Ethanol alters N-methyl-D-aspartate receptor regulation in the hippocampus of adolescent rats

Our laboratory and others have shown that ethanol disrupts hippocampus-associated memory formation in adolescent rats, but the signaling pathway involved remains largely unknown. Phosphorylation of the N-methyl-D-aspartate receptor, particularly the N-methyl-D-aspartate receptor subunit 2B (NR2B), has been implicated in several ethanol effects and in memory formation. The present study investigated the effects of repeated ethanol exposure on the phosphorylation of the NR2B subunit and src protein in the hippocampus of adolescent rats. Rats were treated daily with ethanol or vehicle for 5 consecutive days and sacrificed at several time points after the last treatment. At 30 min postethanol treatment, levels of phosphorylated NR2B and src were significantly elevated; this was the same postethanol time point when adolescent rats showed impairments in their performance of memory tasks. Peak increases in both phosphorylated levels of NR2B and src were seen around 1 h post-treatment, after which levels of both phosphoproteins started to decline. Together, these data suggest that the time-dependent increase in hippocampal phosphorylated NR2B and src levels following repeated ethanol exposure may be responsible for hippocampus-associated memory impairments in adolescent rats.