The lasting influence of social stressors in adolescence on development

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Critical or sensitive periods of development are times in which the brain is undergoing a rapid rate of growth and is susceptible to a variety of environmental influences. Experiences such as exposure to stress and quality of social interactions during these periods can lead to relatively permanent effects on brain function. Although much research has shown prenatal and neonatal life to be sensitive periods of development, adolescence has received less attention by researchers. My lab has shown that adolescence is also be a time when ongoing development of the brain is shaped by stressors and social interactions. Our research to date has shown that mild social stress in adolescence leads to changes in hypothalamic-pituitary-adrenal function, increases risk for anxiety-like and depressive behaviour, and leads to lasting changes in behavioural responses to drugs of abuse. Importantly, the same social instability procedure administered in adulthood did not have the same effects as in adolescence, which highlights the significance of the ontogenetic stage of the animal in the effects of stressors. With this grant, we propose to investigate the neural basis for differences between adolescents and adults in drug-induced plasticity and the means by which stress confers risk on the developing brain in adolescence. We will use immunohistochemistry and western blot techniques to examine several markers of plasticity in neural regions implicated in drug effects. We also will characterize functional changes in the amygdala and hippocampus through the use of behavioural measures that rely on these neural structures, and to investigate mesolimbic system function using naturalistic reward in addition to drug-related reward. The proposed research will increase the understanding of adolescence as a time of sex-specific plasticity in brain development, and the role of environment in shaping individual differences in behaviour and brain function.