NADPH-DIAPHORASE ACTIVITY IN THE VAGAL AFFERENT PATHWAY OF THE DOGFISH, TRIAKIS-SCYLLIA

Nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase activit y was examined in the cranial sensory ganglia and brainstem of the ban ded dogfish, Triakis scyllia. Positive neurons were found in the vagal sensory ganglion projecting to the coelomic organs, but not in those projecting to the gills or the lateral line organs. Nerve terminals in the vagal lobe were also positive. No positive neurons were found in the glossopharyngeal, facial, or trigeminal sensory gang(ia. These res ults suggest that use of nitric oxide in the vagal sensory transmissio n from the coelomic organs may have been maintained in the evolutionar y process from fish to mammals. (C) 1997 Elsevier Science Ireland Ltd.