Single-channel and whole-cell analysis of ethanol inhibition of NMDA-activated currents in cultured mouse cortical and hippocampal neurons

Wright, Jerry; Peoples, Robert W.; Weight, Forrest F.

doi:10.1016/s0006-8993(96)00780-9

Cited by 95 publications

(80 citation statements)

References 30 publications

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“…Both glycine and D-serine are considered co-agonists of NMDA receptors (Mothet et al, 2000). Some studies suggest that ethanol blocks glycine binding (Rabe and Tabakoff, 1990;Woodward and Gonzales, 1990), while others have obtained different results Wright et al, 1996). Most relevant to our studies, 1nM glycine increases NMDA activity in the SCN (Ito et al, 1991).…”

Section: Glutamate Glycine and D-serine Do Not Prevent Ethanol Inhisupporting

confidence: 43%

“…Additionally, neither excess glycine nor excess D-serine were able to overcome the inhibitory effects of ethanol. Previous studies have provided mixed results with respect to whether ethanol interferes with glycine or D-serine binding to NMDA receptors Woodward and Gonzales, 1990;Rabe and Tabakoff, 1990;Wright et al, 1996). The results here suggest that ethanol does not affect co-agonist binding to NMDA receptors in the SCN.…”

Section: Ethanol Does Not Act By Blocking Glutamate or Co-agonist Bincontrasting

confidence: 40%

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Acute ethanol modulates glutamatergic and serotonergic phase shifts of the mouse circadian clock in vitro

2008

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Alcohol abuse is associated with sleep problems, which are often linked to circadian rhythm disturbances. However, there is no information on the direct effects of ethanol on the mammalian circadian clock. Acute ethanol inhibits glutamate signaling, which is the primary mechanism through which light resets the mammalian clock in the suprachiasmatic nucleus (SCN). Glutamate and light also inhibit circadian clock resetting induced by non-photic signals, including serotonin. Thus, we investigated the effects of acute ethanol on both glutamatergic and serotoninergic resetting of the SCN clock in vitro. We show that ethanol dose-dependently inhibits glutamate-induced phase shifts and enhances serotonergic phase shifts. The inhibition of glutamate-induced phase shifts is not affected by excess glutamate, glycine or D-serine, but is prevented by excess brain-derived neurotrophic factor (BDNF). BDNF is known to augment glutamate signaling in the SCN and to be necessary for glutamate/light-induced phase shifts. Thus, ethanol may inhibit glutamate-induced clock resetting at least in part by blocking BDNF enhancement of glutamate signaling. Ethanol enhancement of serotonergic phase shifts is mimicked by treatments that suppress glutamate signaling in the SCN, including antagonists of glutamate receptors, BDNF signaling and nitric oxide synthase. The combined effect of ethanol with these treatments is not additive, suggesting they act through a common pathway. Our data indicate further that the interaction between serotonin and glutamate in the SCN may occur downstream from nitric oxide synthase activation. Thus, acute ethanol disrupts normal circadian clock phase regulation, which could contribute to the physiological and psychological problems associated with alcohol abuse. Keywords suprachiasmatic nucleus; circadian rhythms; ethanol; glutamate; serotonin; brain-derived neurotrophic factorThe development of alcoholism and the likelihood of relapse drinking are associated with poor sleep quality and the deleterious effects of ethanol on sleep (Landolt and Gillin, 2001;Brower et al., 2001). Alcohol consumption reduces sleep quality (Kubota et al., 2002;Ehler and Slawecki, 2000;Landolt et al., 1996), which is closely linked to the circadian system. For example, the inability to fall asleep at the desired time can result from improper synchronization *Corresponding author: Dept. Biochemistry and Cellular and Molecular Biology, University of Tennessee, Knoxville, TN 37996, phone: (865) 974-2722, FAX: (865)-974-6306, rprosser@utk.edu. Publisher's Disclaimer: This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final citable form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal per...

