA validated specifically for equines. T increased in the 2nd and 3rd month (P < 0.05), showing a plateau between the 4th and 6th m...
Legacki EL, Scholtz EL, Ball BA, Esteller-Vico A, Stanley SD, Conley AJ.Few studies have provided a longitudinal analysis of systemic concentrations of conjugated oestrogens (and androgens) throughout pregnancy in mares, and those only using immunoassay. The use of liquid chromatography tandem mass spectrometry (LC-MS/MS) will provide more accurate concentrations of circulating conjugated steroids. Objective: To characterise circulating concentrations of individual conjugated steroids throughout equine gestation by using LC-MS/MS. Methods: Longitudinal study and comparison of pregnant mares treated with vehicle or letrozole in late gestation. Methods: Sulphated oe...
Haneda S, Dini P, Esteller-Vico A, Scoggin KE, Squires EL, Troedsson MH, Daels P, Nambo Y, Ball BA.A sufficient vascular network within the feto-maternal interface is necessary for placental function. Several pregnancy abnormalities have been associated with abnormal vascular formations in the placenta. We hypothesized that growth and expansion of the placental vascular network in the equine () placenta is regulated by estrogens (estrogen family hormones), a hormone with a high circulating concentration during equine gestation. Administration of letrozole, a potent and specific inhibitor of aromatase, during the first trimester (D30 to D118), decreased circulatory estrone sulfate concentrat...
Pearl CA, Roser JF.Lactoferrin is one of the most abundant proteins secreted by the stallion epididymis, but its cellular localization and regulation remain unknown. This study was designed to address the following objectives: (1) identify the epididymal cell types producing lactoferrin in pre-pubertal, peri-pubertal and post-pubertal animals; (2) demonstrate that lactoferrin binds to stallion sperm; and (3) determine if testosterone and estradiol regulate lactoferrin secretion in vitro. Using an immunohistochemical method, lactoferrin was localized in the cytoplasm of principal cells in the corpus and cauda of ...
Squires EL, Todter GE, Berndtson WE, Pickett BW.Thirty-two stallions were used to determine the effect of anabolic steroids on reproductive function. Stallions were assigned to one of the four treatments: 1) .23 ml sesame oil/kg of body weight (BW; control, C); 2) 4.4 mg boldenone undecylenate/kg BW (4E); 3) 1.1 mg boldenone undecylenate/kg BW (1E) and 4) 1.1 mg nandrolone decanoate/kg BW (D). Injections were given at 3-wk intervals for 15 wk. Semen was collected every other day for 3 wk before the first injection and at the same frequency during d 85 through 105 (d 0 = day of first injection). Libido was assessed on the basis of reaction t...
Genangeli M, Caprioli G, Cortese M, Laus F, Matteucci M, Petrelli R, Ricciutelli M, Sagratini G, Sartori S, Vittori S.A new, fast and simple analytical method that is able to identify and quantify simultaneously 17 steroid hormones and metabolites (pregnenolone, 17-OH-pregnenolone, progesterone, 17-OH-progesterone, androsterone, androstenedione, dehydroepiandrosterone, dehydroepiandrosterone sulfate, testosterone, cortisol, corticosterone, aldosterone, 11-deoxycortisol, 11-deoxycorticosterone, dihydrotestosterone, estrone and estradiol) has been developed in equine serum using the ultra-high-performance liquid chromatography-tandem mass spectrometry technique. A total of 400 µl of sample was deproteinized ...
Canisso IF, Ball BA, Esteller-Vico A, Williams NM, Squires EL, Troedsson MH.While advanced stages of ascending placentitis can be diagnosed by transrectal ultrasonography and clinical signs, early stages can be missed. Thus, additional tools could enhance assessment of placental health. Objective: To characterise peripheral dehydroepiandrosterone sulphate (DHEA-S) and testosterone concentrations in mares carrying normal pregnancies (Study 1) and compare plasma concentrations of DHEA-S, testosterone, oestradiol 17-β (oestradiol) and oestrone sulphate (OES) in mares with or without placentitis (Study 2). Methods: Longitudinal cohort study of healthy mares (Study 1) and...
Bilińska B, Wiszniewska B, Kosiniak-Kamysz K, Kotula-Balak M, Gancarczyk M, Hejmej A, Sadowska J, Marchlewicz M, Kolasa A, Wenda-Rózewicka L.The purpose of this article was to summarize our results on the role of androgens and estrogens in human, rodent and equine testes and epididymides, in both, physiological and patological conditions, obtained in the space of the Solicited Project (084/PO6/2002) financially supported by the State Committee for Scientific Research during the last three years. Testosterone produced by Leydig cells of the testes is clearly the major androgen in the circulation of men and adult males of most mammalian species. However, androgen metabolites make up a significant fraction of total circulating steroid...
Roser JF, Hughes JP.Seasonal effects on hormonal and seminal parameters in subfertile stallions have not been well documented and could provide information that is needed to understand the underlying endocrine mechanisms associated with testicular dysfunction. Such information may be useful in developing diagnostic tools to identify those stallions who are candidates for treatment. This investigation characterizes and compares the effects of season on endocrine function and seminal quality in fertile and subfertile stallions. Eight fertile and six subfertile stallions between the ages of 5 and 18 years were injec...
