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Effect of a territorial challenge on the steroid profile of a juvenile songbird Gray, Sofia L.

Abstract

Adult male song sparrows (Melospiza melodia) display territorial aggression year-round. Territoriality is supported by gonadal sex steroids during the breeding season but might be supported by brain-derived sex steroids during the non-breeding season. Juvenile (hatch-year) male song sparrows also defend territories during the non-breeding season despite having immature testes and low plasma testosterone levels. Juvenile males therefore represent an excellent model to investigate the modulatory role of neurosteroids on aggression. Here, free-living non-breeding juvenile males experienced a 10-min simulated territorial intrusion (STI) or control condition. Blood and brain were collected, and steroids were quantified in blood and microdissected brain regions via liquid chromatography-tandem mass spectrometry (LC-MS/MS). Juveniles were robustly aggressive during an STI. Juveniles were equally as aggressive or more aggressive than non-breeding adults. Androgens and estrogens were low or non-detectable in blood and brain regardless of social context. After an STI, progesterone and glucocorticoids were elevated in the blood and brain in a region-specific manner. Together, these data suggest that juvenile non-breeding aggression might be rapidly modulated by adrenal-derived or brain-derived progestogens and glucocorticoids. These rapid changes in steroid levels might impact behaviourally relevant neural circuits and mobilize energy stores from peripheral organs. To our knowledge, we are the first to investigate the interplay between developmental life-stage and social context at the behavioural and steroidal level in an avian model. This work provides insight into distinct endocrine and neuroendocrine mechanisms of social behaviour in a juvenile songbird that might extend to other vertebrates.

Item Metadata

Title
Effect of a territorial challenge on the steroid profile of a juvenile songbird
Creator
Gray, Sofia L.
Supervisor
Soma, Kiran Kumar
Publisher
University of British Columbia
Date Issued
2022
Description
Adult male song sparrows (Melospiza melodia) display territorial aggression year-round. Territoriality is supported by gonadal sex steroids during the breeding season but might be supported by brain-derived sex steroids during the non-breeding season. Juvenile (hatch-year) male song sparrows also defend territories during the non-breeding season despite having immature testes and low plasma testosterone levels. Juvenile males therefore represent an excellent model to investigate the modulatory role of neurosteroids on aggression. Here, free-living non-breeding juvenile males experienced a 10-min simulated territorial intrusion (STI) or control condition. Blood and brain were collected, and steroids were quantified in blood and microdissected brain regions via liquid chromatography-tandem mass spectrometry (LC-MS/MS). Juveniles were robustly aggressive during an STI. Juveniles were equally as aggressive or more aggressive than non-breeding adults. Androgens and estrogens were low or non-detectable in blood and brain regardless of social context. After an STI, progesterone and glucocorticoids were elevated in the blood and brain in a region-specific manner. Together, these data suggest that juvenile non-breeding aggression might be rapidly modulated by adrenal-derived or brain-derived progestogens and glucocorticoids. These rapid changes in steroid levels might impact behaviourally relevant neural circuits and mobilize energy stores from peripheral organs. To our knowledge, we are the first to investigate the interplay between developmental life-stage and social context at the behavioural and steroidal level in an avian model. This work provides insight into distinct endocrine and neuroendocrine mechanisms of social behaviour in a juvenile songbird that might extend to other vertebrates.
Genre
Thesis/Dissertation
Type
Text
Language
eng
Date Available
2022-08-12
Provider
Vancouver : University of British Columbia Library
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International
DOI
10.14288/1.0417298
URI
http://hdl.handle.net/2429/82341
Degree
Master of Arts - MA
Program
Psychology
Affiliation
Arts, Faculty of; Psychology, Department of
Degree Grantor
University of British Columbia
Graduation Date
2022-11
Campus
UBCV
Scholarly Level
Graduate
Rights URI
http://creativecommons.org/licenses/by-nc-nd/4.0/
Aggregated Source Repository
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Attribution-NonCommercial-NoDerivatives 4.0 International