NADPH-diaphorase and other neuronal markers in nerves and ganglia supplying the guinea-pig vas deferens

Enzyme histochemistry, in combination with immunohistochemistry was used to establish the neurochemistry of neurons in the vas deferens and pelvic ganglia of the guinea-pig. Nerve fibres characterised by reactivity for reduced nicotinamide adenine dinucleotide phosphate (NADPH)-diaphorase reactivity formed a dense network in the lamina propria and circular muscle layer of the vas deferens, but were very sparse in the longitudinal muscle layer of the vas deferens. NADPH-diaphorase reactivity was also present in nerve fibres forming a dense perivascular plexus in many of the arteries in the pelvic region and in some of the endothelial cells, especially near the origin of the capillaries. Nerves with vasoactive intestinal polypeptide (VIP)-immunoreactivity had a similar distribution to NADPH-diaphorase reactive nerves. Tyrosine hydroxylase (TH)-immunoreactive nerve fibres were found in both muscle layers of the vas deferens. There was no coexistence of VIP- and TH-immunoreactivities in nerve fibres in the vas deferens. In the anterior pelvic ganglia, the origin of the nerve fibres in the vas deferens, several classes of neurons could be identified by the presence or absence of the reactivity for NADPH-diaphorase and immunoreactivity for VIP and TH. Neurons containing both VIP and NADPH-diaphorase reactivity accounted for 40% of neurons in the ganglia. Neurons with VIP-immunoreactivity but not NADPH-diaphorase reactivity accounted for 6%. TH-immunoreactive neurons accounted for 22% of neurons in the anterior pelvic ganglia. Very rare cells (< 1%) contained both VIP- and TH-immunoreactivities. The remaining neurons, which were not labelled by any of these markers, comprised 31% of neurons in anterior pelvic ganglia. These results demonstrate the existence of NADPH-diaphorase reactivity in neurons containing VIP-immunoreactivity, thus suggest that nitric oxide may be a neurotransmitter in guinea-pig vas deferens, especially in the circular muscle layer, in the arteries, and in other pelvic organs innervated by pelvic ganglia.