EFFECTS OF PUTATIVE COGNITION ENHANCERS ON THE NMDA RECEPTOR BY [H-3]MK801 BINDING

Piracetam, aniracetam, and D-cycloserine were tested for their ability to reduce inhibition of [H-3]MK801 (dizocilpine) binding by 100 mu M kynurenate. Piracetam (100 mu M-1 mM) failed to reduce inhibition by k ynurenate but stimulated [3H]MK801 binding in the absence of kynurenat e. In contrast, D-cycloserine (30 mu M-1 mM) and aniracetam markedly r educed this inhibition by kynurenate. Thus, cognition enhancers might function via at least some subtypes of NMDA receptors.