Domestic animal endocrinology.
Publisher:
Domendo, Inc.,. Stoneham, Ma : Elsevier
Frequency: Quarterly, 2014-
Country: United States
Language: English
Start Year:1984 -
ISSN:
0739-7240 (Print)
1879-0054 (Electronic)
0739-7240 (Linking)
1879-0054 (Electronic)
0739-7240 (Linking)
Impact Factor
2.1
2022
| NLM ID: | 8505191 |
| (DNLM): | SR0052014(s) |
| (OCoLC): | 09834328 |
| Coden: | DANEEE |
| LCCN: | sn 83008664 |
| Classification: | W1 DO656 |
Effects of hyperinsulinemia on glucose and lipid transporter expression in insulin-sensitive horses. Plasma insulin concentrations are elevated (hyperinsulinemia) in horses with obesity-associated insulin resistance. In other species, insulin resistance is partly due to reduced levels of insulin receptor and the insulin-sensitive glucose transporter, and, in vitro, chronic hyperinsulinemic conditions reduce the expression of these proteins. Consumption of grain-based concentrate feeds results in postprandial hyperinsulinemia in horses, and adaptation to these diets is associated with insulin resistance. As such, it is possible that the repeated, chronic postprandial hyperinsulinemia associate...
Nitric oxide stimulates progesterone and prostaglandin E2 secretion as well as angiogenic activity in the equine corpus luteum. Cytokines and nitric oxide (NO) are potential mediators of luteal development and maintenance, angiogenesis, and blood flow. The aim of this study was to evaluate (i) the localization and protein expression of endothelial and inducible nitric oxide synthases (eNOS and iNOS) in equine corpora lutea (CL) throughout the luteal phase and (ii) the effect of a nitric oxide donor (spermine NONOate, NONOate) on the production of progesterone (P4) and prostaglandin (PG) E(2) and factor(s) that stimulate endothelial cell proliferation using equine luteal explants. Luteal tissue was classified as corpora...
Cortisol release, heart rate, and heart rate variability in transport-naive horses during repeated road transport. Domestic animals are often repeatedly exposed to the same anthropogenic stressors. Based on cortisol secretion and heart rate, it has been demonstrated that transport is stressful for horses, but so far, changes in this stress response with repeated road transport have not been reported. We determined salivary cortisol concentrations, fecal cortisol metabolites, cardiac beat-to-beat (RR) interval, and heart rate variability (HRV) in transport-naive horses (N = 8) transported 4 times over a standardized course of 200 km. Immunoreactive salivary cortisol concentrations always increased in respon...
Platelet-derived growth factor acts via both the Rho-kinase and p38 signaling enzymes to stimulate contraction in an in vitro model of equine wound healing. Horses are more prone to complications in the wound healing process than other species, and problems such as chronic inflammation, delayed epithelialization, poor wound contraction, and exuberant granulation tissue are commonly seen, particularly in wounds on the distal limbs. In comparison, wounds of the oral mucosa heal rapidly in a scarless fashion with a high degree of wound contraction. The effect of platelet-derived growth factor BB (PDGF), insulin-like growth factor (IGF)-1, and transforming growth factor beta1 (TGFbeta1) on the contraction of a fibroblast-populated collagen matrix (FPC...
Changes in cortisol release and heart rate variability in sport horses during long-distance road transport. It is widely accepted that transport is stressful for horses, but only a few studies are available involving horses that are transported regularly and are accustomed to transport. We determined salivary cortisol immunoreactivity (IR), fecal cortisol metabolites, beat-to-beat (RR) interval, and heart rate variability (HRV) in transport-experienced horses (N=7) in response to a 2-d outbound road transport over 1370 km and 2-d return transport 8 d later. Salivary cortisol IR was low until 60 min before transport but had increased (P<0.05) 30 min before loading. Transport caused a further marked i...
