Jonathan H Lindsay1, Rebecca A Prosser1. 1. Department of Biochemistry and Cellular and Molecular Biology (JHL, RAP), University of Tennessee Knoxville, NeuroNET Research Center, Knoxville, Tennessee.
Abstract
BACKGROUND: Alcohol tolerance and withdrawal-induced effects are criteria for alcohol use disorders listed by the DSM-V. Although tolerance and withdrawal have been studied over many decades, there is still uncertainty regarding mechanistic distinctions that characterize these different forms of ethanol (EtOH)-induced plasticity. Previously, we demonstrated that the suprachiasmatic nucleus (SCN) circadian clock develops both acute and rapid tolerance to EtOH inhibition of glutamate-induced circadian phase shifts. Here, we demonstrate that chronic EtOH tolerance and withdrawal-induced glutamate hypersensitivity occur in vitro and that rapid tolerance, chronic tolerance, and glutamate hypersensitivity have distinct cellular changes. METHODS: We use single-unit extracellular electrophysiological recordings to determine whether chronic tolerance to EtOH inhibition of glutamatergic phase shifts and withdrawal-induced glutamate hypersensitivity develop in the SCN. We use Western blotting to compare phosphorylation state and total expression of N-methyl-D-aspartate (NMDA) receptor subunits and associated proteins in the SCN after mice were exposed to varying EtOH consumption paradigms. RESULTS: Chronic tolerance developed after a minimum of 8 days of 4 h/d EtOH access, as indicated by a decreased sensitivity to EtOH inhibition of glutamate-induced phase shifts. We also observed an increased sensitivity to glutamate-induced phase shifts in SCN tissue following withdrawal. We demonstrated an increase in the ratio of NR2B:NR2A NMDA receptor subunit expression after 21 days, but not after 10 days of EtOH drinking. This increase persisted during EtOH withdrawal, along with an increase in NR2B Y1472 phosphorylation, mature brain-derived neurotrophic factor, and phosphorylated TrkB. CONCLUSIONS: These results demonstrate that multiple tolerance forms and withdrawal-induced glutamate hypersensitivity occur in the SCN and that these different forms of EtOH-induced plasticity are accompanied by distinct changes in cellular physiology. Importantly, this study further demonstrates the power of using the SCN as a model system to investigate EtOH-induced plasticity.
BACKGROUND:Alcohol tolerance and withdrawal-induced effects are criteria for alcohol use disorders listed by the DSM-V. Although tolerance and withdrawal have been studied over many decades, there is still uncertainty regarding mechanistic distinctions that characterize these different forms of ethanol (EtOH)-induced plasticity. Previously, we demonstrated that the suprachiasmatic nucleus (SCN) circadian clock develops both acute and rapid tolerance to EtOH inhibition of glutamate-induced circadian phase shifts. Here, we demonstrate that chronic EtOH tolerance and withdrawal-induced glutamatehypersensitivity occur in vitro and that rapid tolerance, chronic tolerance, and glutamatehypersensitivity have distinct cellular changes. METHODS: We use single-unit extracellular electrophysiological recordings to determine whether chronic tolerance to EtOH inhibition of glutamatergic phase shifts and withdrawal-induced glutamatehypersensitivity develop in the SCN. We use Western blotting to compare phosphorylation state and total expression of N-methyl-D-aspartate (NMDA) receptor subunits and associated proteins in the SCN after mice were exposed to varying EtOH consumption paradigms. RESULTS: Chronic tolerance developed after a minimum of 8 days of 4 h/d EtOH access, as indicated by a decreased sensitivity to EtOH inhibition of glutamate-induced phase shifts. We also observed an increased sensitivity to glutamate-induced phase shifts in SCN tissue following withdrawal. We demonstrated an increase in the ratio of NR2B:NR2ANMDA receptor subunit expression after 21 days, but not after 10 days of EtOH drinking. This increase persisted during EtOH withdrawal, along with an increase in NR2BY1472 phosphorylation, mature brain-derived neurotrophic factor, and phosphorylated TrkB. CONCLUSIONS: These results demonstrate that multiple tolerance forms and withdrawal-induced glutamatehypersensitivity occur in the SCN and that these different forms of EtOH-induced plasticity are accompanied by distinct changes in cellular physiology. Importantly, this study further demonstrates the power of using the SCN as a model system to investigate EtOH-induced plasticity.
Authors: R L Bell; R B Stewart; J E Woods ; L Lumeng; T K Li; J M Murphy ; W J McBride Journal: Alcohol Clin Exp Res Date: 2001-05 Impact factor: 3.455
Authors: Marisa Roberto; Steven N Treistman; Andrzej Z Pietrzykowski; Jeff Weiner; Rafael Galindo; Manuel Mameli; Fernando Valenzuela; Ping Jun Zhu; David Lovinger; Tao A Zhang; Adam H Hendricson; Richard Morrisett; George Robert Siggins Journal: Alcohol Clin Exp Res Date: 2006-02 Impact factor: 3.455
Authors: L M Wang; A Schroeder; D Loh; D Smith; K Lin; J H Han; S Michel; D L Hummer; J C Ehlen; H E Albers; C S Colwell Journal: Eur J Neurosci Date: 2008-04 Impact factor: 3.386