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Vaughn SA, Berghaus LJ, Hart KA. Assessing the effects of ex vivo hormonal exposure on oxidative responses in equine leukocytes: A preliminary study. Vet Immunol Immunopathol 2024; 276:110827. [PMID: 39293133 DOI: 10.1016/j.vetimm.2024.110827] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 08/24/2024] [Accepted: 09/04/2024] [Indexed: 09/20/2024]
Abstract
Breed differences exist between horses and ponies in circulating concentrations of several hormones, notably ACTH and insulin. These hormones regulate stress and metabolic responses, but in other species, they also impact leukocyte oxidant responses. The effects of these hormones on equine leukocytes have not been evaluated to date. If equine leukocytes are similarly regulated, breed differences in increased plasma hormone concentrations or altered sensitivity to them at the leukocyte level could result in breed-related differences in oxidant responses or oxidative status. The objective of this study was therefore to determine the effects of ex vivo exposure to adrenocorticotropic hormone (ACTH), α-melanocyte stimulating hormone (α-MSH), insulin, or leptin on reactive oxygen species (ROS) production from leukocytes isolated from horses and ponies. We hypothesized that ACTH, α-MSH, insulin, and leptin would alter oxidant responses from equine leukocytes in a breed specific manner. Blood was collected from 10 apparently healthy Quarter horses and seven Welsh ponies for isolation of neutrophils and peripheral blood mononuclear cells (PBMCs) via density gradient centrifugation. Cells were incubated with media (negative control), microbial antigens (positive control), or ACTH, α-MSH, leptin, or insulin for two hours. Induced ROS production was quantified with a previously validated fluorometric assay. Data was compared within groups by comparing a stimulant within a group (horses or ponies) to baseline, between groups by comparing horse response to pony response, and among stimulants using one- and two-way, repeated measures ANOVA (P<0.05). There was no significant effect of breed on basal, microbial-induced, or hormone-induced ROS production from neutrophils (P=0.465) or PBMCs (P=0.749), but in neutrophils, a significant interaction between breed and stimulant was present (P=0.037). ROS production from PBMCs from horses after hormone exposure did not differ from cells exposed to media only (P=0.1520-0.8180). Similarly, neither leptin nor insulin exposure significantly induced ROS production from PBMCs from ponies (P= 0.2645 and 0.4678 respectively), but exposure to ACTH or α-MSH induced a significant increase in ROS production (P=0.0441 and 0.0440 respectively) compared to unstimulated cells. Hormones that vary in availability among breeds may induce ex vivo pro-oxidant responses in equine leukocytes, but specific effects are breed-, leukocyte type-, and hormone-dependent. Breed differences in hormonally induced leukocyte ROS production may warrant further investigation in the context of circulating oxidative stress and how this might relate to future disease risk.
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Affiliation(s)
- Sarah A Vaughn
- Department of Large Animal Medicine, University of Georgia College of Veterinary Medicine, Athens, GA, USA.
| | - Londa J Berghaus
- Department of Large Animal Medicine, University of Georgia College of Veterinary Medicine, Athens, GA, USA
| | - Kelsey A Hart
- Department of Large Animal Medicine, University of Georgia College of Veterinary Medicine, Athens, GA, USA.
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2
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Sundra T, Kelty E, Rossi G, Rendle D. Retrospective assessment of the use of extended-release cabergoline in the management of equine pituitary pars intermedia dysfunction. Front Vet Sci 2024; 11:1332337. [PMID: 38511195 PMCID: PMC10951098 DOI: 10.3389/fvets.2024.1332337] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2023] [Accepted: 02/23/2024] [Indexed: 03/22/2024] Open
Abstract
Introduction Dopaminergic agonists are accepted as the most effective treatment for pituitary pars intermedia dysfunction. However, some horses are refractory to daily oral pergolide, the recommended registered treatment. Extended-release cabergoline (ERC) injection may offer an alternative. The objective of this retrospective case series was to describe clinical and endocrinological responses to ERC. Methods Medical records of horses treated with weekly intramuscular injections of ERC (5 mg/mL, BOVA Aus) at either 0.01 mg/kg (high dose, HD) (n = 10) or 0.005 mg/kg (low dose, LD) (n = 30) were reviewed. Short-term ACTH responses were assessed at 5-8 days using a Wilcoxon signed ranked test. Longer-term ACTH responses (30 to 365 days) were assessed using generalised estimating equations. Results Five to eight days after the first dose of LDERC, median adrenocorticotropic hormone (ACTH) concentration was lower (p = 0.001), changing from 153 pg/mL (IQR: 78, 331) to 57 pg/mL (IQR: 30, 102). With HDERC, median ACTH concentration was also 153 pg/mL (IQR: 96, 185) before and then 56 pg/mL (IQR: 29, 86) after 5-8 days of treatment (p = 0.047). Over 12 months of treatment, ACTH concentration ranged from 14 to >1,250 pg/mL (median: 51 pg/mL) in horses treated with LDERC and 20 to 472 pg/mL (median: 50 pg/mL) in horses treated with HDERC. Measurements remained above the seasonal reference range in 39.3 and 52.3% of horses treated with LDERC and HDERC, respectively. Clinical improvement was reported by owners in 78.3 and 100% of horses treated with LDERC and HDERC, respectively. Partial, self-limiting inappetence was reported in 30.0% of LDERC and 60% HDERC cases. Seven horses exhibited lethargy (5 LDERC, 2 HDERC). Insulin concentrations measured 30 days post-ERC treatment were no different from baseline. Discussion Clinical and endocrinological responses were consistent with results of previous reports of oral pergolide treatment. Weekly injection of ERC may be an effective alternative to pergolide; the 0.005 mg/kg dose appeared to be as effective, with less risk of inappetence, than the 0.01 mg/kg dose that has been reported previously.
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Affiliation(s)
- Tania Sundra
- Avon Ridge Equine Veterinary Services, Brigadoon, WA, Australia
- School of Veterinary Medicine, Murdoch University, Murdoch, WA, Australia
| | - Erin Kelty
- School of Population and Global Health, University of Western Australia, Crawley, WA, Australia
| | - Gabriele Rossi
- School of Veterinary Medicine, Murdoch University, Murdoch, WA, Australia
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Bamford NJ, Stewart AJ, El-Hage CM, Bertin FR, Bailey SR. Investigation of breed differences in plasma adrenocorticotropic hormone concentrations among healthy horses and ponies. Vet J 2023; 296-297:105995. [PMID: 37207985 DOI: 10.1016/j.tvjl.2023.105995] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2022] [Revised: 04/06/2023] [Accepted: 05/16/2023] [Indexed: 05/21/2023]
Abstract
Plasma adrenocorticotropic hormone (ACTH) concentration is commonly measured to diagnose pituitary pars intermedia dysfunction (PPID). Several intrinsic and extrinsic factors affect ACTH concentrations, including breed. The objective of this study was to prospectively compare plasma ACTH concentrations among different breeds of mature horses and ponies. Three breed groups comprised Thoroughbred horses (n = 127), Shetland ponies (n = 131) and ponies of non-Shetland breeds (n = 141). Enrolled animals did not show any signs of illness, lameness or clinical signs consistent with PPID. Blood samples were collected 6 months apart, around the autumn equinox and spring equinox, and plasma concentrations of ACTH were measured by chemiluminescent immunoassay. Pairwise breed comparisons within each season were performed on log transformed data using the Tukey test. Estimated mean differences in ACTH concentrations were expressed as fold difference with 95 % confidence intervals (CI). Reference intervals for each breed group per season were calculated using non-parametric methods. In autumn, higher ACTH concentrations were found among non-Shetland pony breeds compared with Thoroughbreds (1.55 fold higher; 95 % CI, 1.35-1.77; P < 0.001), and in Shetland ponies compared with Thoroughbreds (2.67 fold higher; 95 % CI, 2.33-3.08; P < 0.001) and non-Shetland pony breeds (1.73 fold higher; 95 % CI, 1.51-1.98; P < 0.001). In spring, no differences were identified among breed groups (all P > 0.05). Reference intervals were similar among breed groups in spring, but upper limits for ACTH concentrations were markedly different between Thoroughbred horses and pony breeds in autumn. These findings emphasise that breed should be accounted for when determining and interpreting reference intervals for ACTH concentrations among healthy horses and ponies in autumn.
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Affiliation(s)
- N J Bamford
- Melbourne Veterinary School, The Universtiy of Melbourne, Building 400, Parkville, Victoria 3010, Australia.
| | - A J Stewart
- School of Veterinary Science, The University of Queensland, Building 4114, Gatton, Queensland 4343, Australia
| | - C M El-Hage
- Melbourne Veterinary School, The Universtiy of Melbourne, Building 400, Parkville, Victoria 3010, Australia
| | - F R Bertin
- School of Veterinary Science, The University of Queensland, Building 4114, Gatton, Queensland 4343, Australia
| | - S R Bailey
- Melbourne Veterinary School, The Universtiy of Melbourne, Building 400, Parkville, Victoria 3010, Australia
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DeNotta S, McFarlane D. Immunosenescence and inflammaging in the aged horse. Immun Ageing 2023; 20:2. [PMID: 36609345 PMCID: PMC9817422 DOI: 10.1186/s12979-022-00325-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 12/21/2022] [Indexed: 01/09/2023]
Abstract
The equine population in the United States and worldwide now includes a higher percentage of geriatric horses than ever previously recorded, and as methods to treat and manage elderly equids are developed and refined, this aging population will likely continue to expand. A better understanding of how horses age and the effect of age on immunity and disease susceptibility is needed to enable targeted preventative healthcare strategies for aged horses. This review article outlines the current state of knowledge regarding the effect of aging on immunity, vaccine responsiveness, and disease risk in the horse, highlighting similarities and differences to what is observed in aged humans. Horses show similar but milder age-related alterations in immune function to those reported in people. Decreases in lymphocyte proliferation and antibody production and diminished response to vaccination have all been documented in elderly horses, however, increased risk of infectious disease is not commonly reported. Aged horses also show evidence of a proinflammatory state (inflammaging) yet appear less susceptible to the chronic diseases of people for which inflammation is a risk factor. Information is currently lacking as to why the horse does not experience the same risk of age-related disease (e.g., cancer, heart disease, neurodegeneration) as people, although a lack of negative lifestyle habits, differences in diet, exercise, genetics and physiology may all contribute to improved health outcomes in the older horse.
