Inhibition of Cortical Neurones by Imidazole and Some Derivatives

Systematic tests of imidazole and 15 derivatives, applied by microiontophoresis in anesthetized cats, showed a high inhibitory potency of imidazole-4-acetic and imidazole-4-propionic acids and also of their amyl and propyl esters; but imidazole 4-carboxylic and 1-methylimidazole-4-acetic acids were largely inactive. This order of potency is very different from the relative potencies of imidazole derivatives in facilitating cyclic nucleotide phosphodiesterase activity. It is therefore unlikely that their inhibitory action is simply related to changes in cellular levels of cyclic AMP. The characteristics of this action, including lack of antagonism by bicuculline, are consistent with the possibility that it is mediated by γ-aminobutyric acid receptors.