title: Ethanol-Induced ADH Activity in Zebrafish: Differential Concentration-Dependent Effects on High- Versus Low-Affinity ADH Enzymes.
abstract: Zebrafish express enzymes that metabolize ethanol in a manner comparable to that of mammals, including humans. We previously demonstrated that acute ethanol exposure increases alcohol dehydrogenase (ADH) activity in an inverted U-shaped dose-dependent manner. It was hypothesized that the biphasic dose-response was due to the increased activity of a high-affinity ADH isoform following exposure to low concentrations of ethanol and increased activity of a low-affinity ADH isoform following exposure to higher concentrations of ethanol. To test this hypothesis, we exposed zebrafish to different concentrations of ethanol (0%, 0.25%, 0.5%, and 1.0% v/v) for 30 min and measured the total ADH activity in the zebrafish liver. However, we also repeated this enzyme activity assay using a low concentration of the substrate (ethanol) to determine the activity of high-affinity ADH isoforms. We found that total ADH activity in response to ethanol induces an inverted U-shaped dose-response similar to our previous study. Using a lower substrate level in our enzyme assay targeting high-affinity isozymes, we found a similar dose-response. However, the difference in activity between the high and low substrate assays (high substrate activity - low substrate activity), which provide an index of activity for low-affinity ADH isoforms, revealed no significant effect of ethanol exposure. Our results suggest that the inverted U-shaped dose-response for total ADH activity in response to ethanol is driven primarily by high-affinity isoforms of ADH.
authors.affiliation: 1 Department of Cell and Systems Biology, University of Toronto , Toronto, Ontario, Canada .
authors.forename: Steven
authors.initials: S
authors.lastname: Tran
authors.affiliation: 2 Department of Psychology, University of Toronto Mississauga , Mississauga, Ontario, Canada .
authors.forename: Magda
authors.initials: M
authors.lastname: Nowicki
authors.affiliation: 2 Department of Psychology, University of Toronto Mississauga , Mississauga, Ontario, Canada .
authors.forename: Amanda
authors.initials: A
authors.lastname: Facciol
authors.affiliation: 2 Department of Psychology, University of Toronto Mississauga , Mississauga, Ontario, Canada .
authors.forename: Diptendu
authors.initials: D
authors.lastname: Chatterjee
authors.affiliation: 1 Department of Cell and Systems Biology, University of Toronto , Toronto, Ontario, Canada .|2 Department of Psychology, University of Toronto Mississauga , Mississauga, Ontario, Canada .
authors.forename: Robert
authors.initials: R
authors.lastname: Gerlai
mesh_terms: D000426:Alcohol Dehydrogenase / Q000032:analysis / Q000378:metabolism*; D000818:Animals; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D000431:Ethanol / Q000494:pharmacology*; D005260:Female; D007527:Isoenzymes / Q000032:analysis / Q000378:metabolism; D008099:Liver / Q000187:drug effects* / Q000201:enzymology*; D008297:Male; D015027:Zebrafish / Q000378:metabolism*
chemical_list: D007527:Isoenzymes; D000431:Ethanol; D000426:Alcohol Dehydrogenase