Elsevier

Brain Research

Volume 546, Issue 2, 19 April 1991, Pages 227-234
Brain Research

Ethanol inhibition of NMDA mediated depolarizations is increased in the presence of Mg2+

https://doi.org/10.1016/0006-8993(91)91486-KGet rights and content

Abstract

The inhibitory potency of ethanol upon excitatory amino acid induced depolarizations of rat hippocampal CA1 pyramidal cells was assessed in the presence and absence of magnesium (Mg2+) using the grease-gap technique. Ethanol shifted theN-methyl-d-aspartate (NMDA) dose-response curves to the right in a non-parallel manner. In the presence of Mg2+, ethanol appeared to be a more effective NMDA antagonist (IC50 47 mM) than in the absence of Mg2+ (IC50 107 mM). The IC50 for ethanol upon non-NMDA mediated CA1 pyramidal cell depolarizations was in excess of 170 mM. These results strongly suggest a preferential inhibitory action of ethanol against NMDA, rather than non-NMDA, mediated responses. Experiments in which ethanol and Mg2+ were covaried indicated that these substances act by two distinct mechanisms to antagonize the action of NMDA. These effects of ethanol, at concentrations which elicit intoxication(< 50mM) but not anesthesia, suggest that the NMDA receptor complex may play an important role in the acute effects of ethanol.

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