Endocrine responses to repeated adrenocorticotropic hormone administration in free-ranging elephant
Understanding the physiological response of marine mammals to anthropogenic stressors can inform marine ecosystem conservation strategies. Stress stimulates release of glucocorticoid (GC) hormones, which increase energy substrate availability while suppressing energy-intensive processes. Exposure to...
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ftunivpacificmsl:oai:scholarlycommons.pacific.edu:uop_etds-4126 2023-05-15T16:05:40+02:00 Endocrine responses to repeated adrenocorticotropic hormone administration in free-ranging elephant McCormley, Molly 2018-01-01T08:00:00Z application/pdf https://scholarlycommons.pacific.edu/uop_etds/3127 https://scholarlycommons.pacific.edu/cgi/viewcontent.cgi?article=4126&context=uop_etds unknown Scholarly Commons https://scholarlycommons.pacific.edu/uop_etds/3127 https://scholarlycommons.pacific.edu/cgi/viewcontent.cgi?article=4126&context=uop_etds University of the Pacific Theses and Dissertations Aldosterone HPA axis Marine Mammals Stress Thyroid biology text 2018 ftunivpacificmsl 2022-04-10T22:18:01Z Understanding the physiological response of marine mammals to anthropogenic stressors can inform marine ecosystem conservation strategies. Stress stimulates release 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 assess the endocrine response of a marine mammal to repeated stressors, we administered adrenocorticotropic hormone (ACTH) to free-ranging juvenile northern elephant seals (Mirounga angustirostris; n=7) once daily for four days. ACTH administration induced significant, but transient (<24 h) elevation in circulating cortisol levels (p < 0.0001). These increases did not vary in magnitude between the first ACTH challenge on day 1 and the last challenge on day 4. In contrast, aldosterone levels remained elevated above baseline for at least 24 hours after each ACTH injection (p < 0.001), and responses were greater on day 4 than day 1 (p < 0.01). Total triiodothyronine (tT3) levels were decreased on day 4 relative to day 1 (p < 0.01), while reverse triiodothyronine (rT3) concentrations increased relative to baseline on days 1 and 4 (p < 0.001) in response to ACTH, indicating a suppression of thyroid hormone secretion. There was no effect of ACTH on the sex steroid dehydroepiandrosterone (DHEA). These results suggest that elephant seals are able to mount adrenal responses to multiple ACTH challenges. However, repeated stress results in facilitation of aldosterone secretion and suppression of tT3, which may impact osmoregulation and metabolism. We propose that aldosterone and tT3 are informative additional indicators of repeated stress in marine mammals. Text Elephant Seals University of the Pacific, McGeorge School of Law: Scholarly Commons |
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University of the Pacific, McGeorge School of Law: Scholarly Commons |
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Aldosterone HPA axis Marine Mammals Stress Thyroid biology |
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Aldosterone HPA axis Marine Mammals Stress Thyroid biology McCormley, Molly Endocrine responses to repeated adrenocorticotropic hormone administration in free-ranging elephant |
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Aldosterone HPA axis Marine Mammals Stress Thyroid biology |
description |
Understanding the physiological response of marine mammals to anthropogenic stressors can inform marine ecosystem conservation strategies. Stress stimulates release 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 assess the endocrine response of a marine mammal to repeated stressors, we administered adrenocorticotropic hormone (ACTH) to free-ranging juvenile northern elephant seals (Mirounga angustirostris; n=7) once daily for four days. ACTH administration induced significant, but transient (<24 h) elevation in circulating cortisol levels (p < 0.0001). These increases did not vary in magnitude between the first ACTH challenge on day 1 and the last challenge on day 4. In contrast, aldosterone levels remained elevated above baseline for at least 24 hours after each ACTH injection (p < 0.001), and responses were greater on day 4 than day 1 (p < 0.01). Total triiodothyronine (tT3) levels were decreased on day 4 relative to day 1 (p < 0.01), while reverse triiodothyronine (rT3) concentrations increased relative to baseline on days 1 and 4 (p < 0.001) in response to ACTH, indicating a suppression of thyroid hormone secretion. There was no effect of ACTH on the sex steroid dehydroepiandrosterone (DHEA). These results suggest that elephant seals are able to mount adrenal responses to multiple ACTH challenges. However, repeated stress results in facilitation of aldosterone secretion and suppression of tT3, which may impact osmoregulation and metabolism. We propose that aldosterone and tT3 are informative additional indicators of repeated stress in marine mammals. |
format |
Text |
author |
McCormley, Molly |
author_facet |
McCormley, Molly |
author_sort |
McCormley, Molly |
title |
Endocrine responses to repeated adrenocorticotropic hormone administration in free-ranging elephant |
title_short |
Endocrine responses to repeated adrenocorticotropic hormone administration in free-ranging elephant |
title_full |
Endocrine responses to repeated adrenocorticotropic hormone administration in free-ranging elephant |
title_fullStr |
Endocrine responses to repeated adrenocorticotropic hormone administration in free-ranging elephant |
title_full_unstemmed |
Endocrine responses to repeated adrenocorticotropic hormone administration in free-ranging elephant |
title_sort |
endocrine responses to repeated adrenocorticotropic hormone administration in free-ranging elephant |
publisher |
Scholarly Commons |
publishDate |
2018 |
url |
https://scholarlycommons.pacific.edu/uop_etds/3127 https://scholarlycommons.pacific.edu/cgi/viewcontent.cgi?article=4126&context=uop_etds |
genre |
Elephant Seals |
genre_facet |
Elephant Seals |
op_source |
University of the Pacific Theses and Dissertations |
op_relation |
https://scholarlycommons.pacific.edu/uop_etds/3127 https://scholarlycommons.pacific.edu/cgi/viewcontent.cgi?article=4126&context=uop_etds |
_version_ |
1766401563710980096 |