Involvement of anxiety-like behaviors and brain oxidative stress in the chronic effects of alarm reaction in zebrafish populations

Aversive conditions elicit anxiety responses that prepare the organism to an eventual threat. Nonetheless, prolonged anxiety is a pathological condition associated with various neuropsychiatric disorders. Here, we evaluated whether the conspecific alarm substance (CAS), a chemical cue that elicits aversion, influences anxiety-like behaviors and modulates brain oxidative stress-related parameters in wild-type (WT) and leopard (leo) zebrafish following a repeated exposure protocol. CAS exposure was performed for 5min, once daily for 7 consecutive days. In the 8th day, animals were tested in the light/dark and novel tank tests and their brains were further dissected for biochemical analyses. CAS chronically induced anxiogenic-like states in WT and leo populations when their behaviors were analyzed in the light/dark and novel tank tests. CAS also increased catalase (CAT) and glutathione S-transferase (GST) activities, as well as non-protein thiol (NPSH) content in WT and leo, but only leo had increased thiobarbituric reactive substance (TBARS) levels in the brain. At baseline conditions, leo was more 'anxious' when compared to WT, displaying lower CAT activity and carbonylated protein (CP) levels. Overall, CAS chronically triggers anxiety-like behavior in zebrafish populations, which may be associated with changes in oxidative stress-related parameters. Furthermore, the use of different zebrafish populations may serve as an interesting tool in future research aiming to investigate the neurobehavioral bases of neuropsychiatric disorders in vertebrates.