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| euroanatomical studies have revealed a direct hypothalamocerebellar histaminergic pathway, and our previous works have demonstrated an excitatory effect of histamine on granule and Purkinje cells of the cerebellar cortex. In this study, we further investigated the effect of histamine on the neuronal firing of cerebellar interpositus nucleus (IN) by using the cerebellar slice preparations. Eighty-seven IN cells were recorded from 38 slices. The vast majority of the cells responded to histamine stimulation with an excitatory response (79/87, 90.8%), and the rest of them showed no reaction (8/87, 9.2%). The histamine-induced excitation was not blocked by application of low-Ca2+/high-Mg2+ medium (n=8), supporting a direct postsynaptic action of histamine. The histamine H2 receptor antagonist ranitidine effectively blocked the excitatory response of IN cells to histamine (n=23), but the histamine H1 receptor antagonist triprolidine could not significantly block the histamine-induced excit |
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| Keywords:Histamine; Histamine receptors; Cerebellar interpositus nucleus; Hypothalamocerebellar histaminergic fibers |
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