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Dynamic changes in adolescent endocannabinoid signaling in male rats : relevance to stress responsivity and emotional behaviour

University of British Columbia

Adolescence is a period characterized by many distinct physical, behavioural and neural changes during the transition from child- to adulthood. In particular, adolescent neural changes often confer greater plasticity and flexibility, yet with this period of fluidity also comes the potential for heightened vulnerability to external perturbations such as stress exposure or recreational drug use. There is substantial evidence to suggest that factors such as adolescent stress exposure have longer lasting and sometimes more deleterious effects on an organism than stress exposure during adulthood. Moreover, the adolescent neuroendocrine response to stress exposure is different from that of adults, suggesting that further maturation of the adolescent hypothalamic-pituitary-adrenal (HPA) axis is required. The endocannabinoid system is a potential candidate underlying these age-dependent differences given that it is an important regulator of the adult hypothalamic-pituitary-adrenal (HPA) axis and neuronal development. Therefore, three studies were conducted in male rats to examine this possibility. The results of these experiments suggest that there is divergent age-dependent endocannabinoid tone between adolescents and adults (Chapter 2), age-dependent endocannabinoid regulation of HPA axis stress responsivity (Chapter 3) and a moderate organizational role of adolescent cannabinoid receptor type 1 (CB₁R) activation on adult stress responsivity and emotionality (Chapter 4). Taken together, the emerging picture suggests that the endocannabinoid system mediates interactions between HPA axis stress responsivity, emotionality and maturational stage. These findings may also be particularly relevant to our understanding of the development of affective disorders and the risks of adolescent cannabis consumption on emotional health and stress responsivity.

Text

2015-04-28

Attribution-NonCommercial-NoDerivs 2.5 Canada

http://hdl.handle.net/2429/52972

Psychology

University of British Columbia

UBCV

http://creativecommons.org/licenses/by-nc-nd/2.5/ca/