Distribution of D-3-aminoisobutyrate-pyruvate aminotransferase in the rat brain.
BACKGROUND
D-3-aminoisobutyrate, an intermediary product of thymine, is converted to 2-methyl-3-oxopropanoate using pyruvate as an amino acceptor by D-3-aminoisobutyrate-pyruvate aminotransferase (D-AIB AT; EC 2.6.1.40). A large amount of D-AIB AT is distributed in the kidney and liver; however, small amounts are found in the brain. Recently, D-AIB AT was reported to metabolize asymmetric dimethylarginine (ADMA) in vivo and was suggested to be an important enzyme for nitric oxide metabolism because ADMA is a competitive inhibitor for nitric oxide synthase. In this study, we examined the distribution of D-AIB AT in the rat brain further to understand its role. We measured D-AIB AT mRNA and protein expression using quantitative RT-PCR and Western blotting, and monitored its distribution using immunohistochemical staining.


RESULTS
D-AIB AT was distributed throughout the brain, with high expression in the cortex and hippocampus. Immunohistochemical staining revealed that D-AIB AT was highly expressed in the retrosplenial cortex and in hippocampal neurons.


CONCLUSIONS
Our results suggest that D-AIB AT is distributed in the examined- just the regions and may play an important role there.
Department of Neuropsychiatry, Ehime University Graduate School of Medicine, Shitsukawa, Toon, Ehime 791-0295, Japan. masao-a@m.ehime-u.ac.jp.
Masao
M
Abe
Shinichiro
S
Ochi
Yoko
Y
Mori
Kiyohiro
K
Yamazaki
Takashi
T
Ishimaru
Yuta
Y
Yoshino
Ryuji
R
Fukuhara
Satoshi
S
Tanimukai
Seiji
S
Matsuda
Shu-Ichi
S
Ueno
D000818:Animals; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000201:enzymology*; D006624:Hippocampus / Q000201:enzymology*; D008297:Male; D009474:Neurons / Q000201:enzymology*; D009928:Organ Specificity; D051381:Rats; D017208:Rats, Wistar; D014018:Tissue Distribution; D000637:Transaminases / Q000378:metabolism*
D000637:Transaminases; C019685:D-3-aminoisobutyrate-pyruvate aminotransferase