title: Comparison of centrally injected tryptophan-related substances inducing sedation in acute isolation stress-induced neonatal chicks.
abstract: In the present study, we first focused on the function of l-tryptophan (TRP) metabolites which are synthesized in different metabolic pathways, namely, the kynurenine (KYN) pathway and serotonin (5-HT) pathway during an acute isolation stress. When l-TRP metabolites were intracerebroventricularly injected on an equimolar basis (100 nmol), 5-HT induced a sedative effect in neonatal chicks. Additionally, plasma corticosterone, dopamine, 5-HT, and its metabolite 5-hydroxyindoleacetic acid concentrations were increased in the diencephalon of the 5-HT treated group compared with other groups. Second, the two doses (400 or 800 nmol) of l- and d-TRP were compared under a corticotrophin-releasing hormone-augmented social isolation stress. When comparing the efficacy between l- and d-TRP against stress behavior, both amino acids had a similar effect and quickly suppressed distress vocalizations. Finally, d-amino acid levels in the diencephalon and telencephalon were measured but d-TRP was not found. These results indicate that l- and d-TRP induce the same effect in attenuating stress but the mode of action of TRP derivatives, namely 5-HT differs during an acute isolation stress in neonatal chick. The absence of d-TRP in the diencephalon further suggests that instead of being an endogenous factor it may play role as a pharmacological factor.
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Junki
authors.initials: J
authors.lastname: Yoshida
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Edi
authors.initials: E
authors.lastname: Erwan
authors.affiliation: Division for Arts and Science, Faculty of Arts and Science, Kyushu University, Fukuoka 819-0395, Japan.
authors.forename: Vishwajit Sur
authors.initials: VS
authors.lastname: Chowdhury
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Yumi
authors.initials: Y
authors.lastname: Ogino
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan.
authors.forename: Asako
authors.initials: A
authors.lastname: Shigemura
authors.affiliation: Department of Animal and Poultry Sciences, Virginia Tech, Blacksburg, VA 24061-0306, USA.
authors.forename: D Michael
authors.initials: DM
authors.lastname: Denbow
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka 812-8581, Japan. Electronic address: furuse@brs.kyushu-u.ac.jp.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Furuse
mesh_terms: D000818:Animals; D002645:Chickens; D006993:Hypnotics and Sedatives / Q000008:administration & dosage*; D007276:Injections, Intraventricular; D012934:Social Isolation; D013315:Stress, Psychological; D014364:Tryptophan / Q000008:administration & dosage* / Q000031:analogs & derivatives
chemical_list: D006993:Hypnotics and Sedatives; D014364:Tryptophan
keywords: Acute stress; Kynurenine; Neonatal chick; Serotonin; l- and d-tryptophan