INSTITUTO TECNOLOGICO DE CHASCOMUS
Unidad Ejecutora - UE
congresos y reuniones científicas
DIETARY L-TRYPTOPHAN MODULATES AGONISTIC BEHAVIOR IN MALE DYADIC ENCOUNTERS AND BRAIN SEROTONIN IN A SOUTHAMERICAN CICHLID FISH
GUSTAVO M. SOMOZA; MATÍAS PANDOLFI; LEONEL MORANDINI
Congreso; 11th International Symposium on the Reproductive Physiology of Fish.; 2018
IntroductionCertain neurotransmitters, such as serotonin (5-HT), seem to play a central role on agonistic behavior. We can take advantage of the fact that l-tryptophan (Trp) is a precursor of 5-HT, and indirectly manipulate brain concentrations of the latter neurotransmitter. Most researches on dietary Trp effects on fish agonistic behavior have focused on juvenile but not adult agonistic repertories. In the present work we set out to study agonistic behavior between adultmales of the South American cichlid fish Cichlasoma dimerus, in dyadic encounters held in a novel context after being or not fed during two weeks with a Trp enriched diet. We also registered the response of brain serotonergic system in four anatomical areas.MethodsDuring the first 3 days of isolation, we fed males with commercial pellets. For the following 14 days, they either continued with a control diet (CTL protocol) (n= 24) or received an 8 times supplemented Trp one (n= 24).Once the dietary period ended, both males were placed in a novel aquarium and video recorded (1 h) to evaluate their agonistic repertories. Three different combinations of dyads where tested: CTL/CTL (CC), CTL/TRP (CT), and TRP/TRP (TT) (n = 8 for each combination). At the end of video registrations, we immediately anesthetized both fish and euthanized them by decapitation. We rapidly dissected brains toposteriorly evaluate 5-HT and 5-HIAA (5-HT?s main metabolite) concentrations in four brain regions: telencephalon (Tel), preoptic area/hypothalamus (Poa/Hyp), optic tectum (Ot) and brainstem (Bs).Results and DiscussionMales within TT dyads took twice as long to perform the first attack with respect to CT and CC ones. The relative proportions of bites and passive copings were lower than expected (CC) for TT dyads. Regarding inter-individual behavior, TRP dominant males performed 3 times less bites, whereas subordinate males confronted to TRP males showed 2.5 times less passive copings. The diet had no clear effect on which male resulted to be DOM; instead, opponents? body size differences determined who resulted DOM and SUB. Regarding serotonergic outcomes, SUB males were characterized by higher [5-HIAA/5-HT] at their Ot. On the other hand, TRP fed males showed higher [5-HIAA/5-HT] at their Tel and Poa/Hyp.Conclusion: In the present research, we showed that dietary Trp reduced the motivation to attack, and modulated both aggressive and submissive behaviors, the latter of which have been generally unconsidered. In addition, Trp supplementation produced a switch on males? agonistic repertory. Modifications at the brain serotonergic accompanied these behavioral outcomes.