title: High-frequency oscillation in the hippocampus of the behaving rat and its modulation by the histaminergic system.
abstract: The histaminergic neurons located in the posterior hypothalamus modulate whole brain activity in a manner dependent on behavioral state. We have investigated their influence on high-frequency oscillation (200-Hz ripples) in the hippocampal CA1 region of freely moving rats. The occurrence of these ripples, assumed to be involved in memory trace formation, was markedly enhanced after injection of the H1-antagonists pyrilamine and ketotifen in a lateral ventricle, indicating a tonic activity of the histaminergic system. The H2- and H3-antagonists cimetidine and thioperamide were ineffective. We suggest a mediation of these effects through blocking the known histaminergic excitation of septal neurons. Histamine administered by the intracerebroventricular route had an inhibitory action on ripples. H1-receptor activation, which has been shown to inhibit learning and memory, thus shifts hippocampal activity away from high-frequency oscillation toward theta activity.
authors.affiliation: Heinrich Heine University, Düsseldorf, Germany.
authors.forename: A
authors.initials: A
authors.lastname: Knoche
authors.forename: H
authors.initials: H
authors.lastname: Yokoyama
authors.forename: A
authors.initials: A
authors.lastname: Ponomarenko
authors.forename: C
authors.initials: C
authors.lastname: Frisch
authors.forename: J
authors.initials: J
authors.lastname: Huston
authors.forename: H L
authors.initials: HL
authors.lastname: Haas
mesh_terms: D000818:Animals; D001522:Behavior, Animal / Q000502:physiology*; D004305:Dose-Response Relationship, Drug; D004569:Electroencephalography / Q000187:drug effects; D004576:Electromyography; D004594:Electrophysiology; D006120:Grooming / Q000187:drug effects; D006624:Hippocampus / Q000502:physiology*; D006632:Histamine / Q000502:physiology*; D006633:Histamine Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D006635:Histamine H2 Antagonists / Q000494:pharmacology; D007276:Injections, Intraventricular; D008297:Male; D008568:Memory / Q000187:drug effects; D009043:Motor Activity / Q000187:drug effects; D051381:Rats
chemical_list: D006633:Histamine Antagonists; D006635:Histamine H2 Antagonists; D006632:Histamine