CONICET | Buscador de Institutos y Recursos Humanos

Seekingof drugs is commonly evaluated in a specific environment for assessing drugpreference. However, cognitive strategies involved in drug seeking are mostlyunknown. To assess the strength of environmental cues that can be associatedwith nicotine in the zebrafish brain reward circuitry, we have designed hereina modified conditioned place preference (CPP) paradigm. This task was devisedto identify salient environmental cues relevant for strong nicotineenvironmentassociation and drug seeking induction. During test sessions, background colorsof the CPP tank chambers were shifted and preference for colors associated tonicotine was assessed. We have compared several tank designs and differentcompartment colors. Our findings indicated that zebrafish seeking behavior wasstrongly dependent on compartment color shades. Combination of red and yellowenvironments, which were preferred and avoided compartments, respectively, wasthe most effective design presenting the highest CPP-score. Interestingly,animals that stayed for longer periods in the environment conditioned tonicotine during a first testing interval were also able to follow thebackground color shade conditioned to nicotine to the other compartmentimmediately after background colors were relocated between compartments. Duringa second testing period, zebrafish also stayed for longer periods in thecolored compartment paired to nicotine during conditioning. These findingssuggest that under salient environmental conditions, zebrafish voluntarilyfollowed a shifting visual cue previously associated with nicotine delivery.Furthermore, our findings indicate that zebrafish exhibit spatial associativelearning and memory, which generates a repertoire of conspicuous locomotorbehaviors induced by nicotine preference in the CPP task.