It has been centuries since humans consume coffee and get the benefits of this bean. Many researches worldwide continue to show healthful properties of coffee, while others suggest a number of side effects. In fact, anything consumed in excess may cause disturbance of the body functioning, whereas caffeine is a central nervous system stimulant that increases focus and improves performance, its high concentration can cause insomnia, dizziness, and vomiting. Thus, the question is: which coffee dose promotes benefits and prevents risks? To answer it, we used the zebrafish, a popular animal model that is at the vanguard of psychopharmacological research due to its unique combination of complexity and simplicity, translational relevance and applicability to high throughput behavioral drug screens. In the current study, we examine time-course and dose-dependent changes in zebrafish following exposure to caffeine. Our data show an inverted U-shaped path for the locomotor parameters and crescent path for the anxiety-like parameters. High doses are harmful to the individual, because the stimulating effect disappears and anxiogenic effects take place. We conclude that temporal analysis of zebrafish behavior is a sensitive method for the study of acute caffeine exposure-induced functional changes in the vertebrate brain.

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.

In this study we investigated the ability of zebrafish to discriminate visual signs and associate them with a reward in an associative-learning protocol including distractors. Moreover, we studied the effects of caffeine on animal performance in the task. After being trained to associate a specific image pattern with a reward (food) in the presence of other, distractor images, the fish were challenged to locate the exact cue associated with the reward. The distractors were same-colored pattern images similar to the target. Both the target and distractors were continually moved around the tank. Fish were exposed to three caffeine concentrations for 14 days: 0 mg/L (control, n = 12), 10 mg/L (n = 14), and 50 mg/L (n = 14). Zebrafish spent most of the time close to the target (where the reward was offered) under the effects of 0 and 10 mg/L caffeine, and the shortest latency to reach the target was observed for the 10-mg/L caffeine group. Both caffeine treatments (10 and 50 mg/L) increased the average speed and distance traveled when compared to the control group. This study confirms previous results showing that zebrafish demonstrate conditioned learning ability; however, low-dose caffeine exposure seems to favor visual cue discrimination and to increase zebrafish performance in a multicue discrimination task, in which primarily focus and attention are required in order to obtain the reward.Caffeine is one of the most consumed stimulants in the world (Ferré, 2008;Lieberman, 1992). It is present in a wide range of products, including coffee, energy drinks, teas, and chocolate. The popularity of this substance lies in its beneficial effects, such as heightened attention and alertness and decreased fatigue