[MARMAM] New publication: Repeated adrenocorticotropic hormone administration alters adrenal and thyroid hormones in free-ranging elephant seals

Jane Khudyakov jkhudyakov at gmail.com
Tue Jul 17 12:54:38 PDT 2018


Dear MARMAM Colleagues,

My coauthors and I would like to announce the following publication:

McCormley MC, Champagne CD, Deyarmin JS, Stephan AP, Crocker DE, Houser DS,
Khudyakov JI. Repeated adrenocorticotropic hormone administration alters
adrenal and thyroid hormones in free-ranging elephant seals, Conservation
Physiology, Volume 6, Issue 1, 1 July 2018, coy040,
https://doi.org/10.1093/conphys/coy040

Abstract
Understanding the physiological response of marine mammals to anthropogenic
stressors can inform marine ecosystem conservation strategies. Stress
stimulates the activation of the hypothalamic–pituitary–adrenal (HPA) axis
and synthesis of glucocorticoid (GC) hormones, which increase energy
substrate availability while suppressing energy-intensive processes.
Exposure to repeated stressors can potentially affect an animal’s ability
to respond to and recover from subsequent challenges. To mimic repeated
activation of the HPA axis by environmental stressors (or challenges), we
administered adrenocorticotropic hormone (ACTH) to free-ranging juvenile
northern elephant seals (Mirounga angustirostris; n = 7) once daily for 4
days. ACTH administration induced significant elevation in circulating
cortisol and aldosterone levels. The cortisol responses did not vary in
magnitude between the first ACTH administration on Day 1 and the last
administration on Day 4. In contrast, aldosterone levels remained elevated
above baseline for at least 24 h after each ACTH injection, and responses
were greater on Day 4 than Day 1. Total triiodothyronine (tT3) levels were
decreased on Day 4 relative to Day 1, while reverse triiodothyronine (rT3)
concentrations increased relative to baseline on Days 1 and 4 in response
to ACTH, indicating a suppression of thyroid hormone production. There was
no effect of ACTH on the sex steroid dehydroepiandrosterone. These data
suggest that elephant seals are able to mount adrenal responses to multiple
ACTH administrations. However, repeated ACTH administration resulted in
facilitation of aldosterone secretion and suppression of tT3, which may
impact osmoregulation and metabolism, respectively. We propose that
aldosterone and tT3 are informative additional indicators of repeated
stress in marine mammals.

I am happy to provide a PDF of the article to those that cannot access it.

Sincerely,
Jane

---

Jane Khudyakov
Assistant Professor
Department of Biological Sciences
University of the Pacific
Stockton, CA 95211
jkhudyakov at pacific.edu
physgenlab.weebly.com
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