Effect of histamine on the hippocampal neurons in guinea-pigs

Histamine produced an excitatory effect on CA3 pyramidal cells in hippocampal slices of guinea-pigs. The amplitude of population spikes and EPSPs was augmented by histamine at concentrations of 10(-7) to 10(-6) M. Cimetidine but not pyrilamine prevented the stimulatory effect. The histamine effect was mimicked by dimaprit but not by 2-pyridylethylamine. It is concluded that histamine has a facilitatory influence on the hippocampal excitatory system via H2 receptor.