title: Effects of chronic administration of tryptophan with or without concomitant fluoxetine in depression-related and anxiety-like behaviors on adult rat.
abstract: Depression and anxiety play an important role in decreasing quality of life worldwide. Since tryptophan is a serotonin precursor and low levels of serotonin seems to be related to depression, the effect of oral tryptophan has been investigated for possible potentiation of the action of antidepressant drugs. We investigated the effects of chronically administered tryptophan (50mg/kg/day, p.o.) with or without concomitant fluoxetine (10mg/kg/day, s.c.) on adult rats regarding depression-related and anxiety-like behaviors. Tryptophan levels in cerebrospinal fluid (CSF) were measured 4h after a single administration of daily dosages of chronic treatments. We found that tryptophan increased depressive-related behavior, but did not alter anxiety-like behavior. However, fluoxetine decreased depression-related behavior and was anxiogenic. Tryptophan with concomitant fluoxetine did not alter anxiety-like behavior. Moreover, our data suggests that the antidepressant effect of fluoxetine was not enhanced by concomitant administration of tryptophan, which could be associated with increased levels of tryptophan in CSF. Further investigations are needed to elucidate the related mechanisms.
authors.affiliation: Department of Biochemistry, Institute of Basic Health Sciences, Federal University of Rio Grande do Sul, Porto Alegre, RS, Brazil. fernandahansen@hotmail.com
authors.forename: Fernanda
authors.initials: F
authors.lastname: Hansen
authors.forename: Diogo Losch
authors.initials: DL
authors.lastname: de Oliveira
authors.forename: Francieli Ubirajara Índia
authors.initials: FU
authors.lastname: Amaral
authors.forename: Fabiana Salvatori
authors.initials: FS
authors.lastname: Guedes
authors.forename: Tainá July
authors.initials: TJ
authors.lastname: Schneider
authors.forename: Ana Cláudia
authors.initials: AC
authors.lastname: Tumelero
authors.forename: Gisele
authors.initials: G
authors.lastname: Hansel
authors.forename: Kelen Heinrich
authors.initials: KH
authors.lastname: Schmidt
authors.forename: Ana Cristina V Varrone
authors.initials: AC
authors.lastname: Giacomini
authors.forename: Felipe Vasconcelos
authors.initials: FV
authors.lastname: Torres
mesh_terms: D000367:Age Factors; D000818:Animals; D001007:Anxiety / Q000134:cerebrospinal fluid / Q000188:drug therapy* / Q000523:psychology; D003863:Depression / Q000134:cerebrospinal fluid / Q000188:drug therapy* / Q000523:psychology; D004359:Drug Therapy, Combination; D005473:Fluoxetine / Q000008:administration & dosage*; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D014364:Tryptophan / Q000008:administration & dosage* / Q000134:cerebrospinal fluid
chemical_list: D005473:Fluoxetine; D014364:Tryptophan