Modulatory action of taurine on ethanol-induced aggressive behavior in zebrafish

•The influence of taurine on ethanol-induced aggression was assessed in zebrafish.•Taurine per se exerts a biphasic response on aggressive behavior.•Taurine enhances or prevents the aggression triggered by ethanol.•Different aggressive profiles were observed in the mirror-induced aggression test.•Aggression levels can be estimated by an aggressive index in zebrafish.

Alcohol is a potent agent for eliciting aggression in vertebrates. Taurine (TAU) is an amino sulfonic acid with pleiotropic actions on brain function. It is one of the most abundant molecules present in energy drinks frequently used as mixers for alcoholic beverages. However, the combined effects of TAU and ethanol (EtOH) on behavioral parameters such as aggression are poorly understood. Considering that zebrafish is a suitable vertebrate to assess agonistic behaviors using noninvasive protocols, we investigate whether TAU modulates EtOH-induced aggression in zebrafish using the mirror-induced aggression (MIA) test. Since body color can be altered by pharmacological agents and may be indicative of emotional state, we also evaluated the actions of EtOH and TAU on pigment response. Fish were acutely exposed to TAU (42, 150, and 400 mg/L), EtOH (0.25%), or cotreated with both molecules for 1 h and then placed in the test apparatus for 6 min. EtOH, TAU 42, TAU 400, TAU 42/EtOH and TAU 400/EtOH showed increased aggression, while 150 mg/L TAU only increased the latency to attack the mirror. This same concentration also prevented EtOH-induced aggression, suggesting that it antagonizes the effects of acute alcohol exposure. Representative ethograms revealed the existence of different aggressive patterns and our results were confirmed by an index used to estimate aggression in the MIA test. TAU did not alter pigment intensity, while EtOH and all cotreated groups presented a substantial increase in body color. Overall, these data show a biphasic effect of TAU on EtOH-induced aggression of zebrafish, which is not necessarily associated with changes in body color.