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Ethanol Increases GABA A Responses in Cells Stably Transfected with Receptor Subunits
Author(s) -
Harris R. Adron,
Proctor William R.,
McQuilkin Susan J.,
Klein Ronald L.,
Mascia Maria Paola,
Whatley Valerie,
Whiting Paul J.,
Dunwiddie Thomas V.
Publication year - 1995
Publication title -
alcoholism: clinical and experimental research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.267
H-Index - 153
eISSN - 1530-0277
pISSN - 0145-6008
DOI - 10.1111/j.1530-0277.1995.tb01496.x
Subject(s) - gabaa receptor , receptor , ethanol , biophysics , protein subunit , gamma subunit , chemistry , transfection , patch clamp , gabaa rho receptor , biochemistry , biology , microbiology and biotechnology , gene
Ethanol enhancement of GABA A receptor function has been found in some, but not all, studies. These results suggest the existence of ethanol‐sensitive and ‐resistant receptors that may differ in subunit composition, although methodological differences (e.g., 38 Cl ‐ flux versus membrane currents) could also contribute to the different results. To examine these possibilities, we used mouse L(tk ‐ ) cells stably transfected with α 1 +β or α+β 1 +γ 2L GABA A receptor subunit DNAs and compared 38 Cl flux with whole‐cell, patch‐clamp measurements of GABA A receptor function. Both techniques detected a similar modulation of the GABA receptor by ethanol, flunitrazepam, and pentobarbital. The potentiating action of ethanol required the ‐γ‐subunit and was maximal at a concentration of 10 m m . Similar ethanol potentiation was obtained with brief (20 msec) or long (2 sec) applications of GABA. Analysis of data obtained from individual cells expressing α 1 β 1‐ γ 2L subunits showed considerable variability in sensitivity to ethanol, particularly with concentrations of 30 and 100 m m . Ethanol potentiated GABA action if the cells were grown on coverslips coated with polylysine, but had no effect on GABA A receptors of cells grown on uncoated coverslips. Thus, ethanol action was influenced by the growth matrix. Taken together, these data indicate that a y‐subunit is necessary, but not sufficient, for ethanol sensitivity in this cell system. We suggest that posttranslational processing, particularly receptor phosphorylation, may also be important and that stably transfected cells will be useful in elucidating these events.