Inverse correlation between the nitrogen balance and induction of rat liver serine dehydratase (SDH) by dietary protein.
Rats of different ages (3 to 15-wk-old) were fed on a 25% casein diet for one week, and the nitrogen balance and liver serine dehydratase (SDH, EC 4.2.1.13) activity were then determined. The value for nitrogen balance decreased with the age of the rats, while the liver SDH activity increased. A statistical analysis showed clear inverse correlation between the two factors (R(2) = 0.7372, p < 0.01). This result suggests that SDH was induced by response to the amount of surplus amino acids from dietary protein taken beyond the body's requirement. The increase in SDH activity was accompanied by an increase in the level of SDH mRNA. Since the half-life of this mRNA did not change significantly, the induction was mainly controlled at the level of transcription. In addition, the induction seems not to be related to gluconeogenesis, since the mRNA levels of tyrosine aminotransferase (TAT) and phosphoenolpyruvate carboxykinase (PEPCK), other gluconeogenic enzymes, were not changed under these experimental conditions.
Kanamoto
Ryuhei
R
Department of Biological Resource Chemistry, Kyoto Prefectural University, Japan. kanamoto@kpu.ac.jp
Fujita
Kousuke
K
Kumasaki
Megumi
M
Imai
Saeko
S
Kotaru
Makoto
M
Saeki
Tohru
T
Iwami
Kimikazu
K
D000375:Aging / Q000502:physiology; D000818:Animals; D001835:Body Weight / Q000187:drug effects; D002364:Caseins / Q000008:administration & dosage / Q000494:pharmacology; D004044:Dietary Proteins / Q000008:administration & dosage / Q000494:pharmacology*; D004790:Enzyme Induction / Q000187:drug effects; D005508:Food Deprivation; D006207:Half-Life; D012695:L-Serine Dehydratase / Q000235:genetics* / Q000378:metabolism*; D008099:Liver / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D008297:Male; D009584:Nitrogen / Q000378:metabolism*; D019764:Phosphoenolpyruvate Carboxykinase (ATP) / Q000235:genetics; D020871:RNA Stability; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D014444:Tyrosine Transaminase / Q000235:genetics
D002364:Caseins; D004044:Dietary Proteins; D012333:RNA, Messenger; D014444:Tyrosine Transaminase; D019764:Phosphoenolpyruvate Carboxykinase (ATP); D012695:L-Serine Dehydratase; D009584:Nitrogen