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Saturday, October 4, 2008

Actin depolymerization contributes to ethanol inhibition of NMDA receptors in primary cultured cerebellar granule cells
Alcohol Volume 42, Issue 7, November 2008, Pages 525-539


We have previously reported that a 30 s ethanol (10 and 100 mM) 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 30 s 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 100 mM 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 30 s treatment of either latrunculin A or 100 mM ethanol.

Our observations indicate that ethanol inhibition of NMDAR function may involve perturbation of the actin cytoskeleton.

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