Acute environmental temperature variation affects brain protein expression, anxiety and explorative behavior in adult zebrafish.

This work investigates the effect of a 4-day acute thermal treatment at 18 °C, 26 °C (control) and 34 °C on the nervous system of adult zebrafish (<i>Danio rerio</i>) by a multidisciplinary approach based on behavioural test and brain proteomic analysis. The behavioural variations induced by the thermal treatment were investigated by means of five different tests (novel tank diving, light and dark preference, social preference, mirror biting, Y-Maze) which are paradigms used on zebrafish for assessing anxiety, boldness, social preference, aggressiveness, and explorative behaviour, respectively. Proteomic data revealed that several proteins involved in energy metabolism, translation, protein synthesis, folding and degradation, cytoskeleton organization and synaptic vesiculation are differently regulated at the extreme temperatures. The results showed increased anxiety-like behaviour and the down regulation of the expression of proteins belonging to anxiety-related signalling pathways in zebrafish at 18 °C compared to those at 26 °C and 34 °C. Moreover, the treatment both at 18 °C and 34 °C alters the exploratory behaviour that appears not to be modulated by past experiences suggesting an impairment of cognitive abilities. The present study follows our previous works in which the effect of a 21-day chronic treatment at the same temperatures was investigated using the same experimental design, allowing to compare the effect of acute and chronic treatment on the nervous system of adult zebrafish.