title: Glutamate stimulation of acetylcholine release from myenteric plexus is mediated by endogenous nitric oxide.
abstract: Glutamate was found to be an excitatory neurotransmitter in the enteric nervous system. Although several lines of evidence indicate a role of glutamate in the regulation of gut motility and secretion the physiological significance of glutamatergic transmission is not clear yet. We studied the effect of glutamate on [3H]acetylcholine release and nicotinamide adenine dinucleotide phosphate-diaphorase staining in longitudinal muscle strips with attached myenteric plexus of guinea pig ileum. L-glutamate (100 microM) significantly enhanced both the evoked [3H]acetylcholine release and the optical density of nicotinamide adenine dinucleotide phosphate-diaphorase positive neurones, i.e. the intensity of staining. The non-competitive N-methyl-D-aspartate receptor antagonist MK-801 (3 microM) abolished the stimulatory effect of L-glutamate on acetylcholine efflux. Similarly, the nitric oxide synthase inhibitor N(omega)-nitro-L-arginine (100 microM) significantly reduced the effect of L-glutamate on [3H]acetylcholine release and nicotinamide adenine dinucleotide phosphate-diaphorase staining. Our data suggest that endogenous nitric oxide seems to mediate the stimulatory effect of glutamate on acetylcholine release from guinea pig myenteric neurons.
authors: Department Vegetative regulations, Institute of Physiology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., BL. 23, 1113 Sofia, Bulgaria. eli@bio.bas.bg
authors: Elisaveta A
authors: EA
authors: Milusheva
authors: Vjara I
authors: VI
authors: Kuneva
authors: Dimitar E
authors: DE
authors: Itzev
authors: Nadejda I
authors: NI
authors: Kortezova
authors: Beata
authors: B
authors: Sperlagh
authors: Zlatka N
authors: ZN
authors: Mizhorkova
mesh_terms: D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D016291:Dizocilpine Maleate / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D018698:Glutamic Acid / Q000494:pharmacology*; D006168:Guinea Pigs; D006651:Histocytochemistry; D007082:Ileum / Q000187:drug effects / Q000294:innervation; D066298:In Vitro Techniques; D008297:Male; D009197:Myenteric Plexus / Q000187:drug effects / Q000378:metabolism*; D009252:NADPH Dehydrogenase / Q000378:metabolism; D009434:Neural Pathways / Q000502:physiology; D009569:Nitric Oxide / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D019335:Nitroarginine / Q000494:pharmacology; D017470:Receptors, Glutamate / Q000187:drug effects; D013268:Stimulation, Chemical; D009435:Synaptic Transmission / Q000502:physiology
chemical_list: D004791:Enzyme Inhibitors; D018691:Excitatory Amino Acid Antagonists; D017470:Receptors, Glutamate; D019335:Nitroarginine; D009569:Nitric Oxide; D018698:Glutamic Acid; D016291:Dizocilpine Maleate; D019001:Nitric Oxide Synthase; D009252:NADPH Dehydrogenase; D000109:Acetylcholine