Insulin sensitivity and glucose dynamics during pre-weaning foal development and in response to maternal diet composition. Nutritional management of animals during pregnancy can affect glucose and insulin dynamics in the resulting offspring through influences on fetal development. Additionally, high starch feeding in mature horses is associated with reduced insulin sensitivity and an increased risk for diseases such as obesity and laminitis. However, no study has yet evaluated the effect of feeding a high starch diet to pregnant mares on glucose and insulin dynamics in their offspring. Twenty late-gestation mares maintained on pasture were provided two-thirds of digestible energy requirements from isocaloric, ison...
Interleukin-1 receptor antagonist expression in the equine endometrium during the peri-implantation period. To identify factors involved in the establishment of pregnancy in the mare, endometrium was collected from day 13 (day 0=day of ovulation) cyclic and day 13, 19, and 25 pregnant animals. From initial cDNA subtraction studies, interleukin-1 receptor antagonist (IL-1RN) mRNA was found as a candidate molecule expressed uniquely in the pregnant endometrium. Expression of IL-1RN mRNA was markedly increased in day 19 and 25 gravid endometrium. In situ hybridization analysis revealed that IL-1RN mRNA was localized to the glandular epithelium. Interleukin-1 receptor antagonist (IL-1RN) protein was fou...
Rapid calcitonin response to experimental hypercalcemia in healthy horses. Calcium has important physiological functions, and disorders of calcium homeostasis are frequent in horses. We have made important progress understanding equine calcium homeostasis; however, limited information on equine calcitonin (CT) is available, in part because of the lack of validated CT assays. To determine the CT response to high ionized calcium (Ca(2+)) concentrations in healthy horses, we induced hypercalcemia in 10 healthy horses using a calcium gluconate 23% solution (5mg/kg; 120 mL/500 kg horse) infused over 4 min. Four horses were infused with 120 mL of 0.9% NaCl and used as cont...
The efficacy of a single chain recombinant equine luteinizing hormone (reLH) in mares: induction of ovulation, hormone profiles, and inter-ovulatory intervals. The objectives of this study were to determine the efficacy of recombinant equine luteinizing hormone (reLH) in shortening the time to ovulation in cycling mares and to determine the effects of treatment on endogenous hormones and inter-ovulatory intervals. In study 1, mares of light horse breeds (3-20 years) were treated with either a vehicle, various doses of reLH, or human chorionic gonadotropin (hCG). Cycling mares were examined by palpation and ultrasound per rectum daily or every 12h from the time of treatment to ovulation. In studies 2 and 3, jugular blood samples were collected daily o...
Seasonal and pulsatile dynamics of thyrotropin and leptin in mares maintained under a constant energy balance. The objective of this study was to determine if seasonal and/or pulsatile variations occur in plasma concentrations of thyrotropin (TSH) and leptin in mares while maintaining a constant energy balance. Blood samples were collected every 20 min during a 24h period in winter and again in summer from six Quarter Horse type mares. Plasma concentrations of TSH, leptin, and T(4) were determined by radioimmunoassay. No differences were observed in body weight between winter (388.1+/-12.5 kg) and summer (406.2+/-12.5 kg; P=0.11). Plasma concentrations of TSH were greater in the summer (2.80+/-0.07 ng/...
Effect of prostaglandin F2alpha on ovarian, adrenal, and pituitary hormones and on luteal blood flow in mares. The effect of a single injection of prostaglandin F2alpha (PGF) during mid-diestrus on systemic concentrations of progesterone, LH, FSH, estradiol, and cortisol and on blood flow to the corpus luteum was studied in 10 controls and 10 PGF-treated mares. Blood flow was assessed by estimating the percentage of corpus luteum with color-Doppler signals of blood flow during real-time scanning of the entire structure and by the diameter of the vascular pedicle near its attachment to the ovary. Treatment was done 8 days after ovulation and 0 h was immediately before the treatment. Examinations and col...
Endometrial nitric oxide production and nitric oxide synthases in the equine endometrium: Relationship with microvascular density during the estrous cycle. Nitric oxide (NO) plays an important role in angiogenesis and in the regulation of the blood flow. This study was carried out to investigate (i) the effects of endogenous estrogens and progestins and exogenous progesterone (P(4)) (5 ng/ml or 1 microg/ml) or estradiol 17beta (E(2)beta) (50 pg/ml or 1 microg/ml) on in vitro endometrial NO synthesis; (ii) the presence of different isoforms of NO synthase; (iii) and their relationship to microvascular density in the equine endometrium during the estrous cycle. NOS expression was also evaluated in the myometrium. Expression of endothelial and induc...
