Document Type

Thesis

Degree Name

Master of Science (MSc)

Department

Psychology

Faculty/School

Faculty of Science

First Advisor

Paul Mallet

Advisor Role

Thesis Supervisor

Abstract

The selective cannabinoid CB1 receptor antagonist SR141716 has been shown to precipitate physical signs of withdrawal in ∆9-tetrahydrocannabinol (THC)-dependent rats; however, the affective state associated with this withdrawal state has not yet been well characterized. Thus, the aim of present study was to examine the physical and affective consequences of SR141716-precipitated THC withdrawal in male Sprague-Dawley rats. Rats were injected with THC (5 mg/kg, i.p.) or its vehicle twice daily for 13 consecutive days, and challenged with SRI 41716 (1 mg/kg, i.p.) or its vehicle 1 h later on days 3, 5, 7, 9, 11, and 13. Consistent with previous reports, SR141716 induced signs of physical withdrawal (e.g., increased scratching) in THC-dependent animals. The affective state induced by both SR141716-precipitated THC withdrawal and naloxoneprecipitated morphine withdrawal were then assessed using a tactile cue-conditioning paradigm, and withdrawal-induced anxiety was measured using a test battery consisting of the emergence test, elevated plus maze (EPM), and social interaction test. Precipitated morphine withdrawal induced both significant conditioned cue avoidance and anxiogenic-like behaviour; however, precipitated THC withdrawal failed to produce a conditioned cue avoidance, and did not induce anxiety in a manner different from that produced by administration of THC alone. These findings provide novel evidence that unlike opiate withdrawal, cannabinoid withdrawal manifests physical signs of withdrawal, but does not induce anxiety or a dysphoric state. Although there may be overt physical similarities between opiate and cannabinoid withdrawal, these syndromes likely represent distinct emotional and subjective states.

Convocation Year

2010

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