Mechanism of liver tyrosine aminotransferase increase in ethanol-treated mice and its effect on serum tyrosine level.
Liver tyrosine aminotransferase (TAT) activity is known to increase with ethanol treatment; however, the mechanism of this increase is unclear. Upon investigation we found that TAT activity and mRNA levels started to increase 2 h after ethanol administration and continued to increase until 6 h after ethanol administration. The increase in ethanol-induced TAT activity could not be explained by calorie loading after fasting, since ethanol loading increased TAT expression, while glucose loading decreased TAT expression. In addition, liver TAT activity was not related to serum tyrosine levels. TAT activity increased when an adenosine A2 agonist, 5'-N-ethylcarboxamide adenosine, was given. Since TAT activity is increased by cAMP, and ethanol increases cAMP production via an adenosine receptor-dependent mechanism, this increase in ethanol-induced TAT activity may occur via an adenosine receptor-dependent mechanism.
Fujimoto Sakata
Shigeko
S
Faculty of Nutrition, Kobe Gakuin University, Kobe, Japan. sakata@nutr.kobegakuin.ac.jp
Fujino
Mayumi
M
Matsuda
Koichi
K
Maeda
Mitsuko
M
Ohira
Hideo
H
Kawasaki
Koichi
K
Tamaki
Nanaya
N
D000818:Animals; D002492:Central Nervous System Depressants / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D000431:Ethanol / Q000494:pharmacology*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D008099:Liver / Q000201:enzymology*; D008297:Male; D051379:Mice; D012333:RNA, Messenger / Q000378:metabolism; D043683:Receptors, Adenosine A2 / Q000378:metabolism; D014443:Tyrosine / Q000097:blood*; D014444:Tyrosine Transaminase / Q000235:genetics / Q000378:metabolism*
D002492:Central Nervous System Depressants; D012333:RNA, Messenger; D043683:Receptors, Adenosine A2; D000431:Ethanol; D014443:Tyrosine; D014444:Tyrosine Transaminase