Acute ethanol affects phosphorylation state of the NMDA receptor complex: implication of tyrosine phosphatases and protein kinase A.
Phosphorylation has been shown to regulate N-methyl-D-aspartic acid receptor (NMDAR) function. The inhibitory effect of ethanol on NMDAR function could be due, at least in part, to a change in NMDAR phosphorylation states. In order to investigate the effect of ethanol on phosphorylation of NR1 and NR2 subunits, NMDAR complexes were immunoprecipitated from cortical slices pre-exposed to ethanol. Acute ethanol, 100 and 200 mM, significantly decreased the tyrosine phosphorylation of NR2 subunits (Tyr-NR2). Treatment with a tyrosine phosphatase inhibitor reduced the inhibition of Tyr-NR2 phosphorylation caused by 100 mM ethanol. This suggests an involvement of tyrosine phosphatases in ethanol-induced inhibition of Tyr-NR2 phosphorylation. Slices pre-exposed to 100 and 200 mM ethanol exhibited a significant increase in the phosphorylation of NR1 by PKA at serine 897 (Ser897-NR1), which was blocked by a PKA inhibitor. Moreover, at 200 mM, ethanol produced a significant increase in PKA activity. Together, these results indicate that ethanol may increase Ser897-NR1 phosphorylation by activating PKA. However, ethanol did not affect phosphorylation of NR1 subunits by PKC at serine 896. We conclude that ethanol has the ability to modulate phosphorylation of both NR2 and NR1 subunits and these effects appear to implicate tyrosine phosphatases and PKA, respectively.
Ferrani-Kile
K
K
Division of Pharmacology and Toxicology, College of Pharmacy and the Waggoner Center for Alcohol and Addiction Research, The University of Texas at Austin, 1 University Station, A1915, Austin, TX 78712, USA. ferrani@mail.utexas.edu
Randall
P K
PK
Leslie
S W
SW
D020268:Alcohol-Induced Disorders, Nervous System / Q000201:enzymology* / Q000503:physiopathology; D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000201:enzymology / Q000503:physiopathology; D017868:Cyclic AMP-Dependent Protein Kinases / Q000187:drug effects* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004791:Enzyme Inhibitors / Q000494:pharmacology; D000431:Ethanol / Q000494:pharmacology*; D007150:Immunohistochemistry; D010766:Phosphorylation / Q000187:drug effects; D017027:Protein Tyrosine Phosphatases / Q000187:drug effects* / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000187:drug effects* / Q000378:metabolism; D012694:Serine / Q000378:metabolism; D009435:Synaptic Transmission / Q000187:drug effects* / Q000502:physiology
D004791:Enzyme Inhibitors; C409466:NR1 NMDA receptor; C120997:NR2A NMDA receptor; D016194:Receptors, N-Methyl-D-Aspartate; D000431:Ethanol; D012694:Serine; D017868:Cyclic AMP-Dependent Protein Kinases; D017027:Protein Tyrosine Phosphatases