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Affiliation(s)
- Sally DeNotta
- grid.15276.370000 0004 1936 8091Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL USA
| | - Dianne McFarlane
- grid.15276.370000 0004 1936 8091Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL USA
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5
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Pituitary Pars Intermedia Dysfunction (PPID) in Horses. Vet Sci 2022; 9:vetsci9100556. [PMID: 36288169 PMCID: PMC9611634 DOI: 10.3390/vetsci9100556] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/25/2022] [Accepted: 10/04/2022] [Indexed: 12/12/2022] Open
Abstract
Substantial morbidity results from pituitary pars intermedia dysfunction (PPID) which is often underestimated by owners and veterinarians. Clinical signs, pathophysiology, diagnostic tests, and treatment protocols of this condition are reviewed. The importance of improved recognition of early clinical signs and diagnosis are highlighted, as initiation of treatment will result in improved quality of life. Future research should be targeted at improving the accuracy of the diagnosis of PPID, as basal adrenocorticotropic hormone (ACTH) concentration can lack sensitivity and thyrotropin releasing hormone (TRH) used to assess ACTH response to TRH stimulation is not commercially available as a sterile registered product in many countries. The relationship between PPID and insulin dysregulation and its association with laminitis, as well as additional management practices and long-term responses to treatment with pergolide also require further investigation.
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Emet DC, Ozon A, Alikasifoglu A, Kandemir N, Gonc N. Alpha-Melanocyte-Stimulating Hormone is Elevated in Hypothalamic Obesity Associated with Childhood Craniopharyngioma. Obesity (Silver Spring) 2021; 29:402-408. [PMID: 33491320 DOI: 10.1002/oby.23087] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/24/2020] [Accepted: 11/05/2020] [Indexed: 11/06/2022]
Abstract
OBJECTIVE The purpose of this study was to investigate the peripheral concentrations of leptin and neuropeptides taking part in the melanocortin pathway in hypothalamic obesity (HO) associated with craniopharyngioma (CP) and to find a peripheral marker for diagnosis. METHODS Thirty-one patients (52% girls; median age 16 years) with CP were enrolled in the study group. They were grouped as CP with obesity (CPobesity , n = 17) and CP without obesity (CPnonobesity , n = 14). Two control groups without CP consisted of 27 children with obesity (OC) (55% girls; median age 13.8 years) and 25 children without obesity (normal control [NC]) (72% girls; median age 14.5 years). Obesity was defined as BMI percentile ≥ 95%. Fasting serum concentrations of leptin, brain-derived neurotrophic factor (BDNF), and alpha-melanocyte-stimulating hormone (α-MSH) were measured in the groups. RESULTS Leptin and BDNF concentrations were correlated with BMI SD score (SDS) in controls (OC + NC) and CP. However, there was no correlation between α-MSH and BMI-SDS in CP or control groups. After adjusting for age, sex, and BMI-SDS, α-MSH was found to be significantly higher in CPobesity than in other groups, whereas leptin and BDNF were comparable among the four groups. CONCLUSIONS Serum BDNF, just like leptin, increased with BMI, regardless of hypothalamic damage. On the contrary, α-MSH concentration was significantly high in HO, designating a potential biomarker for HO in CP.
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Affiliation(s)
- Dicle Canoruc Emet
- Department of Pediatric Endocrinology, Hacettepe University, Ankara, Turkey
| | - Alev Ozon
- Department of Pediatric Endocrinology, Hacettepe University, Ankara, Turkey
| | - Ayfer Alikasifoglu
- Department of Pediatric Endocrinology, Hacettepe University, Ankara, Turkey
| | - Nurgun Kandemir
- Department of Pediatric Endocrinology, Hacettepe University, Ankara, Turkey
| | - Nazlı Gonc
- Department of Pediatric Endocrinology, Hacettepe University, Ankara, Turkey
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Oberhaus EL, Thompson DL, Kerrigan LE, Chapman AM. Plasma prolactin, thyroid-stimulating hormone, melanocyte-stimulating hormone, and adrenocorticotropin responses to thyrotropin-releasing hormone in mares treated with detomidine and butorphanol. Domest Anim Endocrinol 2021; 74:106536. [PMID: 32871339 DOI: 10.1016/j.domaniend.2020.106536] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/02/2020] [Revised: 06/25/2020] [Accepted: 08/04/2020] [Indexed: 10/23/2022]
Abstract
Stress or excitement is a concern when performing endocrine tests on fractious horses. Sedation may be a solution; however, perturbation of test results may preclude useful information. Thyrotropin-releasing hormone (TRH) is a known stimulator of prolactin, thyroid-stimulating hormone (TSH), melanocyte-stimulating hormone (MSH), and ACTH. Thyrotropin-releasing hormone-induced ACTH is a diagnostic tool for the assessment of endocrinopathies such as pituitary pars intermedia dysfunction. It is unknown if drugs commonly used for sedation alter endocrine responses. The objective of this study was to assess the effects of detomidine (DET) and butorphanol on endocrine responses to TRH. Nine light horse mares were used in a replicated 3 × 3 Latin square with the following treatments: saline, DET, and detomidine + butorphanol (DET/BUT), all administered intravenously at 0.01 mg/kg BW. A 1-wk washout period was allowed between phases, all of which were performed in December. Blood samples were collected at -10 and 0 min before treatment and 5 and 10 min post-treatment. Administration of 1 mg TRH occurred 10 min post-treatment, and blood sampling continued 5, 10, 20, and 30 min post-TRH. Data were analyzed by ANOVA as a replicated Latin square with repeated sampling. Plasma prolactin increased (P < 0.0001) after TRH in all groups, rapidly peaking at 5 min in drug-treated mares and 40 min in saline-treated mares. The peak prolactin response to TRH was 2-fold higher (P < 0.0001) in saline-treated mares compared with those drug-treated. A peak rise in plasma TSH was observed in DET/BUT-treated mares 10 min after TSH and was greater (P ≤ 0.007) compared with DET- and saline-treated mares. Plasma MSH was stimulated (P = 0.001) by DET and DET/BUT before TRH, and the peak MSH response to TRH was greater (P < 0.0001) in drug-treated mares, although not hastened as observed with prolactin and TSH. A peak rise in ACTH was observed in drug-treated mares 5 min after administration of TRH, whereas a peak rise was observed in control mares 10 min post-TRH and was almost 2-fold lower (P = 0.05) than the peak observed in DET and DET/BUT-treated mares. Basal ACTH concentrations were not affected by DET or DET/BUT, indicating that sedation with these compounds may be achieved when needing to measure basal plasma ACTH. Treatment with DET and DET/BUT did alter the prolactin, TSH, MSH, and ACTH responses to TRH; therefore, the use of these drugs may not be advisable when assessing endocrine responses to TRH stimulation.
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Affiliation(s)
- E L Oberhaus
- School of Animal Sciences, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge, LA, USA.
| | - D L Thompson
- School of Animal Sciences, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge, LA, USA
| | - L E Kerrigan
- School of Animal Sciences, Louisiana Agricultural Experiment Station, Louisiana State University Agricultural Center, Baton Rouge, LA, USA
| | - A M Chapman
- Department of Veterinary Clinical Sciences, Louisiana State University School of Veterinary Medicine, Baton Rouge, LA, USA
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Bamford NJ, Harris PA, Bailey SR. Circannual variation in plasma adrenocorticotropic hormone concentrations and dexamethasone suppression test results in Standardbred horses, Andalusian horses and mixed-breed ponies. Aust Vet J 2020; 98:616-621. [PMID: 33001453 DOI: 10.1111/avj.13022] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2020] [Revised: 07/18/2020] [Accepted: 09/04/2020] [Indexed: 01/23/2023]
Abstract
OBJECTIVE To compare circannual plasma concentrations of adrenocorticotropic hormone (ACTH) and seasonal dexamethasone suppression test (DST) results between three different equine breed groups. METHODS Six Standardbred horses, six Andalusian horses and six mixed-breed ponies were followed over a 1-year period, during which time groups were managed identically. Blood samples were collected monthly (around the autumn equinox) or in every second month (other times of the year) for the determination of plasma ACTH concentrations using a chemiluminescent immunoassay. Overnight DSTs were performed quarterly, with suppression of plasma cortisol to below 27 nmol/L at 19 h considered a normal result. RESULTS Seasonal variation in plasma ACTH concentrations was present among all breed groups with, as expected, higher levels detected around the autumn equinox, from February to April (P < 0.001). Plasma ACTH concentrations were different between breed groups in March, with higher levels in Andalusians compared with Standardbreds (P = 0.048) and in ponies compared with Standardbreds (P = 0.010). Suppression of cortisol during the DST was normal for all animals in winter, spring and summer, but five Andalusians and three ponies returned abnormally high results in autumn, compared with zero Standardbreds. CONCLUSION Higher plasma ACTH concentrations and more false-positive DST results were obtained during autumn in ponies and Andalusian horses when compared with Standardbred horses. Potential differences between breeds should be considered when interpreting test results for horses and ponies that are evaluated for pituitary pars intermedia dysfunction. Further work is recommended to establish population-based reference intervals and clinical cut-off values for ACTH in different equine breeds.
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Affiliation(s)
- N J Bamford
- Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia
| | - P A Harris
- Equine Studies Group, WALTHAM Petcare Science Institute, Melton Mowbray, Leicestershire, UK
| | - S R Bailey
- Melbourne Veterinary School, The University of Melbourne, Parkville, Victoria, Australia
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Zak A, Siwinska N, Elzinga S, Barker VD, Stefaniak T, Schanbacher BJ, Place NJ, Niedzwiedz A, Adams AA. Effects of advanced age and pituitary pars intermedia dysfunction on components of the acute phase reaction in horses. Domest Anim Endocrinol 2020; 72:106476. [PMID: 32380311 DOI: 10.1016/j.domaniend.2020.106476] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2019] [Revised: 02/12/2020] [Accepted: 03/01/2020] [Indexed: 11/24/2022]
Abstract
Age, neurodegenerative disorders, and dysfunction of insulin secretion may be correlated with increased systemic concentrations of acute phase markers. Thus, the study aimed to determine the effect of age, pituitary pars intermedia dysfunction (PPID), and insulin dysregulation (ID) associated with PPID, on markers of the acute phase reaction. Twenty-nine mix-breed horses of both sexes were classified into groups: (1) healthy adult controls, (2) healthy non-PPID geriatric horses, (3) PPID ID+ horses, and (4) PPID ID- horses. Whole blood proinflammatory cytokine gene expression and serum concentrations of pro- and anti-inflammatory cytokines and acute phase proteins were measured. The data were analyzed using the Mann-Whitney U-test, and correlations between groups of data were assessed using Spearman's correlation coefficient. The tests were statistically significant if P < 0.05. No differences in the whole blood cytokine gene expression, serum cytokine concentrations, or acute phase proteins were noted between the groups. In the PPID ID group, there was a strong correlation between the ACTH concentration after the administration of thyrotropin-releasing hormone and the expression of IL-8 (r = 0.941; P = 0.0321). In the PPID ID+ group, there was a strong correlation between basal insulin concentrations and serum amyloid A (SAA; r = 0.936; P = 0.0083) as well as between postprandial insulin concentrations and SAA (r = 0.965; P = 0.001). These data suggest that neurodegeneration in horses moderately affects circulating markers of inflammation and that ID in horses with PPID influences acute phase inflammatory markers.
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Affiliation(s)
- A Zak
- Department of Internal Diseases with Clinic for Horses, Dogs and Cats, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland.
| | - N Siwinska
- Department of Internal Diseases with Clinic for Horses, Dogs and Cats, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | - S Elzinga
- Department of Veterinary Science, MH Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA
| | - V D Barker
- Department of Veterinary Science, MH Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA
| | - T Stefaniak
- Department of Immunology, Pathophysiology and Veterinary Preventive Medicine, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | - B J Schanbacher
- Department of Population Medicine & Diagnostic Sciences, Animal Health Diagnostic Center, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - N J Place
- Department of Population Medicine & Diagnostic Sciences, Animal Health Diagnostic Center, College of Veterinary Medicine, Cornell University, Ithaca, NY 14853, USA
| | - A Niedzwiedz
- Department of Internal Diseases with Clinic for Horses, Dogs and Cats, Wroclaw University of Environmental and Life Sciences, Wroclaw, Poland
| | - A A Adams
- Department of Veterinary Science, MH Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA
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10
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Żak A, Siwińska N, Chełmecka E, Bażanów B, Romuk E, Adams A, Niedźwiedź A, Stygar D. Effects of Advanced Age, Pituitary Pars Intermedia Dysfunction and Insulin Dysregulation on Serum Antioxidant Markers in Horses. Antioxidants (Basel) 2020; 9:antiox9050444. [PMID: 32455574 PMCID: PMC7278619 DOI: 10.3390/antiox9050444] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2020] [Revised: 05/16/2020] [Accepted: 05/19/2020] [Indexed: 11/16/2022] Open
Abstract
The study aims to assess the impact of age, pituitary pars intermedia dysfunction (PPID) and insulin dysregulation (ID) in horses on selected oxidative stress markers. The study includes 32 horses, divided into three groups: “young” adult group (aged 8–16 years old) “geriatric” group (aged 18–24 years old) and the “PPID” group (aged 15–31 years old). The PPID group was further divided into two subgroups: PPID ID+ and PPID ID− based on presence or absence of ID. We measured serum antioxidant stress markers in all horses: total oxidant status (TOS), total antioxidant capacity (TAC), ceruloplasmin (CER), lipofuscin (LPS), malondialdehyde (MDA) and thiols concentrations (containing sulfhydryl group -SH) as well as enzymatic systems: total superoxide dismutase (SOD), cytoplasmic SOD (CuZnSOD), mitochondrial SOD activity (MnSOD). Total serum thiols were significantly lower in the geriatric group and in the PPID group compared to the young group. The MnSOD concentration was higher in the PPID ID+ group compared to the PPID ID−. LPS and MDA concentrations were lower in the PPID ID+ group compared to the PPID ID− group. In the selected study groups of horses, older age, the presence of PPID and ID in the case of PPID had no effect on the studied oxidative stress markers.
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Affiliation(s)
- Agnieszka Żak
- Department of Immunology, Pathophysiology and Veterinary Preventive Medicine, University of Environmental and Life Sciences, 50-375 Wroclaw, Poland
- Department of Internal Diseases with Clinic for Horses, Dogs and Cats, Wroclaw University of Environmental and Life Sciences, 50-366 Wroclaw, Poland; (N.S.); (A.N.)
- Correspondence:
| | - Natalia Siwińska
- Department of Internal Diseases with Clinic for Horses, Dogs and Cats, Wroclaw University of Environmental and Life Sciences, 50-366 Wroclaw, Poland; (N.S.); (A.N.)
| | - Elżbieta Chełmecka
- Department of Statistics, Department of Instrumental Analysis, Faculty of Pharmaceutical Sciences in Sosnowiec Medical University of Silesia, 40-055 Katowice, Poland;
| | - Barbara Bażanów
- Department of Pathology, Wroclaw University of Environmental and Life Sciences, 50-375 Wroclaw, Poland;
| | - Ewa Romuk
- Department of Biochemistry, Faculty of Medical Sciences in Zabrze, Medical University of Silesia, 41-808 Katowice, Poland;
| | - Amanda Adams
- Department of Veterinary Science, MH Gluck Equine Research Center, University of Kentucky, Lexington, KY 40546, USA;
| | - Artur Niedźwiedź
- Department of Internal Diseases with Clinic for Horses, Dogs and Cats, Wroclaw University of Environmental and Life Sciences, 50-366 Wroclaw, Poland; (N.S.); (A.N.)
| | - Dominika Stygar
- Department of Physiology, School of Medicine with the Division of Dentistry in Zabrze, Medical University of Silesia, 41-808 Katowice, Poland;
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Hu K, Stewart AJ, Yuen KY, Hinrichsen S, Dryburgh EL, Bertin FR. The effect of freeze-thaw cycles on determination of immunoreactive plasma adrenocorticotrophic hormone concentrations in horses. J Vet Intern Med 2020; 34:1350-1356. [PMID: 32255541 PMCID: PMC7255672 DOI: 10.1111/jvim.15771] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Accepted: 03/16/2020] [Indexed: 11/28/2022] Open
Abstract
Background Determination of plasma adrenocotrophic hormone (ACTH) concentration (endogenous or thyrotropin‐releasing hormone [TRH] stimulation test) is the most commonly used diagnostic test for pituitary pars intermedia dysfunction (PPID) in horses. Because ACTH is unstable, samples often are frozen to be shipped to laboratories or to allow for batch analysis of research samples. However, the effect of multiple freeze‐thaw cycles on equine ACTH is unknown. Objective To determine the effects of multiple freeze‐thaw cycles on immunoreactive ACTH concentration. Animals Twenty‐eight horses ranging from 10 to 27 years of age were used. Methods Prospective study. Horses were divided into 4 groups: group 1, PPID‐negative, without TRH stimulation; group 2, PPID‐negative, with TRH stimulation; group 3, PPID‐positive, without TRH stimulation; and group 4, PPID‐positive, with TRH stimulation. Whole blood was collected from each horse at baseline or 30 minutes after TRH stimulation. Immunoreactive plasma ACTH concentration was determined using a chemiluminescence assay. Plasma samples then were frozen at −80°C >24 hours, thawed at 4°C and reanalyzed for 5 freeze‐thaw cycles. Changes in plasma ACTH concentration were analyzed using a linear mixed‐effect model. Results Significant effects of freeze‐thaw cycles (P = .001) and PPID status (P = .04) on plasma ACTH concentration were observed, but no significant effect of TRH stimulation was identified. Conclusions and Clinical Importance The plasma ACTH concentration is altered by freeze‐thaw cycles, and the effect is observed sooner in horses with PPID. To diagnose PPID, multiple freeze‐thaw cycles should be avoided when measuring plasma ACTH concentration.
