Tryptophan 2,3-dioxygenase is a key modulator of physiological neurogenesis and anxiety-related behavior in mice

Although nutrients, including amino acids and their metabolites such as serotonin (5-HT), are strong modulators of anxiety-related behavior, the metabolic pathway(s) responsible for this physiological modulation is not fully understood. Regarding tryptophan (Trp), the initial rate-limiting enzymes f...

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Bibliographic Details
Published in:Molecular brain 2009-03, Vol.2 (1), p.8-8, Article 8
Main Authors: Kanai, Masaaki, Funakoshi, Hiroshi, Takahashi, Hisaaki, Hayakawa, Tomoko, Mizuno, Shinya, Matsumoto, Kunio, Nakamura, Toshikazu
Format: Article
Language:English
Subjects:
Aging - metabolism
Amino acid metabolism
Animals
Anxiety - enzymology
Anxiety - physiopathology
Behavior, Animal
Cell differentiation
Cell Proliferation
Cerebral Ventricles - metabolism
Cerebral Ventricles - pathology
Dentate Gyrus - metabolism
Dentate Gyrus - pathology
Gene Deletion
Gene Targeting
Genetic Loci - genetics
Indoleamine-Pyrrole 2,3,-Dioxygenase - deficiency
Indoleamine-Pyrrole 2,3,-Dioxygenase - metabolism
Mice
Neural Stem Cells - cytology
Neural Stem Cells - metabolism
Neurogenesis - physiology
Neurons
Olfactory Bulb - metabolism
Olfactory Bulb - pathology
Physiological aspects
Serotonin - metabolism
Tryptophan
Tryptophan - blood
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Summary:Although nutrients, including amino acids and their metabolites such as serotonin (5-HT), are strong modulators of anxiety-related behavior, the metabolic pathway(s) responsible for this physiological modulation is not fully understood. Regarding tryptophan (Trp), the initial rate-limiting enzymes for the kynurenine pathway of tryptophan metabolism are tryptophan 2,3-dioxygenase (TDO) and indoleamine 2,3-dioxygenase (IDO). Here, we generated mice deficient for tdo (Tdo(-/-)). Compared with wild-type littermates, Tdo(-/-) mice showed increased plasma levels of Trp and its metabolites 5-hydroxyindoleacetic acid (5-HIAA) and kynurenine, as well as increased levels of Trp, 5-HT and 5-HIAA in the hippocampus and midbrain. These mice also showed anxiolytic modulation in the elevated plus maze and open field tests, and increased adult neurogenesis, as evidenced by double staining of BrdU and neural progenitor/neuronal markers. These findings demonstrate a direct molecular link between Trp metabolism and neurogenesis and anxiety-related behavior under physiological conditions.
ISSN:1756-6606
1756-6606
DOI:10.1186/1756-6606-2-8