The Determination of Ethyl Alcohol in Blood and Tissues

Glycine receptors (GlyRs) are broadly expressed in the central nervous system. Ethanol enhances the function of brain GlyRs, and the GlyRa1 subunit is associated with some of the behavioral actions of ethanol, such as loss of righting reflex. The in vivo role of GlyRa2 and a3 subunits in alcohol responses has not been characterized despite high expression levels in the nucleus accumbens and amygdala, areas that are important for the rewarding properties of drugs of abuse. We used an extensive panel of behavioral tests to examine ethanol actions in mice lacking Glra2 (the gene encoding the glycine receptor alpha 2 subunit) or Glra3 (the gene encoding the glycine receptor alpha 3 subunit). Deletion of Glra2 or Glra3 alters specific ethanol-induced behaviors. Glra2 knockout mice demonstrate reduced ethanol intake and preference in the 24-hour two-bottle choice test and increased initial aversive responses to ethanol and lithium chloride. In contrast, Glra3 knockout mice show increased ethanol intake and preference in the 24-hour intermittent access test and increased development of conditioned taste aversion to ethanol. Mutants and wild-type mice consumed similar amounts of ethanol in the limited access drinking in the dark test. Other ethanol effects, such as anxiolysis, motor incoordination, loss of righting reflex, and acoustic startle response, were not altered in the mutants. The behavioral changes in mice lacking GlyRa2 or a3 subunits were distinct from effects previously observed in mice with knock-in mutations in the a1 subunit. We provide evidence that GlyRa2 and a3 subunits may regulate ethanol consumption and the aversive response to ethanol.

Section: Methodsmentioning

confidence: 99%

Glycine Receptors Containingα2 orα3 Subunits Regulate Specific Ethanol-Mediated Behaviors

Blednov

Benavidez

Black

et al. 2015

“…jpet.aspetjournals.org orbital sinus 30, 60, 120, 180, and 240 min after injection. Blood ethanol concentration (BEC) values, expressed as milligram of ethanol per milliliter of blood, were determined spectrophotometrically by an enzyme assay (Lundquist, 1959).…”

Section: Methodsmentioning

confidence: 99%

Behavioral Characterization of Knockin Mice with Mutations M287L and Q266I in the Glycine Receptor α1 Subunit

Blednov¹,

Benavidez²,

Homanics³

et al. 2011

We used behavioral pharmacology to characterize heterozygous knockin mice with mutations (Q266I or M287L) in the ␣1 subunit of the glycine receptor (GlyR) (J Pharmacol Exp Ther 340: 304 -316, 2012). These mutations were designed to reduce (M287L) or eliminate (Q266I) ethanol potentiation of GlyR function. We asked which behavioral effects of ethanol would be reduced more in the Q266I mutant than the M287L and found rotarod ataxia to be the behavior that fulfilled this criterion. Compared with controls, the mutant mice also differed in ethanol consumption, ethanol-stimulated startle response, signs of acute physical dependence, and duration of loss of righting response produced by ethanol, butanol, ketamine, pentobarbital, and flurazepam. Some of these behavioral changes were mimicked in wild-type mice by acute injections of low, subconvulsive doses of strychnine. Both mutants showed increased acoustic startle response and increased sensitivity to strychnine seizures. Thus, in addition to reducing ethanol action on the GlyRs, these mutations reduced glycinergic inhibition, which may also alter sensitivity to GABAergic drugs.

“…), and blood samples were taken from the retroorbital sinus 30, 60, 120, 180, and 240 min after injection. Blood ethanol concentration values, expressed as milligram of ethanol per milliliter of blood, were determined spectrophotometrically by an enzyme assay (Lundquist, 1959).…”

Section: Methodsmentioning

confidence: 99%

Loss of Ethanol Conditioned Taste Aversion and Motor Stimulation in Knockin Mice with Ethanol-Insensitive α2-Containing GABA_AReceptors

Blednov¹,

Borghese²,

McCracken³

et al. 2010

184 -191, 2008). The goal of our study was to determine the role of receptors containing this subunit in alcohol action. We designed an ␣2 subunit with serine 270 to histidine and leucine 277 to alanine mutations that was insensitive to potentiation by ethanol yet retained normal GABA sensitivity in a recombinant expression system. Knockin mice containing this mutant subunit were tested in a range of ethanol behavioral tests. These mutant mice did not develop the typical conditioned taste aversion in response to ethanol and showed complete loss of the motor stimulant effects of ethanol. Conversely, they also demonstrated changes in ethanol intake and preference in multiple tests. The knockin mice showed increased ethanolinduced hypnosis but no difference in anxiolytic effects or recovery from acute ethanol-induced motor incoordination.Overall, these studies demonstrate that the effects of ethanol at GABAergic synapses containing the ␣2 subunit are important for specific behavioral effects of ethanol that may be relevant to the genetic linkage of this subunit with human alcoholism.