ENHANCEMENT BY HISTAMINE OF NMDA-MEDIATED SYNAPTIC TRANSMISSION IN THE HIPPOCAMPUS

Histamine is a neuromodulator in the brain, and the hippocampus is one of the regions of the brain that is innervated by histaminergic neuro ns. When applied to cultured hippocampal neurons, histamine selectivel y increased by up to tenfold the amplitude of the component of synapti c transmission that was mediated by N-methyl-D-aspartate (NMDA) recept ors. Spontaneous miniature synaptic currents and the current elicited by applied NMDA also were enhanced, indicating that the histamine effe ct was expressed primarily postsynaptically. These results suggest tha t histamine may modulate processes involving NMDA receptors, such as t he induction of long-term potentiation.