Response of the adrenal cortex to tetracosactrin (ACTH1-24) in the premature and full-term foal.
Abstract: The changes in plasma cortisol concentration in the immediate postnatal period were examined in 3 groups of newborn foals and the response of the adrenal cortex to exogenous ACTH1-24 (tetracosactrin) was tested in 2 of these groups. In full-term Thoroughbred and Pony foals a rise in plasma cortisol occurred between 0 and 30 min after birth, whereas no significant cortisol changes could be detected within 2 h of birth in the group of prematurely delivered foals. These differences in plasma cortisol between term and premature foals were accompanied by differences in blood pH and lymphocyte and neutrophil counts. The high cortisol concentrations in the term animals declined to low levels by 4-12 h after birth. There was also a clear distinction between the responsiveness of the adrenal cortex to ACTH in the term and premature animals. When short-acting tetracosactrin was given as a single i.m. injection (0.125 mg), a rapid rise in plasma cortisol occurred in all term foals whereas no response was detected in the premature group during the same 2-h test period. The adrenal cortical response was also accompanied by a significant fall in the neutrophil/lymphocyte ratio at 2 h after the injection; no such change was seen in the premature animals. After a 24-h period of treatment with depot tetracosactrin (3 doses; 0.4, 0.2, 0.2 mg i.m.), a 2nd test with short-acting tetracosactrin led to a rise in plasma cortisol in term and pre-term foals during the 2-h test period. The depot tetracosactrin also appeared to cause a 3-fold increase in basal plasma cortisol levels in both groups.
Publication Date: 1982-01-01 PubMed ID: 6300391
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- Journal Article
- Research Support
- Non-U.S. Gov't
Summary
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This research studies how the hormone cortisol changes in newborn horses after birth and how the adrenal gland, which produces cortisol, responds to an artificial hormone stimulus. The results show significant differences in cortisol levels and adrenal responses between full-term and prematurely delivered foals.
Research Method
- The researchers looked at plasma cortisol concentration changes in three groups of newborn foals. These groups were made up of full-term Thoroughbred foals, full-term Pony foals, and prematurely delivered foals.
- This study also examined how the adrenal cortex responded to exogenous ACTH1-24 (tetracosactrin) in two of these groups.
Findings
- In full-term Thoroughbred and Pony foals, plasma cortisol levels rose between birth and 30 minutes after birth. In comparison, in prematurely delivered foals, no significant cortisol changes could be detected within two hours of birth.
- There were also differences in blood pH and lymphocyte and neutrophil counts between term and premature foals, accompanying the cortisol differences.
- The high cortisol levels in full-term animals decreased to low levels between 4 and 12 hours after birth.
- The adrenal cortex’s ability to respond to ACTH in full-term and premature foals was distinctly different. After a single injection of tetracosactrin, cortisol levels in full-term foals increased while no response was detected in the premature foals during the same period.
- However, after a 24-hour treatment with depot tetracosactrin, both full-term and pre-term foals showed an increase in cortisol response. Depot tetracosactrin also seemed to cause a three-fold increase in basal plasma cortisol levels in both groups.
Implications
- Developing an understanding of hormone regulation in newborn animals, particularly horses, can improve animal breeding practices and clinical care. Knowing how cortisol, a crucial stress hormone, changes in the early hours after birth can offer insights into the physiological stress the animal is experiencing and how best to support them.
- The results of this study suggest that premature foals might have a different stress response or a less developed adrenal system than full-term foals, which might require veterinarians to adjust their care strategies for premature foals.
- There is a need for further study to fully understand why the adrenal response differs between full-term and premature foals and how to best support premature foals’ physiological adjustment post-birth.
Cite This Article
APA
Rossdale PD, Silver M, Ellis L, Frauenfelder H.
(1982).
Response of the adrenal cortex to tetracosactrin (ACTH1-24) in the premature and full-term foal.
J Reprod Fertil Suppl, 32, 545-553.
Publication
Researcher Affiliations
MeSH Terms
- Adrenal Cortex / drug effects
- Adrenal Cortex / growth & development
- Adrenal Cortex / physiology
- Adrenocorticotropic Hormone / analogs & derivatives
- Aging
- Animals
- Animals, Newborn
- Cosyntropin / pharmacology
- Delivery, Obstetric
- Female
- Horses
- Hydrocortisone / blood
- Pregnancy
Citations
This article has been cited 6 times.- Wong DM, Vo DT, Alcott CJ, Stewart AJ, Peterson AD, Sponseller BA, Hsu WH. Adrenocorticotropic hormone stimulation tests in healthy foals from birth to 12 weeks of age. Can J Vet Res 2009 Jan;73(1):65-72.
- O'Connor SJ, Ousey JC, Gardner DS, Fowden AL, Giussani DA. Development of baroreflex function and hind limb vascular reactivity in the horse fetus. J Physiol 2006 Apr 1;572(Pt 1):155-64.
- O'Connor SJ, Gardner DS, Ousey JC, Holdstock N, Rossdale P, Edwards CM, Fowden AL, Giussani DA. Development of baroreflex and endocrine responses to hypotensive stress in newborn foals and lambs. Pflugers Arch 2005 Aug;450(5):298-306.
- Giussani DA, Forhead AJ, Fowden AL. Development of cardiovascular function in the horse fetus. J Physiol 2005 Jun 15;565(Pt 3):1019-30.
- Giussani DA, Forhead AJ, Gardner DS, Fletcher AJ, Allen WR, Fowden AL. Postnatal cardiovascular function after manipulation of fetal growth by embryo transfer in the horse. J Physiol 2003 Feb 15;547(Pt 1):67-76.
- Carrick JB, Papich MG, Middleton DM, Naylor JM, Townsend HG. Clinical and pathological effects of flunixin meglumine administration to neonatal foals. Can J Vet Res 1989 Apr;53(2):195-201.
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