Effect of an osmotic stimulus on the secretion of arginine vasopressin and adrenocorticotropin in the horse.
Abstract: Arginine vasopressin (AVP) is released in response to changes in blood osmolality and is also a putative secretagogue for ACTH. However, it is unclear whether osmotically generated increases in AVP in the physiological range influence ACTH secretion. We have studied this question using our unique noninvasive technique for collecting pituitary venous blood in six normal conscious horses that received an iv infusion of hypertonic saline (HS; 5%, 0.07 ml/kg.min) for 45-60 min. Pituitary and jugular venous samples were collected every 5 min for 40 min before, during, and for 20 min after HS. During HS, mean blood osmolality rose (P less than 0.01), with a mean peak increase of 14.8 mosmol/kg (range, +6-+37 mosmol/kg). Jugular AVP rose (P less than 0.01) from 0.56 +/- 0.18 pmol/liter (mean +/- SEM) before HS to 2.16 +/- 0.86 pmol/liter during HS. Mean jugular AVP and osmolality were correlated (r = 0.82; P less than 0.05) during HS. Mean jugular ACTH concentrations increased (P less than 0.01) from 49 +/- 9 ng/liter before HS to 148 +/- 54 ng/liter during HS, while mean cortisol levels during and after HS exceeded basal levels (P less than 0.05). Pituitary AVP and ACTH concentrations exceeded jugular concentrations by up to 100-fold, and mean (P less than 0.01 for both) and peak (P less than 0.001 for both) levels increased during HS. AVP and ACTH secretion during HS were pulsatile. The mean and peak changes in pituitary AVP were significantly correlated with those in ACTH. For the six horses together, pituitary ACTH and AVP concentration changes occurred synchronously during the experiment (P less than 0.001), and the paired AVP and ACTH concentrations were highly correlated (r = 0.73; n = 129 pairs; P less than 0.001). We conclude that 1) physiological changes in AVP secretion are closely associated with comparable changes in ACTH secretion, and 2) osmotic signals that presumably activate the magnocellular neurons of the supraoptic and paraventricular nuclei may be physiologically relevant regulators of corticotrope function.
Publication Date: 1989-06-01 PubMed ID: 2542009DOI: 10.1210/endo-124-6-3102Google Scholar: Lookup
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- Journal Article
- Research Support
- Non-U.S. Gov't
- Research Support
- U.S. Gov't
- P.H.S.
Summary
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The research examines the correlation between the release of Arginine vasopressin (AVP) and Adrenocorticotropic hormone (ACTH) in horses, triggered by changes in blood osmolality. It suggests that osmotic variations that stimulate neurons in certain parts of the brain may be significant regulators of cortisol-secreting cells.
Research Methodology
- The researchers used a unique non-invasive technique to collect pituitary venous blood from six healthy conscious horses.
- These horses were given an intravenous infusion of hypertonic saline for a period of 45-60 minutes.
- Pituitary and jugular venous samples were collected every 5 minutes for 40 minutes prior to, during, and 20 minutes after the hypertonic saline treatment.
Measuring Changes in Blood Osmolality, AVP, and ACTH
- Throughout the hypertonic saline infusion, the average osmolality in the horse’s blood increased, peaking at an increase of 14.8 mosmol/kg.
- There was a marked increase in jugular AVP from 0.56 +/- 0.18 pmol/liter before the infusion to 2.16 +/- 0.86 pmol/liter during the infusion. A positive correlation between jugular AVP and osmolality was noted.
- Jugular ACTH concentrations also increased from 49 +/- 9 ng/liter to 148 +/- 54 ng/liter, while mean cortisol levels were higher than basal levels during and post infusion.
Greater Concentration of AVP and ACTH in Pituitary Blood
- In comparison to jugular concentrations, Pituitary AVP and ACTH concentrations were up to 100 times higher.
- Both mean and peak levels of these hormones increased notably during hypertonic saline infusion.
- The secretion of AVP and ACTH during the infusion process was pulsatile, with significant correlation identified between the mean and peak changes in pituitary AVP and ACTH.
Conclusion
- The research concludes that physiological changes in AVP secretion correspond closely with comparable changes in ACTH secretion.
- Furthermore, it suggests that osmotic signals that presumably activate the magnocellular neurons of the supraoptic and paraventricular nuclei may be significant in regulating corticotrope function.
Cite This Article
APA
Irvine CH, Alexander SL, Donald RA.
(1989).
Effect of an osmotic stimulus on the secretion of arginine vasopressin and adrenocorticotropin in the horse.
Endocrinology, 124(6), 3102-3108.
https://doi.org/10.1210/endo-124-6-3102 Publication
Researcher Affiliations
- Department of Animal and Veterinary Science, Lincoln College, Christchurch, New Zealand.
MeSH Terms
- Adrenocorticotropic Hormone / blood
- Adrenocorticotropic Hormone / metabolism
- Animals
- Arginine Vasopressin / blood
- Arginine Vasopressin / metabolism
- Female
- Horses / physiology
- Male
- Orchiectomy
- Reference Values
- Saline Solution, Hypertonic
- Water-Electrolyte Balance
Grant Funding
- DK-38322 / NIDDK NIH HHS
Citations
This article has been cited 6 times.- Elder E, Wong D, Johnson K, Robertson H, Marner M, Dembek K. Assessment of the hypothalamic-pituitary-adrenocortical axis function using a vasopressin stimulation test in neonatal foals.. J Vet Intern Med 2023 Sep-Oct;37(5):1881-1888.
- Ohbuchi T, Haam J, Tasker JG. Regulation of Neuronal Activity in Hypothalamic Vasopressin Neurons.. Interdiscip Inf Sci 2015;21(3):225-234.
- Polito A, Sonneville R, Guidoux C, Barrett L, Viltart O, Mattot V, Siami S, Lorin de la Grandmaison G, Chrétien F, Singer M, Gray F, Annane D, Brouland JP, Sharshar T. Changes in CRH and ACTH synthesis during experimental and human septic shock.. PLoS One 2011;6(11):e25905.
- Zaretsky DV, Molosh AI, Zaretskaia MV, Rusyniak DE, DiMicco JA. Increase in plasma ACTH induced by urethane is not a consequence of hyperosmolality.. Neurosci Lett 2010 Jul 19;479(1):10-2.
- Chen J, Young S, Subburaju S, Sheppard J, Kiss A, Atkinson H, Wood S, Lightman S, Serradeil-Le Gal C, Aguilera G. Vasopressin does not mediate hypersensitivity of the hypothalamic pituitary adrenal axis during chronic stress.. Ann N Y Acad Sci 2008 Dec;1148:349-59.
- Krause EG, Melhorn SJ, Davis JF, Scott KA, Ma LY, de Kloet AD, Benoit SC, Woods SC, Sakai RR. Angiotensin type 1 receptors in the subfornical organ mediate the drinking and hypothalamic-pituitary-adrenal response to systemic isoproterenol.. Endocrinology 2008 Dec;149(12):6416-24.
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