Physiological and pharmacological evidence for a serotonergic projection to the hippocampus.
Rat hippocampal pyramidal cells were studied for their response to serotonin applied iontophoretically and to stimulation of the midbrain raphe nuclei. Ninety-two percent of the cells studied were inhibited by serotonin. Fourty-eight percent of the cells responded by inhibition to dorsal and median raphe stimulation. The inhibitory response to raphe stimulation was absent when the rats were pretreated with p-chlorophenylalanine (PCPA), a serotonin synthesis inhibitor; PCPA effects were alleviated by 5-HTP or 5-HT administration. The response to raphe stimulation was blocked by emthysergide and cyproheptadine. The responses to raphe stimulation were potentiated by chlorimipramine, a serotonin reuptake blocker. These data satisfy several of the criteria required to identify serotonin as the inhibitory neurotransmitter for the raphe-hippocampal pathway
D006916:5-Hydroxytryptophan / Q000494:pharmacology; D008735:5-Methoxytryptamine / Q000494:pharmacology; D000818:Animals; D001640:Bicuculline / Q000494:pharmacology; D002997:Clomipramine / Q000494:pharmacology; D003533:Cyproheptadine / Q000494:pharmacology; D003891:Desipramine / Q000494:pharmacology; D010134:Fenclonine / Q000494:pharmacology; D006624:Hippocampus / Q000502:physiology*; D006897:Hydroxyindoleacetic Acid / Q000494:pharmacology; D007478:Iontophoresis; D008238:Lysergic Acid Diethylamide / Q000494:pharmacology; D008297:Male; D008784:Methysergide / Q000494:pharmacology; D009434:Neural Pathways; D051381:Rats; D011930:Reaction Time; D012154:Reticular Formation / Q000187:drug effects / Q000502:physiology*; D012701:Serotonin / Q000494:pharmacology / Q000502:physiology*; D009435:Synaptic Transmission
D003533:Cyproheptadine; D012701:Serotonin; D008735:5-Methoxytryptamine; D006897:Hydroxyindoleacetic Acid; D008238:Lysergic Acid Diethylamide; D006916:5-Hydroxytryptophan; D002997:Clomipramine; D010134:Fenclonine; D003891:Desipramine; D008784:Methysergide; D001640:Bicuculline