Electronic Thesis and Dissertation Repository


Master of Science




Kavaliers, Martin

2nd Supervisor

Ossenkopp, Klaus-Peter

Joint Supervisor


Autism spectrum disorders (ASD) are caused by genetic factors and a complex set of risk factors including early stressors and alterations in the gut microbiome. The present thesis investigated whether environmental stressors during early adolescence predisposes rats administered another stressor in later adolescence and adulthood to produce altered anxiety-like behaviours, startle response, and percent prepulse inhibition. The early adolescent stressors used in this study included repeated administration of a bacterial endotoxin, lipopolysaccharide (LPS), or a stressful predator cat odour exposure. In later adolescence and adulthood, rats were administered with a gut microbial by-product, propionic acid (PPA), and subsequently tested on behaviour. Repeated early adolescent LPS exposure induced long-term anxiety-like behaviours and elevated startle response in adulthood. Repeated early adolescent cat odour exposure induced long-term anxiogenic effects. PPA exposure decreased activity and percent prepulse inhibition. Combined LPS and PPA exposure induced additive effects on activity, while prior cat odour exposure potentiated PPA’s reduction of vertical activity. The results of this thesis are important in evaluating the complex set of risk factors involved in the development of ASD.

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