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 neurons. When applied to cultured hippocampal neurons, histamine selectively increased by up to tenfold the amplitude of the component of synaptic transmission that was mediated by N-methyl-D-aspartate (NMDA) receptors. Spontaneous miniature synaptic currents and the current elicited by applied NMDA also were enhanced, indicating that the histamine effect was expressed primarily postsynaptically. These results suggest that histamine may modulate processes involving NMDA receptors, such as the induction of long-term potentiation.