Stress During Early-Adolescence Reduces Rats’ Aggression and Increases Their Serotonin Fibre Density in Adulthood
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Authors
Dhamija, Prateek
Date
Type
thesis
Language
eng
Keyword
Psychology , Serotonin , Stress , Development , Adolescent , Adolescence , Anxiety , Animal-Model , 5-HT , Aggression
Alternative Title
Abstract
Stressful experiences during youth can lead to a maladaptive behaviour profile in adulthood, including an increase in anxiety and aggression-related behaviours in humans. Rats exposed to the intermittent physical stress (IPS) paradigm in early-adolescence (PD 22 – 34) have lasting increases in anxiety-related behaviour. Greater anxiety-related behaviours have been shown to be associated with greater aggression-related behaviours. Therefore, I hypothesized that stress during early-adolescence would also lead to increases in aggression. In addition, greater anxiety and aggression have been associated with altered serotonergic function in the prefrontal cortex and ventral hippocampus. However, it is unclear whether a similar mechanism accounts for the enduring impact of stress during adolescence on those responses. In this experiment, I examined if IPS during early-adolescence increased anxiety-related behaviour in the elevated plus-maze and shock-probe burying test, as well as increased aggressive behaviour in the resident intruder test. In addition, I determined if there were changes in serotonin fibre density in the prefrontal cortex and ventral hippocampus. Male Long Evans rats (N = 24) were randomly assigned to either the early-adolescent stress or no-stress control groups. Rats were exposed to IPS stress (involving foot-shock, water immersion and elevated platform exposure) during early-adolescence and tested in the elevated plus-maze, shock-probe burying test and resident intruder test in adulthood. At the end of behavioural testing, brain tissue was examined for serotonin fibre density in the regions of interest using immunohistochemistry. Animals exposed to early-adolescent stress did not display greater levels of anxiety; however, they did display lower levels of aggression and an increase in serotonin fibre density in the prefrontal cortex. These results support that early-adolescence is a period of vulnerability of emotional development and raise the possibility that the impact of stress in adolescence on aggression in later life depends on when the stressors were experienced.
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Copying and Preserving Your Thesis
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Queen's University's Thesis/Dissertation Non-Exclusive License for Deposit to QSpace and Library and Archives Canada
ProQuest PhD and Master's Theses International Dissemination Agreement
Intellectual Property Guidelines at Queen's University
Copying and Preserving Your Thesis
This publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.