NADPH DIAPHORASE ACTIVITY IN PEPTIDERGIC NEURONS OF THE PARASITIC NEMATODE, ASCARIS-SUUM

The histochemical marker for nitric oxide synthase, NADPH diaphorase, is known to co-localize in mammalian neurones with various classical n eurotransmitters and neuropeptides. The nervous system of the parasiti c nematode Ascaris suum has previously been shown to contain both NADP H diaphorase activity and neuropeptide immunoreactivity. This study ex amined the possibility that NADPH diaphorase and neuropeptide immunore activity may co-exist in the same neurones. Two antisera were used, on e raised to KYSALMFamide, a C-terminal synthetic analogue of SALMFamid e 1 (GFNSALMFamide), and another that recognizes calcitonin-gene-relat ed peptide (CGRP). We provide evidence that in a distinct subset of ne urones in the ventral, dorsal and lateral ganglia NADPH diaphorase sta ining and SALMFamide-like immunoreactivity are co-localized, suggestin g a possible role for nitric oxide in modulating neuropeptide activity in these regions. CGRP-like immunoreactivity was less widely distribu ted, and was not consistently co-localized with NADPH diaphorase.