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Affiliation(s)
- Ke Hu
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Allison J Stewart
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Ka Y Yuen
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | - Sophia Hinrichsen
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
| | | | - François-René Bertin
- School of Veterinary Science, The University of Queensland, Gatton, Queensland, Australia
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Seddon RJ, Hews DK. Melanization, α-melanocyte stimulating hormone and steroid hormones in male western fence lizards from nine populations. Gen Comp Endocrinol 2020; 285:113287. [PMID: 31563645 DOI: 10.1016/j.ygcen.2019.113287] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2019] [Revised: 08/29/2019] [Accepted: 09/22/2019] [Indexed: 02/05/2023]
Abstract
Hormones can mediate suites of correlated traits. Melanocortins regulate melanin synthesis and elements of the melanocortin system can directly, and indirectly, affect a number of other traits, such as stress reactivity. Trait correlations within the melanocortin system have been studied mainly in birds and mammals but less so in reptiles. We examined adult male western fence lizards (Sceloporus occidentalis) and if melanization was correlated with plasma levels of three hormones, including peptide hormone α-melanocyte stimulating hormone (α-MSH), testosterone and corticosterone, and ectoparasite loads. This lizard is darker at higher elevations in California, and we compared five high-elevation and four low-elevation populations during comparable periods of the breeding season at each site. We first validated use of an α-MSH assay kit with lizard plasma. Since Anolis carolinensis is one of the few species with published values for α-MSH plasma levels, we assayed both Anolis and Sceloporus plasma and compared hormone values to those we generated for Anolis to the publish values. We also evaluated effects of different methods of storing spiked plasma pools on resulting α-MSH concentrations. Plasma levels of α-MSH did not differ significantly, but some populations differed significantly in mean corticosterone and mean testosterone. Combining all individuals from the nine populations, we found that individual variation in α-MSH was not associated with individual variation in melanization, but levels of α-MSH were positively associated with plasma testosterone and negatively associated with corticosterone. The lack of association between individual levels of melanization and expression of most other traits differs from a growing number of within-population studies of melanization, and we discuss what differences in physiological mechanisms could produce different hypothetical patterns. Circulating levels of -MSH are only one element of the melanocortin system; in situ synthesis of α-MSH by the skin and the diversity of melanocortin receptors could also contribute to variation in traits mediated by the melanocortin system and should be examined.
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Affiliation(s)
- Ryan J Seddon
- Department of Biology, Indiana State University, Terre Haute, IN 47809, USA.
| | - Diana K Hews
- Department of Biology, Indiana State University, Terre Haute, IN 47809, USA.
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13
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Thompson DL, Valencia NA, Walker NL, Oberhaus EL. Melanocyte-Stimulating Hormone Response to Exercise, Twitching, Epinephrine Injection, Substance P Injection, and Prostaglandin-F 2α Administration in Mares. J Equine Vet Sci 2019; 77:114-120. [PMID: 31133303 DOI: 10.1016/j.jevs.2019.03.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 03/12/2019] [Accepted: 03/12/2019] [Indexed: 12/01/2022]
Abstract
Five experiments were performed to test the hypothesis that α-melanocyte-stimulating hormone (MSH) is secreted in response to various stressors in horses similar to prolactin, growth hormone, and adrenocorticotropin (ACTH). There was considerable variation in resting concentrations of MSH and in the degree of stimulation in responders; thus all data sets were tested for heterogeneity of variance and corrected for as needed before analysis. In experiment 1, 12 mares were used in a switchback design to test the effect of a 2-minute exercise bout on MSH secretion. Plasma MSH concentrations were constant when mares were not exercised but increased (P < .05) immediately (2 minutes) after exercise and were still elevated 5 minutes later. In experiment 2, six mares were twitched for 2 minutes and six mares were not twitched. Twitching stimulated (P < .05) both MSH and ACTH relative to controls. Experiments 3, 4, and 5 tested the acute effects of intravenous injection of epinephrine at 5 μg/kg of body weight, intravenous injection of 100 μg substance P, and intramuscular injection of 10 mg prostaglandin-F2α in mares compared to controls (6, 5, and 6 mares per treatment group, respectively). Concentrations of MSH increased (P ≤ .05) after treatment in all three experiments. Plasma concentrations of ACTH also increased (P < .01) after administration of epinephrine and prostaglandin-F2α in experiments 3 and 5; plasma ACTH was not measured in experiment 1 or 4 because we have previously reported that exercise and substance P stimulate plasma ACTH concentrations. As hypothesized, MSH is secreted in response to various stimuli similar to that observed previously for prolactin, growth hormone, and ACTH.
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Affiliation(s)
- Donald L Thompson
- School of Animal Sciences, Louisiana Agricultural Experiment Station, LSU AgCenter, Baton Rouge, LA.
| | - Nicole Arana Valencia
- School of Animal Sciences, Louisiana Agricultural Experiment Station, LSU AgCenter, Baton Rouge, LA
| | - Neely L Walker
- School of Animal Sciences, Louisiana Agricultural Experiment Station, LSU AgCenter, Baton Rouge, LA
| | - Erin L Oberhaus
- School of Animal Sciences, Louisiana Agricultural Experiment Station, LSU AgCenter, Baton Rouge, LA
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Horn R, Bamford NJ, Afonso T, Sutherland M, Buckerfield J, Tan RHH, Secombe CJ, Stewart AJ, Bertin FR. Factors associated with survival, laminitis and insulin dysregulation in horses diagnosed with equine pituitary pars intermedia dysfunction. Equine Vet J 2018; 51:440-445. [DOI: 10.1111/evj.13041] [Citation(s) in RCA: 27] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2018] [Accepted: 11/02/2018] [Indexed: 12/29/2022]
Affiliation(s)
- R. Horn
- School of Veterinary Science The University of Queensland Gatton Queensland Australia
| | - N. J. Bamford
- Faculty of Veterinary and Agricultural Sciences The University of Melbourne Werribee Victoria Australia
| | - T. Afonso
- School of Animal and Veterinary Sciences The University of Adelaide Roseworthy South Australia Australia
| | - M. Sutherland
- Gisborne Veterinary Clinic Gisborne Victoria Australia
| | | | - R. H. H. Tan
- College of Public Health, Medical and Veterinary Sciences James Cook University Townsville Queensland Australia
- Samford Valley Veterinary Hospital Samford Queensland Australia
| | - C. J. Secombe
- School of Veterinary and Life Sciences Murdoch University Perth Western Australia Australia
| | - A. J. Stewart
- School of Veterinary Science The University of Queensland Gatton Queensland Australia
| | - F. R. Bertin
- School of Veterinary Science The University of Queensland Gatton Queensland Australia
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15
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Knowles EJ, Moreton-Clack MC, Shaw S, Harris PA, Elliott J, Menzies-Gow NJ. Plasma adrenocorticotropic hormone (ACTH) concentrations in ponies measured by two different assays suggests seasonal cross-reactivity or interference. Equine Vet J 2018; 50:672-677. [PMID: 29247453 DOI: 10.1111/evj.12797] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2017] [Accepted: 11/24/2017] [Indexed: 12/01/2022]
Abstract
BACKGROUND Analysis of plasma adrenocorticotropic hormone concentration [ACTH] aids diagnosis of pituitary pars intermedia dysfunction (PPID). Comparisons of the validated chemiluminescent-immunoassay (CI) and immunofluorescent (IF) assays are limited. OBJECTIVES To compare the results of [ACTH] analysis by CI and IF methods of samples collected in autumn and spring and assess cross-reactivity. STUDY DESIGN Method comparison. METHODS Plasma from nonlaminitic ponies was analysed concurrently using the IF and CI methods in autumn and the following spring. Diagnostic thresholds for the IF method were derived using ROC curves and Youden indices to correspond with CI thresholds. Assay specificity was assessed using commercially available ACTH fragments and degradation products of endogenous ACTH. RESULTS CI and IF methods yielded different results (P<0.001); mean differences (CI-IF), (95% confidence intervals): Autumn (n=99) 38.6 (30.6-46.5) pg/ml, Spring (n=88) 5.1 (3.9-6.3) pg/ml. The association between CI and IF results differed in autumn and spring, consistent with seasonally dependent cross-reactivity or interference. Good (κ=0.66-0.74) agreement was obtained for binary interpretation in spring between IF and CI using thresholds of >24 and >29 pg/ml respectively and in autumn between IF and CI using thresholds of >27 and >47 pg/ml respectively or >33 and >77 pg/ml respectively. Of 88 ponies with both spring and autumn samples, 56 (64%) exceeded a published autumn CI threshold (>47 pg/ml), of which 39 (70%) were below the equivalent threshold (<29 pg/ml) the following spring without treatment. The CI assay showed apparent increases in [ACTH] following addition of CLIP (ACTH 18-39). Degradation of ACTH during storage affected the assays differently. MAIN LIMITATIONS Limited numbers of PPID cases were included. Immunoreactivity of commercially available peptides may differ from their endogenous equivalents. CONCLUSIONS The methods yielded different absolute values but the agreement for binary classification was good. An altered pituitary secretome in autumn that affects apparent [ACTH] values is likely. The Summary is available in Spanish - see Supporting information.
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Affiliation(s)
- E J Knowles
- The Royal Veterinary College, North Mymms, Hatfield, Hertfordshire, UK.,The Bell Equine Veterinary Clinic, Mereworth, Kent, UK
| | | | - S Shaw
- Tosoh Bioscience Ltd, Redditch, Worcestershire, UK
| | - P A Harris
- Equine Studies Group, WALTHAM Centre for Pet Nutrition, Waltham on the Wolds, Leicestershire, UK
| | - J Elliott
- The Royal Veterinary College, North Mymms, Hatfield, Hertfordshire, UK
| | - N J Menzies-Gow
- The Royal Veterinary College, North Mymms, Hatfield, Hertfordshire, UK
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Abstract
The aging process in people is associated with changes in adaptive and innate immune responses. Similar changes occur in aged horses. Age-related progressive impairment in the ability to respond to pathogen challenge and an increased inflammatory reactivity may predispose geriatric horses to many diseases of old age. Specific recommendations for immune modification of older horses, including an age-appropriate vaccination schedule, are not currently available. In addition, the effect of old age on risk of infectious disease is poorly documented. More work is needed to better understand the interactions of age on immunity, vaccine response, and disease risk in horses.