Leptin secretion in horses: effects of dexamethasone, gender, and testosterone. Five experiments were performed to evaluate the effects of dexamethasone (DEX), gender, and testosterone on plasma leptin concentrations in horses. In experiment 1, plasma leptin, insulin, glucose, and IGF-1 concentrations were increased (P < 0.01) in stallions following five daily injections of DEX (125 microg/kg BW). In experiment 2, leptin concentrations increased (P < 0.01) in mares, geldings, and stallions following a single injection of DEX, and the response was greater (P < 0.01) in mares and geldings than in stallions. The gender effect was confounded by differences in body co...
Production and characterization of recombinant equine prorelaxin. Relaxin is a peptide hormone produced by a wide variety of mammals. In the horse, the placenta is the major source of relaxin. Since pure equine relaxin is difficult to obtain to study its role in the pregnant mare, the objectives of this study were to produce recombinant equine prorelaxin and characterize its immunological and biological activity. First, an equine relaxin gene cassette was transfected into immortalized bovine mammary epithelial (MAC-T) cells. Second, immunological activity of media conditioned by transfected MAC-T cells was tested by Western blotting and quantified using a ho...
Expression of inhibins, activins, insulin-like growth factor-I and steroidogenic enzymes in the equine placenta. In this study, the expression patterns of inhibins, activins, insulin-like growth factor-I (IGF-I) and steroidogenic enzymes in equine placentae recovered during the latter two-thirds of gestation were examined. Concentrations of inhibin A and inhibin pro-alphaC in endometrial and fetal placental tissue homogenates were very low during the period examined, whereas these tissues contained high concentrations of activin A. In both maternal endometrial and fetal placental tissues, activin A levels decreased as pregnancy progressed. Expression of inhibin alpha-subunit was not observed in the place...
Microvascularization and angiogenic activity of equine corpora lutea throughout the estrous cycle. Corpus luteum growth and endocrine function are closely dependent on the formation of new capillaries. The objectives of this study were to evaluate (i) tissue growth and microvascular development in the equine cyclic luteal structures; (ii) in vitro angiogenic activity of luteal tissues in response to luteotrophic (LH, PGE(2)) and luteolytic (PGF(2alpha)) hormones and (iii) to relate data to luteal endocrinological function. Our results show that microvascular density was increased in the early and mid luteal phase, followed by a fall in the late luteal phase and a further decrease in the cor...
Alpha-melanocyte stimulating hormone release in response to thyrotropin releasing hormone in healthy horses, horses with pituitary pars intermedia dysfunction and equine pars intermedia explants. Thyrotropin releasing hormone (TRH) stimulates an increase in plasma cortisol in horses with pars intermedia dysfunction (PPID, Cushing's disease). A similar phenomenon is observed in humans with Cushing's disease or Nelson's syndrome. The mechanism of the response in humans is not known, but an alteration in receptor expression, selectivity or responsiveness in abnormal corticotropes has been proposed. Horses with PPID, unlike humans, almost exclusively have adenomas of pars intermedia (PI) rather than pars distalis (PD) origin. Therefore, the mechanism responsible for the TRH response observ...
Expression of aromatase and oestrogen receptors in reproductive tissues of the stallion and a single cryptorchid visualised by means of immunohistochemistry. Androgen metabolism may proceed to amplify the action of testosterone by its aromatisation to oestradiol. Recently, a growing body of evidence suggests a role of oestrogens in the male reproductive tract via their specific oestrogen receptors (ERs). In order to check whether androgens are converted to oestrogens in the testis, epididymis and prostate of the stallion, the expression of aromatase was visualised by means of immunohistochemistry. Moreover, to show the cellular targets for oestrogens the presence of oestrogen receptor alpha (ERalpha) and oestrogen receptor beta (ERbeta) was demonst...
