Histamine ameliorates spatial memory deficits induced by MK-801 infusion into ventral hippocampus as evaluated by radial maze task in rats

Abstract

Aim: To investigate the role of histamine in memory deficits induced by MK-801 infusion into the ventral hippocampus in rats. Methods: An 8-arm radial maze (4 arms baited) was used to assess spatial memory. Results: Bilateral ventral intrahippocampal (ih) infusion of MK-801 (0.3 μg/site), an N-methyl-D-aspartate (NMDA) antagonist, impaired the retrieval process in both working memory and reference memory. Intrahippocampal injection of histamine (25 or 50 ng/site) or intraperitoneal (ip) injection of histidine (25, 50 or 100 mg/kg) markedly ameliorated the spatial memory deficits induced by MK-801. Both the histamine H1 antagonist pyrilamine (0.5 or 1.0 μg/site, ih) and the H2 antagonist cimetidine (2.5 μg/site, ih) abolished the ameliorating effect of histidine (100 mg/kg, ip) on reference memory deficits, but not that on working memory deficits induced by MK-801. Conclusion: The results indicate that histamine in the ventral hippocampus can ameliorate MK-801-induced spatial memory deficits, and that histamine's effect on reference memory is mediated by postsynaptic histamine H1 and H2 receptors. ©2005 CPS and SIMM.