Fluoxetine and Curcumin Prevent the Alterations in Locomotor and Exploratory Activities and Social Interaction Elicited by Immunoinflammatory Activation in Zebrafish: Involvement of BDNF and Proinflammatory Cytokines

The increase in proinflammatory cytokine expression causes behavioral changes consistent with sickness behavior, and this led to the suggestion that depression might be a psychoneuroimmunological phenomenon. Here, we evaluated the effects of the pretreatment with fluoxetine (10 mg/kg, i.p.) and curcumin (0.5 mg/kg, i.p.) on the immune response elicited by the inoculation of an Aeromonas hydrophila bacterin in zebrafish. Non-pretreated but A. hydrophila-inoculated and sham-inoculated groups of fish served as controls. The social preference, locomotor, exploratory activities, and cerebral expression of il1b, il6, tnfa, and bdnf mRNA were compared among the groups. Behavioral changes characteristic of sickness behavior and a significant increase in the expression of il1b and il6 cytokines were found in fish from the immunostimulated group. The behavioral alterations caused by the inflammatory process were different between males and females, which was coincident with the increased expression of cerebral BDNF. Fluoxetine and curcumin prevented the sickness behavior induced by A. hydrophila and the increased expression of proinflammatory cytokines. Our results point to the potential of zebrafish as a translational model in studies related to neuroinflammation and demonstrate for the first time the effects of fluoxetine and curcumin on zebrafish sickness behavior.