Irish coffee: Effects of alcohol and caffeine on object discrimination in zebrafish

• We investigated alcohol and caffeine effects on objects discrimination in zebrafish.
• Acute alcohol dose, and alcohol and caffeine withdrawal impaired discrimination.
• Alcohol withdrawal in combination with acute caffeine allowed for discrimination.
• Moderate caffeine usage seems to ameliorate alcohol withdrawal syndrome.
• High caffeine usage seems to be highly deleterious during alcohol withdrawal.

Many studies regarding the effects of drugs investigate the acute and chronic use of alcohol, but only a few address the effects of caffeine and alcohol combined to the performance of the zebrafish in cognitive tasks. The zebrafish is an important model for studying the effects of drugs on learning, because it has large genetic similarities to humans and the non-invasive administration of the substances favors translational bias of research. In this study, we observed the effects of alcohol and caffeine on zebrafish cognition through an object discrimination test. We noticed that animals subjected to acute alcohol dose and those under alcohol or caffeine withdrawal did not show discrimination. When fish were treated with associated alcohol and caffeine, those chronically treated with alcohol and subjected to moderate acute dose of caffeine showed learning of the task. Our results reinforce the harmful effects of the alcohol use on cognitive tasks, and suggest that continued use of high doses of caffeine cause cognitive impairment during withdrawal of the substance. However, the acute use of caffeine appears to reverse the harmful effects of alcohol withdrawal, allowing discriminative performance equivalent to control fish. Finally, we reiterate the use of zebrafish as a model for drug effects screening and search for active compounds that modulate the alcohol and caffeine effects.