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17
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McFarlane D, Banse H, Knych HK, Maxwell LK. Pharmacokinetic and pharmacodynamic properties of pergolide mesylate following long-term administration to horses with pituitary pars intermedia dysfunction. J Vet Pharmacol Ther 2016; 40:158-164. [DOI: 10.1111/jvp.12339] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/23/2015] [Accepted: 05/19/2016] [Indexed: 12/01/2022]
Affiliation(s)
- D. McFarlane
- Center for Veterinary Health Sciences; Physiological Sciences; Oklahoma State University; Stillwater OK USA
| | - H. Banse
- Center for Veterinary Health Sciences; Physiological Sciences; Oklahoma State University; Stillwater OK USA
| | - H. K. Knych
- K.L. Maddy Equine Analytical Chemistry Laboratory; School of Veterinary Medicine; University of California; Davis CA USA
| | - L. K. Maxwell
- Center for Veterinary Health Sciences; Physiological Sciences; Oklahoma State University; Stillwater OK USA
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18
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Goodale L, Frank N, Hermida P, D'Oench S. Evaluation of a thyrotropin-releasing hormone solution stored at room temperature for pituitary pars intermedia dysfunction testing in horses. Am J Vet Res 2016; 76:437-44. [PMID: 25909376 DOI: 10.2460/ajvr.76.5.437] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine whether plasma ACTH concentrations vary following administration of a thyrotropin-releasing hormone (TRH) solution prepared for research purposes and stored at -20°C (rTRH) or prepared by a compounding pharmacy and stored at room temperature (approx 22°C; cTRH). ANIMALS 34 adult horses. PROCEDURES The study consisted of 2 experiments. In experiment 1, each horse underwent 2 TRH stimulation tests separated by 24 hours; 10 horses were administered cTRH for the first test and rTRH for the second test (group 1), 10 horses were administered rTRH for the first test and cTRH for the second test (group 2), and 10 horses were administered rTRH for both tests (group 3). Plasma ACTH concentrations were measured at 0 (baseline) and 30 minutes after TRH administration and the delta ACTH responses (change in ACTH concentration after TRH administration) were calculated. In experiment 2, the design was the same as that for experiment 1 except there were 14 days between tests, ACTH was measured at 0 and 10 minutes after TRH administration, and 11, 9, and 10 horses were assigned to groups 1, 2, and 3, respectively. RESULTS Adverse effects associated with TRH administration included transient coughing and yawning. In experiment 1, the median delta ACTH response for the second test was significantly lower than that for the first test for all groups. In experiment 2, the median delta ACTH response did not differ significantly between the first and second tests for any group, ACTH concentrations after rTRH administration were positively correlated (rs = 0.95) with those after cTRH administration, and the mean ± SD bias in post-TRH ACTH concentration between rTRH and cTRH was 2.9 ± 12.4 pg/mL. CONCLUSIONS AND CLINICAL RELEVANCE Results indicated that the TRH stimulation test should not be repeated within 24 hours, and cTRH solution stored at room temperature could be used to effectively perform TRH stimulation testing in horses.
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Affiliation(s)
- Lindsay Goodale
- Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA 01536
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19
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Spelta CW. Equine pituitary pars intermedia dysfunction: current perspectives on diagnosis and management. VETERINARY MEDICINE-RESEARCH AND REPORTS 2015; 6:293-300. [PMID: 30101114 PMCID: PMC6067528 DOI: 10.2147/vmrr.s74191] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Equine pituitary pars intermedia dysfunction (PPID) is a neurodegenerative disease of the hypothalamus, resulting in the loss of dopaminergic inhibition of pars intermedia. An oxidative stress injury of unknown etiology has been suggested to initiate the neurodegeneration. While hypertrichosis (formerly known as hirsutism) is considered pathognomic for advanced disease, the antemortem diagnosis of subclinical and early disease has continued to prove difficult. Numerous tests have been used with varying sensitivities and specificities. The overnight dexamethasone suppression test, originally documented to have 100% sensitivity and specificity in horses with advanced disease, has proven to be less valuable in identifying early disease. Basal plasma adrenocorticotropin concentrations have improved sensitivity and specificity when sampled during the autumn months, and α-melanocyte-stimulating hormone, while not yet commercially available, shows promise as a sensitive and specific single sample test. Recent advances in our knowledge include the strong association between laminitis and hyperinsulinemia, both common clinical signs associated with PPID. The pathogenesis of hyperinsulinemia, laminitis, and their association with this disease is a focus of current research. The dopamine agonist pergolide mesylate is still the mainstay of medical management, with studies on oral bioavailability, pharmacokinetics, and long-term survival rates now published.
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20
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Selim S, Elo K, Jaakkola S, Karikoski N, Boston R, Reilas T, Särkijärvi S, Saastamoinen M, Kokkonen T. Relationships among Body Condition, Insulin Resistance and Subcutaneous Adipose Tissue Gene Expression during the Grazing Season in Mares. PLoS One 2015; 10:e0125968. [PMID: 25938677 PMCID: PMC4418745 DOI: 10.1371/journal.pone.0125968] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 03/27/2015] [Indexed: 01/09/2023] Open
Abstract
Obesity and insulin resistance have been shown to be risk factors for laminitis in horses. The objective of the study was to determine the effect of changes in body condition during the grazing season on insulin resistance and the expression of genes associated with obesity and insulin resistance in subcutaneous adipose tissue (SAT). Sixteen Finnhorse mares were grazing either on cultivated high-yielding pasture (CG) or semi-natural grassland (NG) from the end of May to the beginning of September. Body measurements, intravenous glucose tolerance test (IVGTT), and neck and tailhead SAT gene expressions were measured in May and September. At the end of grazing, CG had higher median body condition score (7 vs. 5.4, interquartile range 0.25 vs. 0.43; P=0.05) and body weight (618 kg vs. 572 kg ± 10.21 (mean ± SEM); P=0.02), and larger waist circumference (P=0.03) than NG. Neck fat thickness was not different between treatments. However, tailhead fat thickness was smaller in CG compared to NG in May (P=0.04), but this difference disappeared in September. Greater basal and peak insulin concentrations, and faster glucose clearance rate (P=0.03) during IVGTT were observed in CG compared to NG in September. A greater decrease in plasma non-esterified fatty acids during IVGTT (P<0.05) was noticed in CG compared to NG after grazing. There was down-regulation of insulin receptor, retinol binding protein 4, leptin, and monocyte chemoattractant protein-1, and up-regulation of adiponectin (ADIPOQ), adiponectin receptor 1 and stearoyl-CoA desaturase (SCD) gene expressions in SAT of both groups during the grazing season (P<0.05). Positive correlations were observed between ADIPOQ and its receptors and between SCD and ADIPOQ in SAT (P<0.01). In conclusion, grazing on CG had a moderate effect on responses during IVGTT, but did not trigger insulin resistance. Significant temporal differences in gene expression profiles were observed during the grazing season.
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Affiliation(s)
- Shaimaa Selim
- Department of Agricultural Sciences, P.O. Box 28, FI-00014 University of Helsinki, Helsinki, Finland
| | - Kari Elo
- Department of Agricultural Sciences, P.O. Box 28, FI-00014 University of Helsinki, Helsinki, Finland
- * E-mail:
| | - Seija Jaakkola
- Department of Agricultural Sciences, P.O. Box 28, FI-00014 University of Helsinki, Helsinki, Finland
| | - Ninja Karikoski
- Department of Equine and Small Animal Medicine, P.O. Box 57, FI-00014 University of Helsinki, Helsinki, Finland
| | - Ray Boston
- Department of Clinical Studies, New Bolton Center, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA 19104, United States of America
| | - Tiina Reilas
- Department of Green Technology, Natural Resources Institute Finland (Luke), Opistontie 10 A 1, FI-32100 Ypäjä, Finland
| | - Susanna Särkijärvi
- Department of Green Technology, Natural Resources Institute Finland (Luke), Opistontie 10 A 1, FI-32100 Ypäjä, Finland
| | - Markku Saastamoinen
- Department of Green Technology, Natural Resources Institute Finland (Luke), Opistontie 10 A 1, FI-32100 Ypäjä, Finland
| | - Tuomo Kokkonen
- Department of Agricultural Sciences, P.O. Box 28, FI-00014 University of Helsinki, Helsinki, Finland
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Neutrophil function in healthy aged horses and horses with pituitary dysfunction. Vet Immunol Immunopathol 2015; 165:99-106. [PMID: 25962580 DOI: 10.1016/j.vetimm.2015.04.006] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Revised: 04/01/2015] [Accepted: 04/23/2015] [Indexed: 11/23/2022]
Abstract
Immunosuppression leading to opportunist bacterial infection is a well-recognized sequela of equine pituitary pars intermedia dysfunction (PPID). The mechanisms responsible for immune dysfunction in PPID however, are as of yet poorly characterized. Horses with PPID have high concentrations of hormones known to impact immune function including α-melanocyte stimulating hormone (α-MSH) and insulin. α-MSH and related melanocortins have been shown in rodents and people to impair neutrophil function by decreasing superoxide production (known as oxidative burst activity), migration and adhesion. The goal of this study was to determine if neutrophil function is impaired in horses with PPID and, if so, to determine if plasma α-MSH or insulin concentration correlated with the severity of neutrophil dysfunction. Specifically, neutrophil phagocytosis, oxidative burst activity, chemotaxis and adhesion were assessed. Results of this study indicate that horses with PPID have reduced neutrophil function, characterized by decreased oxidative burst activity and adhesion. In addition, chemotaxis was greater in healthy aged horses than in young horses or aged horses with PPID. Plasma insulin: α-MSH ratio, but not individual hormone concentration was correlated to neutrophil oxidative burst activity. In summary, neutrophil function is impaired in horses with PPID, likely due to altered hormone concentrations and may contribute to increased risk of opportunistic infections. Whether regulation of hormone concentration profiles in horses with PPID using therapeutic intervention improves neutrophil function and reduces infections needs to be explored.