Dopamine receptors in equine ovarian tissues. Dopamine (DA) agonist and antagonist treatments can affect ovarian reproductive events in the mare. To support our theory that DA produces these effects by acting directly on the ovary, we analyzed equine ovarian tissues for the presence of dopamine receptor-1 (D1r) and dopamine receptor-2 (D2r) mRNA by reverse transcription polymerase chain reaction (RT-PCR) and D1r and D2r proteins by Western blot and immunohistochemistry (IHC). RT-PCR was performed on RNA isolated from ovarian cortex, medulla, granulosa/theca or corpus luteum (CL) tissues and from pituitary (D2r control) and renal artery (D...
Follicular fluid concentrations of free insulin-like growth factor (IGF)-I during follicular development in mares. The objective of the present study was to evaluate changes in concentrations of free insulin-like growth factor (IGF)-I in follicular fluid (FFL) during follicle development in the mare. Mares (n = 14) were classified as either in the follicular phase (n = 8) or luteal phase (n = 6). Follicles (n = 92) were categorized as small (6-15 mm; n = 54), medium (16-25 mm; n = 23) or large (>25 mm; n = 15) and FFL was collected. Free IGF-I levels in FFL in large follicles of follicular phase mares were greater (P < 0.05) than in large follicles of luteal phase mares and small or medium follicles ...
Seasonal reproduction in the mare: possible role of plasma leptin, body weight and immune status. The primary objective of this study was to evaluate the possible role of leptin, body weight and immune status on reproductive activity throughout the transition period from cyclicity to seasonal anestrus, during anestrus and resumption of ovarian activity in Lusitano mares. Mares in good body condition were monthly monitored throughout 2 years (10 mares in each year) for evaluation of their reproductive status by sequential ultrasonography and plasma progesterone determinations. On the second year, all mares were weighed. Progesterone and leptin were assayed by radioimmunoassay (RIA). Paramet...
Attempt to control the day of ovulation in cycling pony mares by associating a GnRH antagonist with hCG. With the objective of controlling the day of ovulation, 40 mares were assigned to a control or three treated groups: A3d, A4d, and A5d. The treated groups received antarelix (Teverelix 0.01 mg/kg, i.v., twice a day) for 3, 4, or 5 days from the day the dominant follicle (F1) reached 28 mm (=D0), and one injection of hCG (1600 IU, i.v.) on D1, D2, or D3, respectively. Control mares received one injection of hCG when F1 reached 35 mm. Plasma LH, FSH, progesterone, and total estrogens were assayed. In the A3d, A4d, and A5d groups, 9 (90%), 6 (60%), and 5 (50%) out of 10 mares, respectively, ovula...
Expression of messenger ribonucleic acid encoding for steroidogenic acute regulatory protein and enzymes, and luteinizing hormone receptor during the spring transitional season in equine follicles. The period of spring transition, from the anovulatory to the ovulatory season, is characterized in many mares by cyclical growth and regression of large dominant follicles. These follicles produce only low concentrations of estradiol and it is thought that acquisition of steroidogenic competence by large follicles during spring transition is prerequisite in stimulating LH prior to first ovulation. In situ hybridization was used to localize and quantify expression of factors that play a key role in follicular steroidogenesis: StAR, P450scc (CYP11A1), P450c17 (CYP17), P450arom (CYP19), and LH re...
Effects of lactation on metabolic and reproductive hormones in Lipizzaner mares. In this study, growth hormone (GH), insulin-like growth factor 1 (IGF-1), leptin, luteinising hormone (LH) and prolactin were analyzed in mares from late pregnancy throughout lactation (group 1, n=46) and in non-lactating mares (group 2, n=11). Plasma GH concentrations in group 1 mares during gestation and lactation were lower than in mares of group 2 (P<0.05). Highest IGF-1 levels were found in lactating mares in the week of foaling. IGF-1 concentrations decreased continuously thereafter. Plasma leptin concentrations decreased after foaling and, for 4 weeks, were lower in lactating than in...