Neto AC, Ball BA, Browne P, Conley AJ.Elevated blood testosterone concentrations, often accompanied by male-typical behaviors, is a common signalment of mares with granulosa-theca cell tumors (GCTCs), but no definitive information exists regarding the cellular differentiation of tumors associated with androgen secretion. This study was conducted to localize and thereby define the cellular expression of 17alpha-hydroxylase/17,20-lyase cytochrome P450 (P450c17), the enzyme most directly responsible for androgen synthesis, in 30 GTCTs and control tissues (gonads and adrenal glands) using immuno-histochemistry (IHC). Immuno-reactivity...
Ellenberger C, Bartmann CP, Hoppen HO, Kratzsch J, Aupperle H, Klug E, Schoon D, Schoon HA.Benign (n=33) and malignant metastasizing (n=1) granulosa cell tumours (GCTs) from 34 mares aged 3-21 years, and normal (control) ovaries from nine mares aged 3-10 years, were examined histologically and immunohistochemically (for inhibin alpha, glutathione S-transferase alpha [GSTalpha], c-erbB-2 oncoprotein [cerb], cytokeratin, vimentin, desmin and alpha-actin), the results being related where appropriate to clinical signs and endocrinological data. Availability permitting, serum samples from GCT-affected mares before and several weeks after ovariectomy were examined for the following hormon...
Brown KA, Boerboom D, Bouchard N, Doré M, Lussier JG, Sirois J.Aldo-keto reductases (AKRs) are multifunctional enzymes capable of acting on a wide variety of substrates, including sex steroids. AKRs having 20alpha-hydroxysteroid dehydrogenase (20alpha-HSD) activity can reduce progesterone to 20alpha-hydroxy-4-pregnen-3-one (20alpha-DHP), a metabolite with lower affinity for the progesterone receptor. The objective of this study was to investigate the regulation of equine AKR1C23 during human chorionic gonadotropin (hCG)-induced ovulation/luteinization. The equine AKR1C23 cDNA was cloned and shown to encode a 322 amino acid protein that is conserved (71-81...
Setchell BP, Cox JE.In 3 testes of 2 adult Pony stallions under halothane anaesthesia, catheters were inserted into a vein and a lymphatic vessel in the spermatic cord and into a vein on the surface of the testis. Lymph and venous blood were collected from the catheters in the cord and p-aminohippurate (2% w/v, 0 . 1 ml/min) was infused into the vein on the testis to determine blood flow by dilution. After 1 h, 6000 i.u. hCG was injected i.v. and collections continued for 45 min. The testes weighed 126-176 g. Lymph flow was 20-150 microliter/min before hCG and 100-270 microliter/min after hCG; the range of blood ...
Hamed MA, Amin YA, Mohamed RH, El-Adl M, Bazeed SM, Elnegiry AA, Shawki HH, Al-Lethie AA.Chemical castration of male animals is an alternative to surgical castration for inducing azoospermia, consequent sterility. Intra-testicular injection of zinc gluconate has been used for chemical castration in several animal species. However, its application to equine species, such as donkeys, has yet to be reported. This study aimed to evaluate the use of zinc gluconate for the chemical castration of male donkeys and to compare its effectiveness relative to routine surgical castration. For this purpose, investigations of serum testosterone and anti-Müllerian hormone levels, testicular ultra...
Brown-Douglas CG, Firth EC, Parkinson TJ, Fennessy PF.There is little information on age, weight and time of year of puberty in Thoroughbred horses, and the interpretation of such data is difficult due to the wide variety of descriptions of the onset of puberty. Objective: To examine the age, bodyweight and date of onset of puberty in Thoroughbreds born in spring and autumn. Methods: Bodyweight data and blood samples were collected in 59 pasture-raised Thoroughbred horses. Five autumn-born and 18 spring-born colts and 3 autumn-born and 33 spring-born fillies were examined from birth to age 13 and 17 months. A testosterone concentration >2 s.d. ab...
Stout TA.Situations in which suppression or stimulation of reproductive activity in stallions has been attempted, or is desired, include resolution of the equine arteritis virus 'shedding' state, induction of testicular descent in inguinal cryptorchids, and the improvement of sperm production capacity and/or semen quality in sub-fertile stallions. However, the most common reason for wanting to modulate reproductive activity in a stallion is to alter the expression of sexual behaviour. In the case of intact stallions used for competitive or recreational purposes, the overt expression of sexual or aggres...
Medill SA, Janz DM, McLoughlin PD.Steroid-hormone concentrations from non-invasively obtained biomarkers, like hair, can provide a representation of circulating hormones diffused over relatively long time periods (e.g., weeks or months). The hormone cortisol is often associated with physiological or even psychological stress, while testosterone is strongly associated with male development and reproductive success. Increasingly, studies are using hormone levels derived from hair to make inferences among both domestic animals and wildlife. For horses, all previous hair hormone analysis has been done on companion or working anima...