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Section: Glutamate Glycine and D-serine Do Not Prevent Ethanol Inhisupporting

confidence: 43%

Section: Ethanol Does Not Act By Blocking Glutamate or Co-agonist Bincontrasting

confidence: 40%

Acute ethanol modulates glutamatergic and serotonergic phase shifts of the mouse circadian clock in vitro

2008

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“…It is also important to keep in mind that there is strong evidence that ethanol may have direct effects on the NMDAR (45). Moreover, it has been shown that ethanol effects on the NMDAR can be very rapid and may alter NMDAR channel kinetics (46). Thus, if STEP is involved in such effects, it may not be via dephosphorylation of sites involved in trafficking but rather in gating of the NMDAR.…”

Section: Discussionmentioning

confidence: 99%

Alcohol inhibition of the NMDA receptor function, long-term potentiation, and fear learning requires striatal-enriched protein tyrosine phosphatase

Hicklin¹,

Radcliffe

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

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Alcohol's deleterious effects on memory are well known. Acute alcohol-induced memory loss is thought to occur via inhibition of NMDA receptor (NMDAR)-dependent long-term potentiation in the hippocampus. We reported previously that ethanol inhibition of NMDAR function and long-term potentiation is correlated with a reduction in the phosphorylation of Tyr 1472 on the NR2B subunit and ethanol's inhibition of the NMDAR field excitatory postsynaptic potential was attenuated by a broad spectrum tyrosine phosphatase inhibitor. These data suggested that ethanol's inhibitory effect may involve protein tyrosine phosphatases. Here we demonstrate that the loss of striatal-enriched protein tyrosine phosphatase (STEP) renders NMDAR function, phosphorylation, and long-term potentiation, as well as fear conditioning, less sensitive to ethanol inhibition. Moreover, the ethanol inhibition was "rescued" when the active STEP protein was reintroduced into the cells. Taken together, our data suggest that STEP contributes to ethanol inhibition of NMDAR function via dephosphorylation of tyrosine sites on NR2B receptors and lend support to the hypothesis that STEP may be required for ethanol's amnesic effects.whole-cell currents | null mutant mice A lcohol-induced memory deficits have been well documented in humans, as well as animal studies (1). Long-term potentiation (LTP) is widely accepted as a cellular mechanism underlying learning and memory in the hippocampus, as well as other brain regions (2), and is dependent upon NMDA receptor (NMDAR) activation (3). Acute ethanol application in adult rodents inhibits NMDAR channel activity (4, 5). Ethanol's inhibitory effect on NMDARs is widely thought to underlie both the blockade of LTP and the acute amnesic effects of ethanol. Moreover, recent work suggests that ethanol's effect on the NMDAR may play a role in the addictive nature of ethanol (6, 7).NMDARs in the hippocampus consist of mainly NR1/NR2A, NR1/NR2B, and NR1/NR2A/NR2B receptor-subunit complexes (8). Although NR1 subunits are required to form an active ion channel, incorporation of the various NR2 subunits regulate NMDAR channel activity by altering the channel kinetics and mediating the differential effects of pharmacological agents, including alcohol (9-11). It has previously been shown that activation of members of the Src-family of kinases (SFKs) enhances NMDAR currents (12). Previous studies have demonstrated a correlation between ethanol inhibition of NMDAR function and dephosphorylation of tyrosine residues on the NR2A and NR2B subunits (13). In particular, ethanol was found to reduce the phosphorylation of a site on the NR2B subunit Tyr 1472 that has been shown to regulate endocytosis and function of NMDARs (14,15). Inhibition of protein tyrosine phosphatase activity using a nonspecific inhibitor, bpV(phen), significantly reduced ethanol inhibition of NMDAR field excitatory postsynaptic potentials (fEPSPs), suggesting that ethanol may inhibit NMDARs via activation of a tyrosine phosphatase (13). FerraniKile et al. indepe...

