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Ethanol concentration induces production of 3,4-dihydroxyphenylacetic acid and homovanillic acid in mouse brain through activation of monoamine oxidase pathway.

Ethanol concentration induces production of 3,4-dihydroxyphenylacetic acid and homovanillic acid in mouse brain through activation of monoamine oxidase pathway.

Authors :
Jamal M
Ito A
Miki T
Suzuki S
Ohta KI
Kinoshita H
Source :
Neuroscience letters [Neurosci Lett] 2022 Jun 21; Vol. 782, pp. 136689. Date of Electronic Publication: 2022 May 19.
Publication Year :
2022

Abstract

First, we aimed to investigate ex vivo the effects of ethanol (EtOH) on levels of norepinephrine (NE), dopamine (DA), serotonin (5-HT), and their metabolites in the frontal cortex, hippocampus, and striatum of Aldh2-knockout (Aldh2-KO) and wild-type (WT) mice. Animals were treated intraperitoneally with saline (control) or EtOH (1.0, 2.0, or 3.0 g/kg). Brain samples were collected 60 and 120 min after EtOH injection, and monoamines and their metabolites were measured by HPLC-ECD. We found in both WT and Aldh2-KO mice that 3.0 g/kg EtOH increased the levels of 3,4-dihydroxyphenylacetic acid (DOPAC) and homovanillic acid (HVA) and decreased the level of 3-methoxytyramine (3-MT). A 2.0 g/kg dose of EtOH also increased HVA, but there was not a consistent effect within the brain regions of Aldh2-KO and WT mice. There were inconsistent findings of genotype differences in the levels of DA, 5-HT, and their metabolites in the brain regions tested. None of the EtOH doses altered NE, DA, 5-HT, or 5-hydroxyindoleacetic acid contents in any of the brain regions studied. Second, we tested whether EtOH-induced increases in DOPAC and HVA are mediated by increased monoamine oxidase (MAO) or catechol-O-methyltransferase (COMT) activity. To test this, we used the MAO blocker clorgyline (2.0 and 4.0 mg/kg) and the COMT blocker tolcapone (15 and 30 mg/kg) alone or in combination with EtOH (3.0 g/kg). Clorgyline alone increased 3-MT and decreased DOPAC and HVA levels, whereas tolcapone alone increased DOPAC and decreased 3-MT and HVA levels. Surprisingly, the combination of EtOH with clorgyline (4.0 mg/kg) or tolcapone (30 mg/kg) further decreased 3-MT and increased DOPAC and HVA levels, an effect that reversed the inhibitor-induced decreases in HVA. These results suggest that a high concentration of EtOH can accelerate DA metabolism, as evidenced by the increase in DOPAC and HVA, and this effect is likely a consequence of increased degradation of DA by MAO.<br /> (Copyright © 2022 Elsevier B.V. All rights reserved.)

Details

Language :
English
ISSN :
1872-7972
Volume :
782
Database :
MEDLINE
Journal :
Neuroscience letters
Publication Type :
Academic Journal
Accession number :
35598694
Full Text :
https://doi.org/10.1016/j.neulet.2022.136689