Acute Effects of Fluoxetine on Stress Responses and Feeding Motivation in Nile Tilapia
Julia P. G. A. Miranda,
Ana Beatriz J. Isaac,
Rebeca B. Silva,
Leandro C. S. Toledo,
Leonardo J. G. Barcellos,
Helton Carlos Delicio,
Rodrigo Egydio Barreto
Affiliations
Julia P. G. A. Miranda
Department of Structural and Functional Biology (Physiology), Institute of Biosciences of Botucatu, Aquaculture Center of São Paulo State University—CAUNESP, UNESP, R. Prof. Dr. Antônio Celso Wagner Zanin, 250—Distrito de Rubião Junior, Botucatu 18618-689, SP, Brazil
Ana Beatriz J. Isaac
Department of Structural and Functional Biology (Physiology), Institute of Biosciences of Botucatu, Aquaculture Center of São Paulo State University—CAUNESP, UNESP, R. Prof. Dr. Antônio Celso Wagner Zanin, 250—Distrito de Rubião Junior, Botucatu 18618-689, SP, Brazil
Rebeca B. Silva
Department of Structural and Functional Biology (Physiology), Institute of Biosciences of Botucatu, Aquaculture Center of São Paulo State University—CAUNESP, UNESP, R. Prof. Dr. Antônio Celso Wagner Zanin, 250—Distrito de Rubião Junior, Botucatu 18618-689, SP, Brazil
Leandro C. S. Toledo
Department of Structural and Functional Biology (Physiology), Institute of Biosciences of Botucatu, Aquaculture Center of São Paulo State University—CAUNESP, UNESP, R. Prof. Dr. Antônio Celso Wagner Zanin, 250—Distrito de Rubião Junior, Botucatu 18618-689, SP, Brazil
Leonardo J. G. Barcellos
Programa de Pós-Graduação em Bioexperimentação, Universidade de Passo Fundo, BR 285, São José, Passo Fundo 99052-900, RS, Brazil
Helton Carlos Delicio
Department of Structural and Functional Biology (Physiology), Institute of Biosciences of Botucatu, Aquaculture Center of São Paulo State University—CAUNESP, UNESP, R. Prof. Dr. Antônio Celso Wagner Zanin, 250—Distrito de Rubião Junior, Botucatu 18618-689, SP, Brazil
Rodrigo Egydio Barreto
Department of Structural and Functional Biology (Physiology), Institute of Biosciences of Botucatu, Aquaculture Center of São Paulo State University—CAUNESP, UNESP, R. Prof. Dr. Antônio Celso Wagner Zanin, 250—Distrito de Rubião Junior, Botucatu 18618-689, SP, Brazil
The selective serotonin reuptake inhibitor fluoxetine is one of the most commonly administered psychotropic medications; however, it has been recognized as toxic to aquatic life. In this study, we showed that stress responses and feeding motivation in Nile tilapia were affected by acute exposure to fluoxetine. To reach that conclusion, we exposed Nile tilapia to 0, 1 or 10 µg/L (environmentally/biologically relevant doses) of fluoxetine over a 24 h period and then exposed them to a handling stressor. We found that the 10 µg/L dose enhanced cortisol response to stress but caused an earlier decrease in the ventilation boost induced by that stressor. An immediate ventilation boost after stressful stimuli indicates sympathetic activation. Thus, this suggests that fluoxetine decreased sympathetic nervous system activity but augmented hypothalamus–pituitary–interrenal axis activity in the fish. Both feeding latency and ingestion were similar among the tested conditions; however, a multiple logistic regression model revealed that in the presence of a stressor or fluoxetine, the Nile tilapia tended to ingest less food but there was a higher probability of this decrease to be associated with fluoxetine. We concluded that acute exposure to environmentally/biologically relevant fluoxetine concentrations over 24 h acted as a modifying factor for Nile tilapia stress physiology and tended to interfere with feeding motivation. An acute stress response is an emergency reaction that contributes to the recovery of homeostasis. In the presence of fluoxetine, modifications of acute stress responses and the tendency to reduce food intake, which restricts the ability to replace the energy spent on stress responses, could compromise the resumption of homeostasis and an animal’s adjustment to different environmental contexts, such as those associated with aquaculture, in which anthropogenic stressors inevitably occur.
