Actin depolymerization contributes to ethanol inhibition of NMDA receptors in primary cultured cerebellar granule cells.
We have previously reported that a 30s ethanol (10 and 100mM) pre-exposure significantly enhanced EtOH inhibition of N-methyl-d-aspartate (NMDA-induced currents)-induced peak currents in primary cultured cerebellar granule cells (CGCs). The purpose of this study was to determine if intracellular factors play a role in ethanol pre-exposure-enhanced inhibition of NMDA-induced currents and if so, to identify the intracellular target(s) mediating this effect. Ethanol pre-exposure-enhanced inhibition was reduced when ethanol was present intracellularly prior to the initiation of the pretreatment protocol. Similar to results acquired with the whole-cell configuration, ethanol pre-exposure-enhanced inhibition of NMDA-induced currents was also observed in the perforated patch-clamp mode. Collectively, these results suggest an intracellular target not easily dialyzed from the cell. Perturbation of the actin cytoskeleton was responsible for the ethanol pre-exposure-enhanced inhibition of NMDA-induced currents was supported by the observation that the intracellular presence of the actin stabilizer phalloidin prevented ethanol pre-exposure-enhanced inhibition. Similar to the effects of ethanol, the depolymerizing agent latrunculin A inhibited NMDA-induced currents after a 30s pretreatment exposure with full recovery of receptor function after washout of the drug. Furthermore, latrunculin A occluded the enhanced inhibition of NMDA-induced currents by ethanol pre-exposure for both 10 and 100mM ethanol. The microtubule depolymerizing agent taxol had no affect on ethanol pretreatment-enhanced inhibition of NMDA-induced currents. Confocal microscopy with phalloidin-FITC indicated that F-actin filaments in neurites were depolymerized after a 30s treatment of either latrunculin A or 100mM ethanol. Our observations indicate that ethanol inhibition of NMDAR function may involve perturbation of the actin cytoskeleton.
Popp
R Lisa
RL
Department of Pharmacology and Neuroscience, Texas Tech University Health Sciences Center, Lubbock, TX 79430-0002, USA. lisa.popp@ttuhsc.edu
Dertien
Janet S
JS
D051339:Actin Depolymerizing Factors / Q000378:metabolism; D000199:Actins / Q000378:metabolism*; D000818:Animals; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism*; D000431:Ethanol / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors* / Q000502:physiology
D051339:Actin Depolymerizing Factors; D000199:Actins; D016194:Receptors, N-Methyl-D-Aspartate; D000431:Ethanol
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