Brain levels and turnover rates of presumptive neurotransmitters as influenced by administration and withdrawal of ethanol in mice.

Abstract

Abstract—Effects of acute or chronic administration of ethanol and its withdrawl on the steady‐state levels and turnover rates of certain neurotransmitters have been investigated in mice. The influence of long‐term administration of ethanol on the activities of enzymes involved in the metabolism of these transmitters has also been studied. Acute administration of ethanol or acetaldehyde or chronic administration of ethanol resulted in a decrease in the cerebral contents of acetylcholine, acetylCoA and CoA. Brain levels of 5‐hydroxytryptamine, norepinephrine and choline remained unchanged after acute administration of ethanol. However, chronic administration of ethanol resulted in a decrease in the norepinephrine content without significantly affecting 5‐hydroxytryptamine or choline contents. Cerebral levels of γ‐aminobutyric acid increased with both acute or chronic administration of ethanol. The total incorporation of [3H]choline into acetylcholine in brain was depressed upon acute administration of ethanol. After withdrawal of ethanol for one day cerebral levels of norepinephrine returned to normal; however, γ‐aminobutyric acid and acetylcholine returned to normal levels at 2 and 4 days after ethanol withdrawal, respectively. Pretreatment of mice with pyrazole, an inhibitor of alcohol dehydrogenase, prevented the ethanol‐induced decrease in cerebral acetylcholine levels. The activities of cerebral choline acetyltransferase and glutamic decarboxylase were decreased after 2 weeks of chronic ethanol administration. However, the activities of acetyl cholinesterase and GABA‐transaminase remained unaffected after 2 weeks of ethanol treatment