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“…Ethanol behaves as a noncompetitive and voltage-independent antagonist of the receptor, and attempts to correlate its inhibitory actions with any of the known modulatory sites on the receptor have been largely negative (14 -16). In single-channel studies, the inhibitory effects of ethanol were best accounted for by decreases in the mean open time and frequency of channel opening, effects consistent with an allosteric reduction in agonist-induced channel gating (17).…”

Section: N-methyl-d-aspartate (Nmda)mentioning

confidence: 91%

Ethanol Inhibition ofN-Methyl-d-aspartate Receptors Is Reduced by Site-directed Mutagenesis of a Transmembrane Domain Phenylalanine Residue

Ronald

Mirshahi

Woodward

2001

Journal of Biological Chemistry

113

105

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N-Methyl-D-aspartate (NMDA) receptors (NRs) are ionotropic receptors activated by glutamate and the coagonist glycine. Ethanol inhibits NMDA receptor function, although its site of action is undefined. We hypothesized that ethanol acts at specific amino acids contained within the transmembrane (TM) domains of the receptor. In this study, NR1 and NR2A subunits were altered by mutagenesis and tested for sensitivity to ethanol. Three NR1 mutants (W636A, F817A, and L819A) and one NR2A mutant (F637A) failed to generate functional receptors. Pre-TM1 (I546A, L551A, F554A, and F558A), TM1 (W563A), and TM2 (W611A) NR1 mutations did not affect ethanol sensitivity of heteromeric receptors. In contrast, altering a TM3 phenylalanine to alanine (F639A) reduced the ethanol inhibition of NMDA receptors expressed in oocytes and human embryonic kidney 293 cells. Mutation of the nearby methionine (M641) to alanine did not affect ethanol sensitivity, whereas changing Phe 639 to tryptophan slightly enhanced ethanol inhibition. NR1(F639A) did not alter the agonist potency of glutamate but did produce a leftward shift in the glycine concentration response for receptors containing NR2A and NR2B subunits. NR1(F639A) also reduced the potency of the competitive glycine antagonist 5,7-dichlorokynurenic acid and increased the efficacy of the glycine partial agonist 3-amino-1-hydroxy-2-pyrrolidinone ((؉)-HA-966). These results suggest that ethanol may interact with amino acids contained in the TM3 domain of NMDA subunits that are involved in transducing agonist binding to channel opening. N-Methyl-D-aspartate (NMDA)1 receptors are calcium-permeable ion channels expressed by neurons and require both glutamate and glycine for activation. Combinations of NMDA receptor 1 (NR1) and NR2 subunits yield receptors with different biophysical and pharmacological properties such as differences in desensitization and sensitivity to agonists and antagonists. NMDA receptors play an important role in neuronal development and are required for some forms of synaptic plasticity such as associative long-term potentiation that may underlie some forms of learning and memory (1). NMDA receptors are also involved in the excitotoxic effects of glutamate that accompany traumatic brain injury and stroke-induced ischemia.Ethanol inhibits native NMDA receptor function in vitro and in vivo (2-7). Chronic exposure of neurons to ethanol results in up-regulation of NMDA receptor function and enhanced glutamate-mediated excitotoxicity (8 -10). NMDA antagonists block the seizures associated with ethanol withdrawal (11, 12), and human alcoholics report ethanol-like subjective effects after administration of ketamine, a nondissociative anesthetic that inhibits NMDA channel function (13). Despite the wealth of knowledge indicating that the NMDA receptor is an important target for ethanol in the brain, there is no consensus as to how ethanol inhibits receptor function. Ethanol behaves as a noncompetitive and voltage-independent antagonist of the receptor, and attempts to correlat...

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Single-channel and whole-cell analysis of ethanol inhibition of NMDA-activated currents in cultured mouse cortical and hippocampal neurons

Cited by 95 publications

References 30 publications

Acute ethanol modulates glutamatergic and serotonergic phase shifts of the mouse circadian clock in vitro

Acute ethanol modulates glutamatergic and serotonergic phase shifts of the mouse circadian clock in vitro

Alcohol inhibition of the NMDA receptor function, long-term potentiation, and fear learning requires striatal-enriched protein tyrosine phosphatase

Ethanol Inhibition ofN-Methyl-d-aspartate Receptors Is Reduced by Site-directed Mutagenesis of a Transmembrane Domain Phenylalanine Residue

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