Glutamate stimulation of acetylcholine release from myenteric plexus is mediated by endogenous nitric oxide.
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.
Milusheva
Elisaveta A
EA
Department Vegetative regulations, Institute of Physiology, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., BL. 23, 1113 Sofia, Bulgaria. eli@bio.bas.bg
Kuneva
Vjara I
VI
Itzev
Dimitar E
DE
Kortezova
Nadejda I
NI
Sperlagh
Beata
B
Mizhorkova
Zlatka N
ZN
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
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