Document Type

Thesis

Degree Name

Master of Science (MSc)

Department

Psychology

Faculty/School

Faculty of Science

First Advisor

Rudy Eikelboom

Advisor Role

Thesis Supervisor

Abstract

Anorexia Nervosa (AN) is characterized by a self-imposed starvation and is often accompanied by excessive exercise that results in severe malnutrition and sometimes death. Behavioural and pharmacological treatments of AN need to be improved. In rats, acute 3 h daytime wheel access suppresses ad lib feeding over the subsequent night relative to no wheel controls, a phenomenon that has been suggested as an animal model of AN. This acute wheel induced feeding suppression (WIFS), can be induced reliably when rats are given limited wheel access exposure during the light cycle (Lattanzio & Eikelboom, 2003). The acute WIFS is useful because it can be used to test the effects of pharmacological agents, in a paradigm where the duration of wheel running and its effects are tightly defined. Chronic chlorpromazine injections can minimize the severity of activity anorexia (AA) procedure (Routtenberg, 1968), a related rat model of AN (Epling, Pierce & Stephan, 1983), by attenuating wheel running. Experiment 1 tested the acute effects of a one-time chlorpromazine injection (2 mg/kg IP) on the acute WIFS in 40 adult male rats. Animals were divided into five treatment groups (n=8): drug before wheel access (DW); drug after wheel access (WD); drug with locked wheel access (DNW); saline with locked wheel access (SNW); and saline with wheel access (SW). Half of each of the three control groups (DNW, SNW and SW) received injections before wheel access and half were injected after the wheel access period. Experiment 2 followed the same procedure except a broader range of chlorpromazine doses was tested (0.25, 0.50, 1 and 2 mg/kg). Both studies show that while chlorpromazine (at 1 and 2 mg/kg) did not attenuate feeding or wheel running, it blocked the acute WIFS. At doses of 0.25 and 0.50 mg/kg chlorpromazine had no effect. Because the pharmacological profile of chlorpromazine implicates the serotonin, histamine and dopamine systems in the acute WIFS (and potentially AN), future work should look at drugs with more specific modes of action to identify which neurotransmitter systems may be involved. The acute WIFS procedure may be useful for screening potential drug treatments for AN, where exercise is often elevated and feeding is suppressed.

Convocation Year

2010

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