RT Journal Article
SR Electronic
T1 Mutation of a Zinc-Binding Residue in the Glycine Receptor α1 Subunit Changes Ethanol Sensitivity In Vitro and Alcohol Consumption In Vivo
JF Journal of Pharmacology and Experimental Therapeutics
JO J Pharmacol Exp Ther
FD American Society for Pharmacology and Experimental Therapeutics
SP 489
OP 500
DO 10.1124/jpet.112.197707
VO 344
IS 2
A1 McCracken, Lindsay M.
A1 Blednov, Yuri A.
A1 Trudell, James R.
A1 Benavidez, Jillian M.
A1 Betz, Heinrich
A1 Harris, R. Adron
YR 2013
UL http://jpet.aspetjournals.org/content/344/2/489.abstract
AB Ethanol is a widely used drug, yet an understanding of its sites and mechanisms of action remains incomplete. Among the protein targets of ethanol are glycine receptors (GlyRs), which are potentiated by millimolar concentrations of ethanol. In addition, zinc ions also modulate GlyR function, and recent evidence suggests that physiologic concentrations of zinc enhance ethanol potentiation of GlyRs. Here, we first built a homology model of a zinc-bound GlyR using the D80 position as a coordination site for a zinc ion. Next, we investigated in vitro the effects of zinc on ethanol action at recombinant wild-type (WT) and mutant α1 GlyRs containing the D80A substitution, which eliminates zinc potentiation. At D80A GlyRs, the effects of 50 and 200 mM ethanol were reduced as compared with WT receptors. Also, in contrast to what was seen with WT GlyRs, neither adding nor chelating zinc changed the magnitude of ethanol enhancement of mutant D80A receptors. Next, we evaluated the in vivo effects of the D80A substitution by using heterozygous Glra1(D80A) knock-in (KI) mice. The KI mice showed decreased ethanol consumption and preference, and they displayed increased startle responses compared with their WT littermates. Other behavioral tests, including ethanol-induced motor incoordination and strychnine-induced convulsions, revealed no differences between the KI and WT mice. Together, our findings indicate that zinc is critical in determining the effects of ethanol at GlyRs and suggest that zinc binding at the D80 position may be important for mediating some of the behavioral effects of ethanol action at GlyRs.