The actions of ethanol on the central nervous system involve a number of biochemical sites, including the ligand-gated ion channels. Because GABA-A and glycine receptors are the major inhibitory neurotransmitter receptors in the brain and brain stem/spinal cord, respectively, enhancement of the function of these receptors by ethanol may be responsible for some of the behavioral effects of ethanol observed in vivo. There is abundant biochemical and electrophysiological evidence implicating GABA-A receptors as important sites of action of ethanol. More recently, the functioning of phylogenetically-related glycine receptors has also been shown to be affected by ethanol. The work proposed involves the study of the interactions of ethanol with glycine and GABA-A receptors on the molecular level. Chimeragenesis studies permitted the localization of ethanol action to a domain on glycine receptors encompassing transmembrane domains two (2) and three (3). Subsequent work identified two (2) amino acids that, when mutated, completely prevented ethanol enhancement of glycine and GABA-A receptor function. This proposal aims to characterize the molecular mechanisms of ethanol action on glycine and GABA-A receptors. To obtain a clearer understanding of the nature of ethanol interactions with these receptors, the amino acids implicated in ethanol action will be mutated, and the resulting receptors expressed in a mammalian cell line and tested for ethanol sensitivity using whole-cell and single-channel electrophysiological techniques.
The aims of the proposed research are: (1) To determine how mutations of amino acids in transmembrane domains of glycine and GABA-A receptor subunits render the resulting receptors to ethanol, or in some cases yield receptors displaying inhibition of receptor function by ethanol; (2) To determine if amino acids in transmembrane domains two (2) and three (3) of glycine and GABA-A receptors constitute a portion of the ethanol binding site on these receptors; and (3) To clarify the molecular mechanisms underlying the enhancing actions of ethanol on glycine and GABA-A receptor function, using the tonic opening and desensitization that occur spontaneously in some glycine and GABA-A receptor mutants.

Agency
National Institute of Health (NIH)
Institute
National Institute on Alcohol Abuse and Alcoholism (NIAAA)
Type
Research Project (R01)
Project #
5R01AA011525-09
Application #
7416790
Study Section
Special Emphasis Panel (ZRG1-IFCN-A (06))
Program Officer
Liu, Qi-Ying
Project Start
1998-05-01
Project End
2010-04-30
Budget Start
2008-05-01
Budget End
2010-04-30
Support Year
9
Fiscal Year
2008
Total Cost
$195,563
Indirect Cost
Name
University of Texas Austin
Department
Biology
Type
Schools of Arts and Sciences
DUNS #
170230239
City
Austin
State
TX
Country
United States
Zip Code
78712
Welsh, Brian T; Todorovic, Jelena; Kirson, Dean et al. (2017) Disruption of a putative intersubunit electrostatic bond enhances agonist efficacy at the human ?1 glycine receptor. Brain Res 1657:148-155
Borghese, Cecilia M; Blednov, Yuri A; Quan, Yu et al. (2012) Characterization of two mutations, M287L and Q266I, in the ?1 glycine receptor subunit that modify sensitivity to alcohols. J Pharmacol Exp Ther 340:304-16
Todorovic, Jelena; Welsh, Brian T; Bertaccini, Edward J et al. (2010) Disruption of an intersubunit electrostatic bond is a critical step in glycine receptor activation. Proc Natl Acad Sci U S A 107:7987-92
McCracken, Lindsay M; Trudell, James R; Goldstein, Beth E et al. (2010) Zinc enhances ethanol modulation of the alpha1 glycine receptor. Neuropharmacology 58:676-81
Welsh, Brian T; Kirson, Dean; Allen, Hunter M et al. (2010) Ethanol enhances taurine-activated glycine receptor function. Alcohol Clin Exp Res 34:1634-9
Welsh, Brian T; Goldstein, Beth E; Mihic, S John (2009) Single-channel analysis of ethanol enhancement of glycine receptor function. J Pharmacol Exp Ther 330:198-205
Dupre, Michelle L; Broyles, Justin M; Mihic, S John (2007) Effects of a mutation in the TM2-TM3 linker region of the glycine receptor alpha1 subunit on gating and allosteric modulation. Brain Res 1152:1-9
Roberts, Michael T; Phelan, Rachel; Erlichman, Beth S et al. (2006) Occupancy of a single anesthetic binding pocket is sufficient to enhance glycine receptor function. J Biol Chem 281:3305-11
Davies, Daryl L; Crawford, Daniel K; Trudell, James R et al. (2004) Multiple sites of ethanol action in alpha1 and alpha2 glycine receptors suggested by sensitivity to pressure antagonism. J Neurochem 89:1175-85
Davies, Daryl L; Trudell, James R; Mihic, S John et al. (2003) Ethanol potentiation of glycine receptors expressed in Xenopus oocytes antagonized by increased atmospheric pressure. Alcohol Clin Exp Res 27:743-55

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