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22
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McFarlane D. Pathophysiology and clinical features of pituitarypars intermediadysfunction. EQUINE VET EDUC 2014. [DOI: 10.1111/eve.12237] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- D. McFarlane
- Center for Veterinary Health Sciences; Oklahoma State University; Stillwater USA
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23
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Arana Valencia N, Thompson DL, Oberhaus EL, Gilley RM. Long-term Treatment of Insulin-insensitive Mares with Cabergoline: Effects on Prolactin and Melanocyte Stimulating Hormone Responses to Sulpiride and on Indices of Insulin Sensitivity. J Equine Vet Sci 2014. [DOI: 10.1016/j.jevs.2013.12.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Panin M, Giurisato M, Peruffo A, Ballarin C, Cozzi B. Immunofluorescence evidence of melanotrophs in the pituitary of four odontocete species. An immunohistochemical study and a critical review of the literature. Ann Anat 2013; 195:512-21. [PMID: 23938266 DOI: 10.1016/j.aanat.2013.06.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2013] [Revised: 06/06/2013] [Accepted: 06/24/2013] [Indexed: 11/17/2022]
Abstract
Cetaceans share peculiar features of their pituitary glands, with a complete separation of pars distalis and pars nervosa by a dural septum and the absence of an intermediate lobe and cleft. In most mammals the pars intermedia is the main source of circulating α-melanocyte stimulating hormone (α-MSH), derived from a large precursor called proopiomelanocortin (POMC), which also generates adrenocorticotropic hormone (ACTH) in the adenohypophysis. The lack of an intermediate lobe in cetaceans led us to investigate whether their glands are able to produce α-MSH, and if this hormone is secreted by a distinct population of melanotrophs or by corticotrophs in the pars distalis. Immunofluorescence evidences seem to support the first assumption, with ACTH-immunoreactive (-ir) elements rarely overlapping with α-MSH-ir ones. The discovery of a population of true melanotrophs in the hypophysis of some odontocetes underscores the need for further research on the melanocortin system of cetaceans.
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Affiliation(s)
- Mattia Panin
- Department of Comparative Biomedicine and Food Science, University of Padova, Legnaro (PD), Italy.
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25
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Schreiber CM, Stewart AJ, Kwessi E, Behrend EN, Wright JC, Kemppainen RJ, Busch KA. Seasonal variation in results of diagnostic tests for pituitary pars intermedia dysfunction in older, clinically normal geldings. J Am Vet Med Assoc 2012; 241:241-8. [PMID: 22765372 DOI: 10.2460/javma.241.2.241] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine whether seasonal variations exist in endogenous plasma ACTH, plasma α-melanocyte-stimulating hormone (α-MSH), serum cortisol, and serum insulin concentrations and in the results of a dexamethasone suppression test for older, clinically normal geldings in Alabama. DESIGN Cohort study. ANIMALS 15 healthy mixed-breed geldings (median age, 14 years). PROCEDURES Sample collection was repeated monthly for 12 months. Dexamethasone (0.04 mg/kg [0.02 mg/lb], IM) was administered and cortisol concentrations were determined at 15 and 19 hours. Radioimmunoassays were used to measure ACTH, α-MSH, cortisol, and insulin concentrations at each testing time. Hormone concentrations were compared between months via repeated-measures ANOVA and correlated with age within each month. RESULTS A significant time effect was found between months for α-MSH and insulin concentrations. Endogenous cortisol and ACTH concentrations remained within existing reference ranges. Significant correlations were detected between age and ACTH concentration for several fall and winter months and between age and insulin concentration for September. CONCLUSIONS AND CLINICAL RELEVANCE Older horses have higher ACTH concentrations in several fall and winter months and higher insulin concentrations in September than do younger horses. Seasonally specific reference ranges are required for α-MSH and insulin concentrations, with significantly higher concentrations detected in the fall. Practitioners should be advised to submit samples only to local laboratories that can provide such reference ranges for their local geographic region.
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Affiliation(s)
- Christopher M Schreiber
- Department of Clinical Sciences, College of Veterinary Medicine, Auburn University, Auburn, AL 36849, USA
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26
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Cordero M, Brorsen BW, McFarlane D. Circadian and circannual rhythms of cortisol, ACTH, and α-melanocyte-stimulating hormone in healthy horses. Domest Anim Endocrinol 2012; 43:317-24. [PMID: 22717182 DOI: 10.1016/j.domaniend.2012.05.005] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/25/2012] [Revised: 05/13/2012] [Accepted: 05/13/2012] [Indexed: 10/28/2022]
Abstract
Cosinor analysis was used to evaluate whether pituitary and adrenal hormones exhibit circadian rhythmicity in horses. The effect of season and animal age on their respective rhythms was also determined. In addition, the usefulness of evaluating cortisol rhythmicity for the diagnosis of pituitary pars intermedia dysfunction (PPID) was assessed. Serum cortisol concentrations (P < 0.01), but not plasma ACTH or α-melanocyte-stimulating hormone (α-MSH), showed a significant circadian periodicity in horses. An effect of season on hormone concentration was observed with plasma ACTH and α-MSH concentration greater in the fall and cortisol concentration greater in the spring (P < 0.001). Age did not affect cortisol rhythm, but it did blunt the variation in cortisol concentration in horses, similar to what has been previously reported to occur in aged people and dogs. In addition, our results suggest that clinically and diagnostically normal, non-PPID-affected horses commonly have a loss of cortisol diurnal rhythm. Therefore, measurement of circadian rhythm is not an appropriate diagnostic test for PPID.
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Affiliation(s)
- M Cordero
- Department of Physiological Sciences, Center of Veterinary Health Sciences, Oklahoma State University, Stillwater, OK 74074, USA
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Funk R, Wooldridge A, Stewart A, Behrend E, Kemppainen R, Zhong Q, Johnson A. Seasonal Changes in the Combined Glucose-Insulin Tolerance Test in Normal Aged Horses. J Vet Intern Med 2012; 26:1035-41. [DOI: 10.1111/j.1939-1676.2012.00939.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Revised: 03/03/2012] [Accepted: 03/27/2012] [Indexed: 11/30/2022] Open
Affiliation(s)
| | | | | | | | - R.J. Kemppainen
- Department of Anatomy; College of Veterinary Medicine; Physiology and Pharmacology; Auburn University; Auburn; AL
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Mc Gowan TW, Pinchbeck GP, Mc Gowan CM. Evaluation of basal plasma α-melanocyte-stimulating hormone and adrenocorticotrophic hormone concentrations for the diagnosis of pituitary pars intermedia dysfunction from a population of aged horses. Equine Vet J 2012; 45:66-73. [PMID: 22563728 DOI: 10.1111/j.2042-3306.2012.00575.x] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
REASONS FOR PERFORMING STUDY The sensitivity and specificity of basal plasma α-melanocyte-stimulating hormone (α-MSH) and adrenocorticotrophic hormone (ACTH) for the diagnosis of pituitary pars intermedia dysfunction (PPID) has not been evaluated in a population-based study. OBJECTIVES To evaluate basal plasma α-MSH and ACTH concentrations for the diagnosis of PPID in a population of horses aged ≥ 15 years. METHODS Owner-reported data were obtained using a postal questionnaire distributed to an equestrian group. A subgroup of surveyed owners was visited and veterinary examination performed on horses aged ≥ 15 years. Blood samples were analysed for plasma α-MSH and ACTH concentrations. Seasonally adjusted cut-off values for α-MSH and ACTH concentrations for the diagnosis of PPID were obtained using Youden index values against a clinical gold standard diagnosis (hirsutism plus 3 or more clinical signs of PPID). RESULTS α-melanocyte-stimulating hormone and ACTH were highly correlated with each other and with clinical and historical indicators of PPID. The increase in both α-MSH and ACTH with increasing numbers of clinical signs in affected horses supports a spectrum of disease. Both variables were affected by season, with derived cut-off values being higher in autumn compared with other seasons. Sensitivity and specificity were moderate and good in nonautumn seasons (59 and 93%, respectively) for α-MSH using a cut-off of 52.0 pmol/l. Sensitivity and specificity were good in nonautumn seasons (80 and 83%, respectively) for ACTH using a cut-off of 29.7 pg/ml. For both α-MSH and ACTH, sensitivity and specificity were close to 100% for samples obtained during the autumn period. CONCLUSIONS AND POTENTIAL RELEVANCE Basal plasma α-MSH and ACTH had moderate-to-good sensitivity and specificity for the diagnosis of PPID, which improved substantially during the autumn period, suggesting this may be the ideal time to test. Further studies to develop seasonally adjusted reference intervals for different geographical locations are warranted.
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Affiliation(s)
- T W Mc Gowan
- Faculty of Natural Resources, Agriculture and Veterinary Science, University of Queensland, Gatton, Australia.
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The Effect of Season on the Histologic and Histomorphometric Appearance of the Equine Pituitary Gland. J Equine Vet Sci 2012. [DOI: 10.1016/j.jevs.2011.01.003] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
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30
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Holbrook TC, Tipton T, McFarlane D. Neutrophil and cytokine dysregulation in hyperinsulinemic obese horses. Vet Immunol Immunopathol 2011; 145:283-9. [PMID: 22169327 DOI: 10.1016/j.vetimm.2011.11.013] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2011] [Revised: 11/07/2011] [Accepted: 11/17/2011] [Indexed: 11/16/2022]
Abstract
Equine metabolic syndrome is characterized by obesity and regional adiposity coupled with evidence of recurrent laminitis. Although inflammation has been well characterized in several experimental models of acute laminitis, the inflammatory events associated with endocrinopathic laminitis are not well documented. The aim of this study was to characterize selected markers of inflammation in horses with clinical evidence of equine metabolic syndrome (EMS). Neutrophil phagocytosis and oxidative burst, as well as endogenous and stimulated cytokine expression were evaluated. A marked increase in neutrophil reactive oxygen species production upon phagocytosis was observed in horses with EMS that was strongly correlated to the blood insulin concentration. Increased oxidative burst activity of neutrophils in hyperinsulinemic horses may predispose horses with metabolic syndrome to laminitis. In contrast, peripheral blood cells of obese hyperinsulinemic horses showed decreased endogenous proinflammatory cytokine gene expression (IL-1 and IL-6) and similar cytokine response following immune stimulation compared to that of control horses. This may suggest that, unlike in people, cytokine-mediated inflammation does not increase in direct response to obesity or insulin resistance in horses. This species-specific disparity may explain the difference in clinical outcomes observed in obese horses compared to obese people.
