Master of Science (MSc)
Faculty of Science
Problem gambling is a widespread phenomenon with a prevalence estimate of 2.3% globally (Williams, Volberg, & Stevens, 2012). Although little is known about the neurochemistry underlying this pathological behaviour, evidence suggests that dysregulation of the brain’s endocannabinoid (eCB) system may be implicated in impulsivity and decision-making. For example, chronic cannabis users exhibit impulsive behaviour and impaired decision-making on the Iowa Gambling Task (IGT). The present study sought to further examine the role of the eCB system in problem gambling-related decision-making in laboratory rats using the five-choice serial reaction time task (5-CSRTT), and a recently-developed rodent analogue of the IGT called the rat gambling task (rGT). It was predicted that increasing neural levels of the eCB anandamide by administering the fatty acid amide hydrolase (FAAH) inhibitor URB597 would increase impulsivity as found previously with psychomotor stimulants. Results revealed that URB597 (0.03-1 mg/kg, IP) had no effect on premature responding or correct choices. Cocaine (15 mg/kg, IP) increased premature responding and decreased choice accuracy in the 5-CSRTT, but these effects were not attenuated by the CB1 inverse agonist rimonabant (3 mg/kg, IP). Furthermore, neither URB597 (0.03-1 mg/kg, IP) nor the cannabinoid receptor agonist THC (1.0-1.5 mg/kg, IP) altered optimal choice preference or premature responding in the rGT. Taken together, results did not support the notion that eCBs are involved in impulsivity or decision-making. We also conclude that any involvement of the eCB system in impulsivity is likely a downstream process from dopamine release.
Norris, Christopher P., "Endocannabinoid Involvement in Impulsivity and Decision-making" (2014). Theses and Dissertations (Comprehensive). 1676.