ENVIRONMENTAL INFLUENCES AND EPIGENETIC MECHANISMS IN RISK FOR DEPRESSION

Thesis (Ph.D, Psychology) -- Queen's University, 2016-10-04 17:37:07.888

Cold acclimation of chill coma mechanisms in the locust CNS

Temperature has profound effects on the neural function and behaviour of insects. When exposed to low temperature, migratory locusts (Locusta migratoria) enter chill coma (neuromuscular paralysis) and can resume normal body functions after returning to normal temperature. Our laboratory has studied phenomena underlying environmental stress-induced comas in locusts and found that they are associated with a sudden loss of K+ homeostasis and also a temporary electrical silence in the central nervous system (CNS). However, the mechanisms underlying chill coma entry and recovery are not well understood, particularly the role of the CNS has not been determined. Here, I investigated neural function during chill coma in the locust by measuring electrical activity in the CNS. As pre-exposure to moderately low temperatures, either chronically (cold acclimation) or acutely (rapid cold hardening; RCH), has been found to improve the insect’s cold tolerance, I also determined cold acclimation and RCH protocols that will improve the locust's cold tolerance and whether these protocols affect neural shutdown during chill coma in the locust. With an implanted thermocouple in the thorax, I determined the temperature associated with a loss of responsiveness (CTmin) in intact male adult locusts. In parallel experiments, I recorded field potential (FP) in the metathoracic ganglion (MTG) in semi-intact preparations to determine the temperature that would induce neural shutdown. I found that acclimation at 10 ˚C and RCH at 4 ˚C reduced chill coma recovery time (CCRT) in intact animal preparations and RCH at 4 ˚C for 4 hours reduced the temperature at neural shutdown in semi-intact preparations. These results suggest that pre-exposure to cold can improve the locust's resistance to chill coma and support the notion that the CNS has a role in determining entry into and exit from chill coma in locusts.

Operational Stress Injuries: Impact on Family Mental Health and Well-being

This study was part of a larger scoping review and environmental scan conducted for Veterans Affairs Canada on the effects of operational stress injuries (OSIs) on the mental health and wellbeing of Veterans’ families. This paper focuses broadly on the relationships between combat (and/or deployment more generally), OSIs (primarily post-traumatic stress disorder (PTSD)), and the family. Based on the scoping review, the paper finds that existing research investigates the impacts of a Veteran’s OSI on the family, but also how various aspects of the family (such as family functioning, family support, etc.) can impact a Veteran living with an OSI.