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Intracerebroventricular Injection of Histamine Induces State-Dependency through H1 Receptors

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The aim of the present study was to investigate whether and by which mechanism; histamine can induce state-dependent retrieval of passive avoidance task. The pre-training or pre-test intracerebroventricular (i.c.v.) injection of histamine (20flg/mouse) impaired retrieval, when it was tested 24 h later. In the animals, which retrieval was impaired due to histamine pre-training administration , pre-test administration of histamine, with the same dose, restored retrieval. The H] blocker, pyrilamine (20 ug/rnouse, i.e.v.), but not the H2 blocker; ranitidine prevented the restoration of retrieval by pre-test histamine. A pre-test administration of histamine H) receptor antagonist, c1obenprobit, also reversed hitamine-induced impairment of memory retention . In conclusion, histamine can induce state-dependent retrieval through the HI receptor HI mechanism.

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