Histamine H3-receptor activation inhibits acetylcholine release from the guinea pig myenteric plexus.
The role of histamine H3-receptors in the control of acetylcholine release from peripheral cholinergic neurons was evaluated in the isolated guinea pig ileum, previously loaded with 3H-choline. When tested in the presence of H1- and H2-blockade, histamine (0.1-100 mumol/l) and (R) alpha-methylhistamine (0.01-1 mumol/l) dose-dependently reduced the electrically-evoked choline outflow, with (R) alpha-methylhistamine being a partial agonist. Selective H3-receptor blocking drugs, thioperamide (0.1 mumol/l) and impromidine (0.1 mumol/l) reversed the histamine-induced inhibitory effect. These data suggest that intestinal cholinergic nerves are endowed with histamine H3-receptors whose activation produces an inhibitory effect upon acetylcholine release. The practical implications of these findings are obvious.
Poli
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E
Institute of Pharmacology, University of Parma, Ospedale Maggiore, Italy.
Stark
H
H
Bertaccini
G
G
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D004558:Electric Stimulation; D006146:Guanidines / Q000494:pharmacology; D006168:Guinea Pigs; D006632:Histamine / Q000494:pharmacology; D006633:Histamine Antagonists; D007082:Ileum / Q000294:innervation; D007093:Imidazoles / Q000494:pharmacology; D017446:Impromidine; D008761:Methylhistamines / Q000494:pharmacology; D009197:Myenteric Plexus / Q000187:drug effects / Q000378:metabolism*; D010880:Piperidines / Q000494:pharmacology; D011968:Receptors, Histamine / Q000502:physiology*; D018100:Receptors, Histamine H3; D014316:Tritium
D006146:Guanidines; D006633:Histamine Antagonists; D007093:Imidazoles; D008761:Methylhistamines; D010880:Piperidines; D011968:Receptors, Histamine; D018100:Receptors, Histamine H3; D014316:Tritium; C069357:alpha-methylhistamine; D006632:Histamine; D017446:Impromidine; C052075:thioperamide; D000109:Acetylcholine