Relationship between pharmacological induction of estrous and/or ovulation and twin pregnancy in the Thoroughbred mares. The aim of this study was to evaluate the possible relationship of pharmacological induction of estrous and/or ovulation with the occurrence of twin pregnancies in Thoroughbred mares. Out of 680 mares, 356 received one of the following treatments during the estrous cycle in which they became pregnant: injection of 0.5mg of cloprostenol at the ultrasonographic detection of a CL (n=86); injection of 5000 IU human chorionic gonadotropin (hCG) immediately before mating (n=221); injection of 0.5mg of cloprostenol at the ultrasonographic detection of a CL plus injection of 5000 IU hCG immediately be...
Use of a GnRH antagonist, antarelix, associated or not with hCG, to control ovulation in cyclic pony mares. The GnRH antagonist antarelix (Teverelix) was administered to mares (0.01 mg/kg, i.v., twice a day) during the periovulatory period. In Experiment 1, 20 mares were divided into a treated (A3d-) and a control (Control-) group. A3d- mares received antarelix for 3 days from the day when the dominant follicle (F1) reached 32 mm (D0). In Experiment 2, 10 mares were divided into a treated (A6d+) and a control (Control+) group. A6d+ mares received antarelix for 6 days from D0 and hCG was injected in all animals (1600 IU, i.v.) on D1. Pregnancies were determined 13 days after ovulation. In both experi...
Cloning and nucleotide sequence of the equine and elk pituitary pre-prolactin cDNA. We report the equine (Equs equs) and elk (Cervus elaphus) pituitary pre-prolactin (PRL) cDNA cloning, and their nucleotide and deduced amino acid sequences. Pre-PRL cDNA was obtained by RNA ligation mediated-rapid amplification of cDNA ends (RLM-RACE) and polymerase chain reaction (PCR). The elk pre-PRL cDNA exhibits two polymorphisms at positions 96 and 672, which are silent since they encode for the same amino acids, proline and isoleucine, respectively. We found no polymorphisms in the equine pre-PRL cDNA. The deduced amino acid sequence of the equine pre-PRL is 99% identical to the previou...
Development and validation of a specific radioimmunoassay for equine osteocalcin. This study describes for the first time the development and validation of a sensitive and specific radioimmunoassay (RIA) for equine osteocalcin (OC) quantification using purified equine OC as standard, tracer, and immunogen for antibody formation in rabbits. The assay allowed to measure equine serum OC levels with a sensitivity of 0.2 ng/mL. Immunoreactive serum OC values of clinically normal, different-aged horses ranged from 3.68 to 127.31 ng/mL. Intra- and inter-assay coefficients of variation (CV) were 6.2 and 8.2%, respectively. Serial equine serum sample dilutions were linear. The recov...
Effects of dexamethasone, glucose infusion, adrenocorticotropin, and propylthiouracil on plasma leptin concentrations in horses. In experiment 1, nine light horse geldings (three 3 x 3 Latin squares) received dexamethasone (DEX; 125 microg/kg BW, i.m.), glucose (0.2 g/kg BW, i.v.), or nothing (control) once per day for 4 days. DEX increased (P < 0.001) glucose, insulin, and leptin concentrations and resulted in a delayed increase (P < 0.001) in IGF-I concentrations. In experiment 2, mares were similarly treated with DEX (n = 6) or vehicle (n = 6). DEX again increased (P < 0.01) glucose, insulin, and leptin concentrations; the delayed elevation in IGF-I concentrations occurred on day 10, 12, and 19, relative to ...
Effects of frequency of treatment with recombinant equine somatotropin on selected biological responses in geldings. Two experiments compared the efficacies of different treatment frequencies for recombinant equine somatotropin (eST). In Experiment 1, five geldings received daily injections of eST at 20 microg/kg of body weight, and five received every-other-day injections at 40 microg/kg of body weight, for a total of 30 days. Plasma glucose (P=0.0001), insulin (P=0.0135), and non-esterified fatty acid (NEFA, P=0.0001) concentrations increased, and plasma urea nitrogen (PUN) concentrations decreased (P=0.0001), in both groups, and only minor differences (P<0.05) occurred between the two groups. Insulin-like...