ACTIONS OF NITRIC-OXIDE AND EXPRESSION OF THE MESSENGER-RNA ENCODING NITRIC-OXIDE SYNTHASE IN RAT VAGAL AFFERENT NEURONS

The present study has investigated whether nitric oxide (NO) is involv ed in neurotransmission of rat vagal afferent neurons. The diethylamin e-NO complex (diethylamine-NO, 10-100 mu M) and S-nitroso-N-acetylpeni cillamine (3-100 mu M) both elicited a concentration-dependent depolar isation of the isolated rat nodose ganglion preparation. Pre-treatment with 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ, 300 nM), 6-(ph enylamino)-5,8-quinolinedione (LY83,583, 30 mu M) and Methylene blue ( 100 mu M) all caused a significant shift to the right in the concentra tion-response curve to diethylamine-NO. Incubation of rat nodose gangl ion sections with a S-35-labeled antisense oligonucleotide to neuronal NO synthase resulted in visualisation of the mRNA encoding NO synthas e over vagal afferent perikarya. The anatomical findings, therefore, s uggest that a number of rat vagal afferent perikarya possess the abili ty to produce the enzyme required for the biosynthesis of NO. Collecti vely, these data suggest that NO may be functionally important as a ne uromodulator of rat vagal afferent neurons.