Document Type


Degree Name

Master of Science (MSc)




Faculty of Science

First Advisor

Linda Parker

Advisor Role

Thesis Supervisor


Recent evidence suggests that toxin-induced taste avoidance in the non-emetic rat is not mediated by conditioned sickness. In contrast, it appears that toxin-induced taste avoidance in an emetic species is mediated by conditioned sickness. The present experiments evaluated the potential of the anti-emetic agents, ondansetron [OND; a serotonin receptor (5-HT3) antagonist] and Delta(9)-tetrahydrocannabinol [THC; a cannabinoid (CB 1) agonist] to interfere with lithium chloride (LiCl)-induced taste avoidance in the house musk shrew (Suncus murinus). In Experiment 1, shrews were pretreated with OND (1.5 mg/kg) or saline 30 min prior to drinking 0.1% saccharin solution then they were injected with LiCl (390 mg/kg) or saline. When assessed by a two-bottle test over a 12 hr period, but not a one-bottle test, the shrews displayed a LiCl-induced saccharin avoidance that was prevented by pretreatment with OND. The relatively weak effects may have been due to floor effects in consumption of saccharin solution; therefore a highly preferred 0.3 M sucrose solution was used in Experiment 2. In Experiment 2, shrews were pretreated with OND, THC (5 and 10 mg/kg) or Vehicle 30 min prior to sucrose solution exposure. With a more highly preferred sucrose solution, OND and THC interfered with the establishment of LiCl-induced taste avoidance detected with one-bottle test. These results suggest that taste avoidance in the shrew, unlike the rat, is motivated by conditioned sickness.

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