N-METHYL-D-ASPARTATE-STIMULATED INCREASES IN INTRACELLULAR CALCIUM EXHIBIT BRAIN REGIONAL DIFFERENCES IN SENSITIVITY TO INHIBITION BY ETHANOL

This study compared N-methyl-D-aspartate (NMDA)-stimulated increases i n intracellular calcium in fura-2-loaded neurons dissociated from newb orn rat brainstem (EC(50) in mu M; 6.4), cerebellum (9.5), forebrain ( 6.3), and hippocampus (10.6). Ethanol inhibition of the response to 25 mu M NMDA differed among the regions. The NMDA response in hippocampu s was inhibited by 20 mM ethanol; cortex and cerebellum responses were inhibited by 80 mM ethanol, and no inhibition was seen in the brainst em. Addition of glycine (15 mu M) failed to attenuate ethanol inhibiti on of the NMDA response. These results demonstrate that ethanol inhibi tion of NMDA-stimulated responses varies according to brain region. In contrast to previous findings from this laboratory using dissociated neurons from whole brain, the addition of glycine did not reverse the inhibitory effects of ethanol on NMDA-stimulated responses.