Role of tyrosine in the acute effects of ethanol on rat brain catecholamine synthesis.
Acute ethanol administration exerts multiple effects on rat brain catecholamine synthesis, associated with corresponding changes in cerebral tyrosine concentration. Catecholamine synthesis is enhanced at 1 hr by an increased availability of circulating tyrosine to the brain after inhibition of liver tyrosine aminotransferase activity. Tyrosine hydroxylation in vivo and tyrosine hydroxylase activity measured in vitro are also enhanced at 1 hr. Catecholamine synthesis is inhibited at 2-4 hr when tyrosine availability to the brain is decreased because of an enhancement of liver tyrosine aminotransferase activity. Serum neutral amino acid concentrations are decreased at 5 hr. This is followed 1 hr later by normalization of cerebral catecholamine synthesis. By 8 hr after ethanol administration, the latter becomes enhanced because of increased cerebral uptake of tyrosine. Catecholamine synthesis is inhibited at 12 hr because of enhanced transamination of brain tyrosine. Tyrosine metabolism finally returns to normal at 16 hr after ethanol administration. These results are discussed in relation to previous work with ethanol, and to central and peripheral mechanisms of regulation of brain catecholamine synthesis.
D015102:3,4-Dihydroxyphenylacetic Acid / Q000378:metabolism; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000201:enzymology; D002395:Catecholamines / Q000378:metabolism*; D004298:Dopamine / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D000431:Ethanol / Q000494:pharmacology*; D008297:Male; D009638:Norepinephrine / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D014443:Tyrosine / Q000378:metabolism*; D014446:Tyrosine 3-Monooxygenase / Q000378:metabolism
D002395:Catecholamines; D015102:3,4-Dihydroxyphenylacetic Acid; D000431:Ethanol; D014443:Tyrosine; D014446:Tyrosine 3-Monooxygenase; D004298:Dopamine; D009638:Norepinephrine