title: Metabolism of amino acids differs in the brains of Djungarian hamster (P. sungorus) and Roborovskii hamster (P. roborovskii).
abstract: Djungarian hamster (P. sungorus) and Roborovskii hamster (P. roborovskii) belong to the same genus of phodopus. Roborovskii hamster shows high locomotor activity and low level of dopamine (DA) in the brain. Administration of L-tyrosine, a precursor of DA, decreases locomotor activity in Roborovskii hamsters. However, the amino acid metabolism in relation to the hyperactivity is not yet well known. In the present study, L- and D-amino acid concentrations in the brain, liver, and plasma in Djungarian and Roborovskii hamsters were investigated during day and night times to explain the possible difference in hyperactivity between them. Most of the examined amino acids were higher in the night time when hamsters are active compared to those in day time. L- and D-tyrosine concentrations were higher in the liver of Roborovskii hamsters than in Djungarian hamsters. Furthermore, brain concentration of D-tyrosine was higher in the Roborovskii than in Djungarian hamsters, but no significant difference was observed for L-tyrosine concentrations between the two species. These results suggest that the conversion of L-tyrosine to D-tyrosine in the brain of Roborovskii hamster may be higher than in Djungarian hamster, which may cause low DA concentration and hyperactivity in Roborovskii hamster. On the other hand, L- and D-serine, which are known as sedative factors, were lower in Roborovskii hamsters than Djungarian hamster. These results suggest that species-specific regulation in amino acid metabolism may contribute to hyperactivity in Roborovskii hamsters.
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka, 812-8581 Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Ikeda
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka, 812-8581 Japan.
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kawase
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka, 812-8581 Japan.
authors.forename: Mao
authors.initials: M
authors.lastname: Nagasawa
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: Shinobu
authors.initials: S
authors.lastname: Yasuo
authors.affiliation: Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, Fukuoka, 812-8581 Japan.
authors.forename: Mitsuhiro
authors.initials: M
authors.lastname: Furuse
keywords: Brain; D-Tyrosine; Djungarian hamsters; L-Tyrosine; Roborovskii hamsters