IBBEA   24401
INSTITUTO DE BIODIVERSIDAD Y BIOLOGIA EXPERIMENTAL Y APLICADA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Brain serotonin, stress, and agonistic behaviour outcome modulation in a cichlid fish fed with an L-tryptophan supplemented diet
Autor/es:
MORANDINI LEONEL; GUIMARAES MOREIRA R; MARTIN RAMALLO; SOMOZA GUSTAVO; HONJI RENATO; PANDOLFI MATIAS
Lugar:
Gotemburgo
Reunión:
Congreso; 8th International Symposium on Fish Endocrinology; 2016
Resumen:
Serotonin (5-HT) is a neurotransmitter and neuromodulator known to be associated with aggression, stress and reproduction, beyond others. This monoamine synthesis depends on the amino acid L-tryptophan (trp), and so, brain 5-HT levels can be indirectly augmented by incorporating trp in the diet. In a first study we evaluate the effects of a 4 week trp-supplemented diet (TRP) on brain serotonergic activity, and cortisol and sex steroid hormone plasma levels in isolated specimens of the highly social cichlid fish Cichlasoma dimerus. Results showed that animals fed with TRP exhibited 1.6 times higher forebrain serotonergic activity and a 3.3 times higher reduction in their relative cortisol levels, with no effects on sex steroid plasma levels. Given that the dietary protocol succeeded in producing changes on brain serotonin, and considering its known relationship with aggression, we secondly focused on the possible effects of the aforementioned diet delivered for 2 weeks on the outcome of 1 hour male dyadic agonistic encounters, and the resultant hormonal profiles. Even though the winner of the contest was always the largest male, independently on the feeding protocol, results showed an increase in the latency to the first attack when at least one of the two males had received a TRP diet, and a higher number of total aggressive displays in the same condition. However, these increase consisted in a higher frequency of non-contact (threatening) displays, with a concomitant reduction of contact ones. At the hormonal level, testosterone and 17β-estradiol plasma concentrations did not differ between feeding conditions or among winners and losers. On the other hand, 11-ketotestosterone plasma levels were 4.5 times higher in winners than losers, independently of the diets. Finally, cortisol levels were always higher in fish that lost, and lower in those winners fed with TRP, with respect to winners fed with a non-enriched diet. These results indicate an effect of trp in the diet on brain serotonin, which probably results in the modulation of the stress response and the development of an agonistic encounter.