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Affiliation(s)
- Todd C Holbrook
- Department of Veterinary Clinical Sciences, 002 BVMTH, Oklahoma State University, Stillwater, OK 74078, USA
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Holbrook TC, McFarlane D, Schott HC. Neuroendocrine and non-neuroendocrine markers of inflammation associated with performance in endurance horses. Equine Vet J 2011:123-8. [PMID: 21058993 DOI: 10.1111/j.2042-3306.2010.00256.x] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
REASONS FOR PERFORMING STUDY The inflammatory and neuroendocrine response to endurance exercise and relationship of these parameters to performance is not well documented in horses. HYPOTHESES OR OBJECTIVES: Evidence of systemic inflammation is associated with poor performance in horses competing in endurance events. METHODS Blood was collected prior to and at the finish or elimination point from horses competing in both the 80 and 160 km American Endurance Ride National Championship competitions in 2006. Immunoreactive alpha-melanocyte stimulating hormone (α-MSH) and tumour necrosis factor-alpha (TNF-α) were quantified utilising radioimmunoassay (RIA) and enzyme-linked immunosorbent assay (ELISA) techniques, respectively. The concentration of total thiobarbituric acid reactive substances (TBARS) was measured fluorometrically. RESULTS Thirty horses were included in the study. Endurance exercise was associated with a significant increase in TBARS in the 80 km group but not the 160 km group. TNF-α and α-MSH did not significantly change as a result of exercise in either distance group. Precompetition TBARS was significantly higher in horses that failed to finish the 80 km race, as well as when distances were combined. In addition, precompetition α-MSH was significantly lower in nonfinishers in the 160 km group. Furthermore, competition speed was positively correlated with precompetition α-MSH in the 80 km and negatively correlated with precompetition TNF-α when distances were combined. CONCLUSIONS Our results suggest that basal oxidative stress markers, circulating cytokines and anti-inflammatory neuroendocrine hormones appear to correlate with endurance performance in horses. POTENTIAL RELEVANCE Basal oxidative stress markers, circulating cytokines and anti-inflammatory neuroendocrine hormones may be predictive of athletic performance in endurance horses. Future studies evaluating the effect of training on these markers in endurance horses are warranted.
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Affiliation(s)
- T C Holbrook
- Department of Veterinary Clinical Sciences, Center for Veterinary Health Sciences, Oklahoma State University, Stillwater, Oklahoma, USA.
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McFarlane D, Paradis M, Zimmel D, Sykes B, Brorsen B, Sanchez A, Vainio K. The Effect of Geographic Location, Breed, and Pituitary Dysfunction on Seasonal Adrenocorticotropin and α-Melanocyte-Stimulating Hormone Plasma Concentrations in Horses. J Vet Intern Med 2011; 25:872-81. [DOI: 10.1111/j.1939-1676.2011.0745.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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Beech J, McFarlane D, Lindborg S, Sojka JE, Boston RC. α-Melanocyte—stimulating hormone and adrenocorticotropin concentrations in response to thyrotropin-releasing hormone and comparison with adrenocorticotropin concentration after domperidone administration in healthy horses and horses with pituitary pars intermedia dysfunction. J Am Vet Med Assoc 2011; 238:1305-15. [DOI: 10.2460/javma.238.10.1305] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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Hurcombe SDA. Hypothalamic-pituitary gland axis function and dysfunction in horses. Vet Clin North Am Equine Pract 2011; 27:1-17. [PMID: 21392650 DOI: 10.1016/j.cveq.2010.12.006] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
Abstract
Hypothalamic-pituitary (HP) dysfunction has been documented in a limited capacity in horses and foals associated with critical illness, stress, and pain. This article reviews species-specific details of anatomy, function, hormones, receptors, and testing of the HP axis in the horse. A discussion of critical care medicine relevant to HP dysfunction in the horse with some reference to current understanding in human medicine is made, focusing primarily on current and relevant literature. A brief mention of other conditions described in human and veterinary medicine is also provided for reference only, such as syndrome of inappropriate antidiuretic hormone secretion and other conditions.
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Affiliation(s)
- Samuel D A Hurcombe
- Department of Veterinary Clinical Sciences, Galbreath Equine Center, The Ohio State University, 601 Vernon L Tharp Street, Columbus, OH 43210, USA.
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Abstract
Equine pituitary pars intermedia dysfunction (PPID), also known as equine Cushing's syndrome, is a widely recognized disease of aged horses. Over the past two decades, the aged horse population has expanded significantly and in addition, client awareness of PPID has increased. As a result, there has been an increase in both diagnostic testing and treatment of the disease. This review focuses on the pathophysiology and clinical syndrome, as well as advances in diagnostic testing and treatment of PPID, with an emphasis on those findings that are new since the excellent comprehensive review by Schott in 2002.
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Affiliation(s)
- Dianne McFarlane
- Department of Physiological Sciences, 264 McElroy Hall, Oklahoma State University, Stillwater, OK 74078, USA.
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37
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Funk R, Stewart A, Wooldridge A, Kwessi E, Kemppainen R, Behrend E, Zhong Q, Johnson A. Seasonal Changes in Plasma Adrenocorticotropic Hormone and α-Melanocyte-Stimulating Hormone in Response to Thyrotropin-Releasing Hormone in Normal, Aged Horses. J Vet Intern Med 2011; 25:579-85. [DOI: 10.1111/j.1939-1676.2011.0712.x] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
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38
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Grenager N. How Does Cushing’s Disease Relate to Laminitis? Advances in Diagnosis and Treatment. J Equine Vet Sci 2010. [DOI: 10.1016/j.jevs.2010.07.015] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Frank N, Elliott S, Chameroy K, Tóth F, Chumbler N, McClamroch R. Association of Season and Pasture Grazing with Blood Hormone and Metabolite Concentrations in Horses with Presumed Pituitary Pars Intermedia Dysfunction. J Vet Intern Med 2010; 24:1167-75. [DOI: 10.1111/j.1939-1676.2010.0547.x] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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40
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Beech J, Boston RC, McFarlane D, Lindborg S. Evaluation of plasma ACTH, alpha-melanocyte-stimulating hormone, and insulin concentrations during various photoperiods in clinically normal horses and ponies and those with pituitary pars intermedia dysfunction. J Am Vet Med Assoc 2009; 235:715-22. [PMID: 19751169 DOI: 10.2460/javma.235.6.715] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To measure plasma ACTH, alpha-melanocyte-stimulating hormone (aloha-MSH), and insulin concentrations during various photoperiods between February and October in horses and ponies with and without pituitary pars intermedia dysfunction (PPID). DESIGN Cohort study. ANIMALS 13 clinically normal (control) ponies, 14 clinically normal (control) horses, 7 ponies with PPID, and 8 horses with PPID. PROCEDURES Blood samples were collected from February through October during 8 photoperiods: 1, February 13 through March 2; 2, April 4 through 6; 3, June 19 through 22; 4, August 6 through 7; 5, August 14 through 17; 6, September 4 through 6; 7, September 26 through 28; and 8, October 16 through 18. Plasma ACTH, alpha-MSH, and insulin concentrations at each photoperiod were compared among groups. RESULTS Log ACTH concentration was increased during photoperiod 4 through 8, compared with photoperiod 1 through 3, in all groups. In photoperiod 3 through 7, log ACTH concentrations were higher in horses and ponies with PPID, compared with values for control horses and ponies. alpha-Melanocyte-stimulating hormone (log and raw value) concentration was higher in photoperiod 2 through 8, compared with photoperiod 1, in control horses and ponies. In horses and ponies with PPID, log alpha-MSH concentration was higher in photoperiod 3 through 8, and alpha-MSH concentration was higher in photoperiod 4 through 8, compared with photoperiod 1. In control horses and ponies, plasma insulin concentration was lower in photoperiod 3 than in photoperiod 1. CONCLUSIONS AND CLINICAL RELEVANCE Plasma alpha-MSH and ACTH concentrations increased as daylight decreased from summer solstice (maximum daylight hours) to 12 hours of daylight.
