FROM THE MOUTH TO THE BRAIN AND BEYOND: AN L-TRYPTOPHAN-ENRICHED DIET MODULATES AGONISTIC BEHAVIOR AND NEUROENDOCRINE ACTIVITY IN A SOUTH AMERICAN CICHLID FISH

MARTÍN ROBERTO RAMALLO; MATÍAS PANDOLFI; GUSTAVO MANUEL SOMOZA; LEONEL MORANDINI

Montevideo

Congreso; XII Congress International Society of Neuroethology; 2016

L-Tryptophan (TRP) supplementation has been broadly implemented to investigate the role ofserotonin (5-HT) in varied physiological and behavioral processes. The heart of the matter lies in thefact that TRP is the precursor 5-HT biosynthesis. Therefore, variation in food TRP concentration isexpected to change 5-HT levels in the brain. The aim of this work was to evaluate the effects of twodiets with different TRP concentrations on stress and sexual steroid hormones, serotonergic activity,and agonistic behavior in the South American cichlid fish Cichlasoma dimerus. In an initial study,isolated specimens (males and females) were fed during 4 weeks with either of the diets. Animals fedwith enriched-TRP (+TRP) exhibited higher forebrain serotonergic activity and reduced cortisol plasmalevels, while sexual steroid plasma levels did not differ from those present with less TRP. In a secondexperiment, males were isolated for 2 weeks, receiving either of the aforementioned diets. Afterwards,pairs of males were placed in fighting arenas and agonistic interactions were recorded for one hour.Results showed that the total number of aggressive displays was lower and the latency to the firstattack was longer when both males had been fed with +TRP. Winner males always exhibited lowercortisol and higher 11-ketotestosterone plasma levels. In conclusion, dietary TRP supplementationsucceeded in modulating behavioral and neuroendocrine parameters, probably through changes inbrain 5-HT activity.