The antidepressant fluoxetine alters food intake in cichlid fish

DORELLE, LUCIANA; DA CUÑA, RODRIGO; REY VAZQUEZ, GRACIELA; GENOVESE, GRISELDA; LO NOSTRO, FABIANA L.

CABA

Congreso; SETAC Latin America 11th Biennial Meeting; 2015

SETAC

Pharmaceuticals are commonly used to improve human and animal healthcare. These compounds are known as ?emerging concern pollutants? since after their consumption and excretion, they reach freshwater bodies as wastewater treatment plants are incapable of removing them, and could therefore affect non-target organisms. Among antidepressants, SSRIs -Serotonin Selective Reuptake Inhibitors- are prescribed for several psychiatric disorders, such as obsessive-compulsive disorder and feeding alterations. In vertebrates, serotonin (5-HT) regulates behavior, humor, sexual impulse and appetite. Particularly, fluoxetine (FLX) is the active ingredient of one of the most consumed SSRIs worldwide, Prozac®. The main objective of this work was to evaluate the effect of FLX on the food intake rate in Cichlasoma dimerus, a South American freshwater fish who displays distinctive social hierarchies and agression patterns. Additionally, we analyzed the relationship between feeding, liver and brain serotonergic activity. Each fish received a daily intraperitoneal (i.p.) or intramuscular (i.m.) injection for 5 days of saline 0.6% (control group), 2 or 20 ug/g of FLX. Daily food intake was quantified throughout the experiment. At the end of the experiment, levels of 5-HT and its metabolite 5-HIAA were determined in brain using HPLC-EC as a measure of brain serotonergic activity. Livers were weighed, fixed and processed for histology. Slides were stained with Masson´s Trichromic and PAS techniques. Although no significant alterations were registered on brain serotonergic activity for neither i.p. nor i.m. experiments, a tendency towards a dose-dependent increase was observed for i.m. In groups injected with 20 ug/g of FLX a marked decrease on food intake was observed in both cases. This was associated with the presence of intense acidophilia, lack of lipid reserves and marked area reduction of hepatocytes. No alterations were observed in hepatosomatic index or body weight. These results may indicate that FLX is producing an anorexigenic effect in C. dimerus adults, hence it could impact over reproductive physiology and behavior of this species, considering that aggressive interactions and the establishment of social hierarchies are pivotal for reproductive success.