Plasma cortisol in the horse, diurnal rhythm and effects of exogenous ACTH.
Abstract: Peripheral blood plasma Cortisol concentration and its diurnal variation was measured in 4 horses. Mean concentration of Cortisol during 24 hrs. was 42 ng/ml (s ± 20 ng/ml). Peak values occurred at 6 a.m. and the lowest values were observed at about 6 p.m. (mean 65 ng/ml and 20 ng/ml, respectively). Long-acting ACTH at a dose of 150 i.u. was given by intramuscular injection to the 4 horses. Peak Cortisol concentrations markedly exceeding the prestimulation level were obtained between 2 and 4 hrs. after injection. During the immediate 24 hrs. after these peaks, the mean Cortisol level was markedly lower and the cyclic variation out of phase with the basal diurnal pattern. After a gradual adjustment during the second postinjection day, no differences could be seen between the 2 patterns on day 3 after injection. Cortisolkoncentrationen i perifer blodplasma och dess dygnsvariation mättes på fyra hästar. Medelkoncentrationen av Cortisol under 24 timmar var 42 ng/ml (s 20 ng/ml). Högsta värdena uppmättes klockan 06 och lägsta omkring klockan 18 (medelvärden 65 ng/ml respektive 20 ng/ml). Vid i.m. injektion av 150 IE långtidsverkande ACTH erhölls maximala cortisolkoncentrationer efter 2 till 4 timmar hos de fyra hästarna. Under de följande 24 timmarna var cortisolnivåerna markant lägre och dygnsrytmen förskjuten i förhållande till det basala mönstret. Under andra dagen efter injektionen skedde en gradvis justering och tre dagar efter injektionen kunde inga skillnader mellan de båda mönstren påvisas.
Publication Date: 1979-01-01 PubMed ID: 220863PubMed Central: PMC8322868DOI: 10.1186/BF03546625Google Scholar: Lookup
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- Journal Article
Summary
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The research article examines the diurnal variations in plasma cortisol concentrations in horses and the effects of externally introduced ACTH.
Research Methods
- The researchers conducted their study on four horses. The main variable they measured was the cortisol concentration in the horses’ peripheral blood plasma.
- The measurement was taken every 24 hours to observe the diurnal variation – the changes that occur in a day-night cycle.
- Additionally, the horses were given a dose of long-acting ACTH (Adrenocorticotropic hormone), administered through intramuscular injection. The ACTH stimulates the adrenal glands to release cortisol, which allows studying the physiological response to increased ACTH levels.
Key Findings
- The average cortisol concentration over a 24-hour period was found to be 42 ng/ml.
- Peak cortisol levels were recorded at 6 a.m., with the lowest levels observed at about 6 p.m.
- After ACTH injection, peak cortisol concentration -significantly higher than the pre-stimulation level- was obtained between two to four hours post-injection.
- However, in the 24 hours immediately following the post-ACTH injection peaks, the average cortisol level was markedly lower, and the diurnal pattern was out of sync with the baseline diurnal pattern.
- Over the second day post-injection, a gradual adjustment occurred in the cortisol levels. By the third day after injection, no significant differences were observed between the post-ACTH injection and baseline diurnal patterns.
Implications of the Study
- This study contributes valuable insights into the diurnal rhythm of cortisol, a vital hormone involved in stress responses and metabolic functions, in horses.
- Understanding the variations can help design appropriate horse management strategies, especially around timings for feeding, exercise, and medication.
- The observations surrounding exogenous ACTH administration could inform clinical practices for treating conditions like Cushing’s disease in horses, where ACTH levels are often excessively high.
Cite This Article
APA
Larsson M, Edqvist LE, Ekman L, Persson S.
(1979).
Plasma cortisol in the horse, diurnal rhythm and effects of exogenous ACTH.
Acta Vet Scand, 20(1), 16-24.
https://doi.org/10.1186/BF03546625 Publication
Researcher Affiliations
MeSH Terms
- Adrenocorticotropic Hormone / pharmacology
- Animals
- Circadian Rhythm / drug effects
- Horses / blood
- Hydrocortisone / blood
- Male
References
This article includes 8 references
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Citations
This article has been cited 7 times.- Kikuchi M, Nagata SI, Ishige T, Minamijima Y, Hirota KI, Tozaki T, Kakoi H, Kizaki K. Evaluation of the effect of glucocorticoid treatment on adrenocortical functions by monitoring endogenous hydrocortisone in horses. J Vet Med Sci 2023 Jun 13;85(6):647-652.
- Moss A, Leise B, Hackett E. Stress response as a contributing factor in horses with laminitis. J Vet Sci 2023 Mar;24(2):e33.
- Padalino B, Davis GL, Raidal SL. Effects of transportation on gastric pH and gastric ulceration in mares. J Vet Intern Med 2020 Mar;34(2):922-932.
- Murphy BA, Martin AM, Furney P, Elliott JA. Absence of a serum melatonin rhythm under acutely extended darkness in the horse. J Circadian Rhythms 2011 May 10;9:3.
- Desmecht D, Linden A, Amory H, Art T, Lekeux P. Relationship of plasma lactate production to cortisol release following completion of different types of sporting events in horses. Vet Res Commun 1996;20(4):371-9.
- Arias-Esquivel AM, Moscoso E, Umaña D, Arguedas M, Solano D, Durán G, Gómez A, Gutiérrez JM, León G. Stress levels, hematological condition, and productivity of plasma-producing horses used for snake antivenom manufacture: A comparison of two industrial bleeding methods. Toxicon X 2024 Dec;24:100212.
- Kikuchi M, Ishige T, Minamijima Y, Hirota KI, Nagata SI, Tozaki T, Kakoi H, Ishiguro-Oonuma T, Kizaki K. Identification of Potential miRNA Biomarkers to Detect Hydrocortisone Administration in Horses. Int J Mol Sci 2023 Sep 25;24(19).
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