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Affiliation(s)
- Jill Beech
- Department of Clinical Studies, New Bolton Center, University of Pennsylvania, Kennett Square, PA 19348, USA
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41
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Miller MA, Pardo ID, Jackson LP, Moore GE, Sojka JE. Correlation of Pituitary Histomorphometry with Adrenocorticotrophic Hormone Response to Domperidone Administration in the Diagnosis of Equine Pituitary Pars Intermedia Dysfunction. Vet Pathol 2008; 45:26-38. [PMID: 18192571 DOI: 10.1354/vp.45-1-26] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Functional evaluation of the pars intermedia (PI) is required for the early diagnosis of equine pituitary PI dysfunction (PPID), yet most assays target the hypothalamic-pituitary-adrenal axis, which regulates the pars anterior. In contrast, the PI is regulated by dopaminergic tone from hypothalamic neurons. Loss of dopaminergic inhibition is hypothesized to cause the PI hypertrophy and hyperplasia that result in the clinical manifestations of PPID. Domperidone, a dopamine receptor antagonist, should exacerbate the loss of dopaminergic inhibition in horses with PPID and increase the release of endogenous adrenocorticotrophic hormone (eACTH) by PI melanotrophs. To test this, plasma eACTH concentration was determined in horses with or without clinical signs of PPID at 0, 4, and 8 hours after oral administration of 3.3 mg domperidone/kg. Pituitary glands were evaluated postmortem by histologic grading and morphometry. In the 33 horses, median age, plasma ACTH concentration 8 hours after domperidone, and PI area in median sagittal sections were associated with histologic grade as follows: pituitary grade 1 (normal), n = 3, 7.5 years, 20.0 pg/ml, 0.16 cm2; grade 2 (focal hypertrophy or hyperplasia), n = 9, 14.5 years, 27.1 pg/ml, 0.27 cm2; grade 3 (diffuse adenomatous hyperplasia), n = 5, 21.0 years, 64.4 pg/ml, 0.48 cm2; grade 4 (microadenomas), n = 12, 23.3 years, 128.0 pg/ml, 0.87 cm2; grade 5 (adenoma), n = 4, 24.9 years, 720.5 pg/ml, 2.1 cm2. Results suggest that horses with pituitary histologic grade ≥3 respond to domperidone with increased plasma ACTH concentration.
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Affiliation(s)
- M. A. Miller
- Animal Disease Diagnostic Laboratory, Purdue University, West Lafayette, IN
- Departments of Comparative Pathobiology, Purdue University, West Lafayette, IN
| | - I. D. Pardo
- Animal Disease Diagnostic Laboratory, Purdue University, West Lafayette, IN
| | - L. P. Jackson
- Veterinary Clinical Sciences, Purdue University, West Lafayette, IN
| | - G. E. Moore
- Departments of Comparative Pathobiology, Purdue University, West Lafayette, IN
| | - J. E. Sojka
- Veterinary Clinical Sciences, Purdue University, West Lafayette, IN
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Evidence-based literature pertaining to thyroid dysfunction and Cushing's syndrome in the horse. Vet Clin North Am Equine Pract 2007; 23:329-64. [PMID: 17616317 DOI: 10.1016/j.cveq.2007.04.004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
The evidence-based literature pertaining to thyroid dysfunction and Cushing's syndrome is discussed in this article. Summaries of and recommendations for the treatment of these conditions are made. There is a need for reliable diagnostic tests for these conditions in horses.
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Aleman M, Watson JL, Williams DC, LeCouteur RA, Nieto JE, Shelton GD. Myopathy in horses with pituitary pars intermedia dysfunction (Cushing’s disease). Neuromuscul Disord 2006; 16:737-44. [PMID: 17005399 DOI: 10.1016/j.nmd.2006.07.019] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2006] [Revised: 06/29/2006] [Accepted: 07/14/2006] [Indexed: 11/26/2022]
Abstract
Fifteen horses with pituitary pars intermedia dysfunction were studied. The horses were of various breeds and between 15 and 28 years of age. Control horses matched for breed and age were studied for comparison. Evaluations included complete blood cell count and serum biochemical analysis, electromyography, and gluteus medius muscle biopsies for histochemical, morphometric, and ultrastructural analysis. No differences were found between groups of horses on routine laboratory analysis or electromyography. We demonstrated that muscle wasting in diseased horses was the result of atrophy of types 2A and 2B muscle fibers and loss of type 2B myofibers. Mild non-specific non-inflammatory myopathic alterations such as myofiber size variation, internal nuclei, perimysial, endomysial and sarcoplasmic fat accumulation were observed. At the ultrastructural level, subsarcolemmal mitochondrial accumulation and increased lipid droplets were evident. Similar to other species, this study confirmed atrophy of type 2 fibers as the cause of muscle mass loss in horses with Cushing's disease.
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Affiliation(s)
- M Aleman
- Department of Veterinary Medicine and Epidemiology, University of California, Davis, USA.
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Frank N, Andrews FM, Sommardahl CS, Eiler H, Rohrbach BW, Donnell RL. Evaluation of the Combined Dexamethasone Suppression/Thyrotropin-Releasing Hormone Stimulation Test for Detection of Pars Intermedia Pituitary Adenomas in Horses. J Vet Intern Med 2006. [DOI: 10.1111/j.1939-1676.2006.tb01816.x] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
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McFarlane D, Beech J, Cribb A. 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. Domest Anim Endocrinol 2006; 30:276-88. [PMID: 16115743 DOI: 10.1016/j.domaniend.2005.07.005] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/10/2005] [Revised: 07/12/2005] [Accepted: 07/23/2005] [Indexed: 11/19/2022]
Abstract
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 observed in horses likely differs. We proposed that TRH directly stimulates the PI in normal and PPID-affected horses to release proopiomelanocortin (POMC) derived peptides. Using alpha-melanocyte stimulating hormone (alpha-MSH) as a marker of a PI response and ACTH as a marker of a PD response, we were able to demonstrate a marked increase in plasma concentration of alpha-MSH and a modest, but significant increase in ACTH after TRH treatment in normal horses. The ability of TRH to directly stimulate release of POMC peptides was confirmed using PI and PD tissue explants. The presence of TRH receptor mRNA in PI tissue from both normal and PPID horses was confirmed using reverse transcriptase polymerase chain reaction. We conclude that TRH triggers the release of POMC-derived peptides from the PI through the direct stimulation of TRH receptors normally expressed on melanotropes. The increase in plasma cortisol following TRH in horses with PPID is likely attributable to the release of ACTH from the hyperplastic PI.
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Affiliation(s)
- Dianne McFarlane
- Atlantic Veterinary College, Department of Biomedical Sciences, 550 University Ave, Charlottetown, PE, Canada C1A 4P3.
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46
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McFarlane D, Miller LM, Craig LE, Dybdal NO, Habecker PL, Miller MA, Patterson JS, Cribb AE. Agreement in histologic assessments of the pituitary pars intermedia in aged horses. Am J Vet Res 2005; 66:2055-9. [PMID: 16379646 DOI: 10.2460/ajvr.2005.66.2055] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To evaluate concordance among veterinary pathologists in the assessment of histologic findings in the pars intermedia of pituitary gland sections from aged horses with mild signs suggestive of pituitary pars intermedia dysfunction (PPID). Sample Population-10 pituitary glands from aged horses. PROCEDURE 7 pathologists were provided with signalment, clinical signs, and a single H&E-stained pituitary gland section from 10 aged horses with mild signs suggestive of PPID. Pathologists described histologic findings for each section and stated whether findings were consistent with PPID. Agreement among pathologists and with antemortem diagnostic test results was calculated. RESULTS Overall, only fair agreement was found among the pathologists as to which horses had histologic findings consistent with disease (mean +/- SE kappa value, 0.34 +/- 0.069). Interpretation of individual sections varied, with minimal agreement (4 or 5/7 pathologists) for 5 of 10 sections evaluated. Postmortem assessment was in agreement with an antemortem endocrine diagnostic test result 79% of the time. CONCLUSIONS AND CLINICAL RELEVANCE Validation of antemortem diagnostic testing for PPID in horses often relies on the results of postmortem histologic evaluation. The lack of consensus in histologic interpretation of pituitary glands from aged horses with mild clinical signs in our study indicates that postmortem histologic evaluation of pituitary glands is an inappropriate standard in validation of antemortem diagnostic tests for detection of early PPID. Caution should be used when interpreting diagnostic test results in horses in which early PPID is suspected.
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Affiliation(s)
- Dianne McFarlane
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada
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McFarlane D, Cribb AE. Systemic and pituitary pars intermedia antioxidant capacity associated with pars intermedia oxidative stress and dysfunction in horses. Am J Vet Res 2005; 66:2065-72. [PMID: 16379648 DOI: 10.2460/ajvr.2005.66.2065] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To determine whether a deficiency in systemic or local (pars intermedia) antioxidant capacity is associated with pituitary pars intermedia oxidative stress and pituitary pars intermedia dysfunction (PPID) in horses. SAMPLE POPULATION Blood samples from 20 horses with PPID and 20 healthy client-owned horses, archived paraffin-embedded adrenal gland and substantia nigra tissues from 20 horses, and pituitary gland tissue from 16 horses. PROCEDURES Total glutathione, superoxide dismutase, and glutathione peroxidase activities were determined in RBCs. Accumulation of a systemic marker of oxidative stress (3-nitrotyrosine) was assessed in plasma and formalin-fixed, paraffin-embedded adrenal gland and substantia nigra tissues. Local antioxidants (total and manganese superoxide dismutase, glutathione peroxidase, and total glutathione) were measured in pars intermedia tissues. RESULTS No significant differences existed in systemic antioxidant enzyme activity or accumulation of 3-nitrotyrosine between horses with PPID and control horses. In pituitary gland tissues, glutathione peroxidase activity was increased in horses with oxidative stress, whereas total glutathione concentration and superoxide dismutase activity remained unchanged. There was an age-associated decrease in manganese superoxide dismutase activity in the pars intermedia. CONCLUSIONS AND CLINICAL RELEVANCE There was no evidence of systemic accumulation of oxidative stress markers or deficiencies in antioxidant capacity in horses with PPID, suggesting that these are unlikely to be major predisposing factors in the development of PPID. Manganese superoxide dismutase activity in the pars intermedia decreased significantly with increasing age. Role of an age-associated decrease in antioxidant capacity for the pars intermedia in the development of PPID in horses warrants further investigation.
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Affiliation(s)
- Dianne McFarlane
- Department of Biomedical Sciences, Atlantic Veterinary College, University of Prince Edward Island, Charlottetown, PE C1A 4P3, Canada
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