Research Article

Distribution of nitric oxide synthase immunoreactivity in the nervous system and peripheral tissues of Schistosoma mansoni

A. B.  KOHN  a1, L. L.  MOROZ  a1 a2, J. M.  LEA  a1 and R. M.  GREENBERG  a1 a2 c1
a1 Whitney Laboratory, University of Florida, 9505 Ocean Shore Blvd, St Augustine, FL 32086, USA
a2 Department of Neuroscience, University of Florida, 9505 Ocean Shore Blvd, St Augustine, FL 32086, USA

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The distribution of nitric oxide synthase (NOS) immunoreactivity and putative NOS activity in adult Schistosoma mansoni was analysed using 3 different types of NOS antibodies and NADPH-diaphorase histochemistry. Although potential involvement of the gaseous radical nitric oxide (NO) in host response to infection by schistosomes has been suggested, there is little or no information available regarding the role, or even the presence, of the NO pathway in schistosomes themselves. Here, we demonstrate that antibodies against neuronal NOS (nNOS) and inducible NOS (iNOS) isoforms stain adult worms with distinctive patterns; anti-endothelial NOS (eNOS) shows no selective labelling. nNOS-like immunoreactivity is found in the main nerve cords and the peripheral nervous system. Putative sensory neurons with apical neuronal processes leading to the tegument of male worms are also immunoreactive for nNOS. Anti-iNOS labels a variety of predominantly non-neuronal tissues, showing intense labelling at or near the surface of the worm and in components of the gastrointestinal tract. The distribution of NADPH-diaphorase reactivity (a histochemical marker of NOS), is generally similar to the pattern of NOS immunoreactivity, including labelling of neuronal-like cells as well as developing eggs. These results suggest that an NOS-like enzyme is present in S. mansoni, and indicate potential roles for the different NOS isoforms in neuronal signalling, reproduction and development.

(Received May 7 2000)
(Revised July 31 2000)
(Accepted August 1 2000)

Key Words: Schistosoma mansoni; nitric oxide; nitric oxide synthase; NADPH-diaphorase; platyhelminths; sensory systems.

c1 Corresponding author: Whitney Laboratory, 9505 Ocean Shore Blvd, St Augustine, FL 32086, USA. Tel: +904 461 4026. Fax: +904 461 4008. E-mail: