title: Serotonergic outcome, stress and sexual steroid hormones, and growth in a South American cichlid fish fed with an L-tryptophan enriched diet.
abstract: Reared animals for edible or ornamental purposes are frequently exposed to high aggression and stressful situations. These factors generally arise from conspecifics in densely breeding conditions. In vertebrates, serotonin (5-HT) has been postulated as a key neuromodulator and neurotransmitter involved in aggression and stress. The essential amino acid L-tryptophan (trp) is crucial for the synthesis of 5-HT, and so, leaves a gateway for indirectly augmenting brain 5-HT levels by means of a trp-enriched diet. The cichlid fish Cichlasoma dimerus, locally known as chanchita, is an autochthonous, potentially ornamental species and a fruitful laboratory model which behavior and reproduction has been studied over the last 15years. It presents complex social hierarchies, and great asymmetries between subordinate and dominant animals in respect to aggression, stress, and reproductive chance. The first aim of this work was to perform a morphological description of chanchita's brain serotonergic system, in both males and females. Then, we evaluated the effects of a trp-supplemented diet, given during 4weeks, on brain serotonergic activity, stress and sexual steroid hormones, and growth in isolated specimens. Results showed that chanchita's brain serotonergic system is composed of several populations of neurons located in three main areas: pretectum, hypothalamus and raphe, with no clear differences between males and females at a morphological level. Animals fed with trp-enriched diets exhibited higher forebrain serotonergic activity and a significant reduction in their relative cortisol levels, with no effects on sexual steroid plasma levels or growth parameters. Thus, this study points to food trp enrichment as a "neurodietary'' method for elevating brain serotonergic activity and decreasing stress, without affecting growth or sex steroid hormone levels.
authors.affiliation: Laboratorio de Neuroendocrinología y Comportamiento, DBBE e IBBEA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Intendente Güirlades 2160, C1428EHA Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Leonel
authors.initials: L
authors.lastname: Morandini
authors.affiliation: Laboratorio de Neuroendocrinología y Comportamiento, DBBE e IBBEA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Intendente Güirlades 2160, C1428EHA Ciudad Autónoma de Buenos Aires, Argentina.
authors.forename: Martín Roberto
authors.initials: MR
authors.lastname: Ramallo
authors.affiliation: Departamento de Fisiologia, Instituto de Biociências-USP, Rua do Matão, travessa 14, n.321, sala 220 CidadeUniversitária, São Paulo, Brazil.
authors.forename: Renata Guimarães
authors.initials: RG
authors.lastname: Moreira
authors.affiliation: Departamento de Farmacología, Facultad de Farmacia y Bioquímica, Universidad de Buenos Aires, Junín 956, (C1113AAD) Buenos Aires, Argentina.
authors.forename: Christian
authors.initials: C
authors.lastname: Höcht
authors.affiliation: IIB-INTECH (CONICET-UNSAM), Av. Intendente Marino km 8.2 (B 7130IWA) Chascomús, Buenos Aires, Argentina.
authors.forename: Gustavo Manuel
authors.initials: GM
authors.lastname: Somoza
authors.affiliation: Unidad Bases Neurales de la Conducta, Instituto de Investigaciones Biológicas Clemente Estable, Ministerio de Educación y Cultura, Avda. Italia 3318, 11600 Montevideo, Uruguay; Laboratorio de Neurociencias, Facultad de Ciencias, Universidad de la República, Iguá 4225, 11400 Montevideo, Uruguay.
authors.forename: Ana
authors.initials: A
authors.lastname: Silva
authors.affiliation: Laboratorio de Neuroendocrinología y Comportamiento, DBBE e IBBEA-CONICET, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Intendente Güirlades 2160, C1428EHA Ciudad Autónoma de Buenos Aires, Argentina. Electronic address: pandolfi@bg.fcen.uba.ar.
authors.forename: Matías
authors.initials: M
authors.lastname: Pandolfi
mesh_terms: D000374:Aggression / Q000187:drug effects; D000818:Animals; D001921:Brain / Q000378:metabolism*; D023681:Cichlids / Q000502:physiology*; D004032:Diet; D005260:Female; D012739:Gonadal Steroid Hormones / Q000378:metabolism*; D006608:Hierarchy, Social; D006854:Hydrocortisone / Q000097:blood; D007124:Immunoenzyme Techniques; D008297:Male; D012701:Serotonin / Q000378:metabolism*; D012725:Sexual Behavior / Q000187:drug effects; D014364:Tryptophan / Q000008:administration & dosage*
chemical_list: D012739:Gonadal Steroid Hormones; D012701:Serotonin; D014364:Tryptophan; D006854:Hydrocortisone
keywords: Cichlids; Serotonin; Steroid hormones; Stress; l-Tryptophan