Giant identified NO-releasing neurons and comparative histochemistry of putative nitrergic systems in gastropod molluscs

Gastropod molluscs provide attractive model systems for behavioral and cell ular analyses of the action of nitric oxide (NO), specifically due to the p resence of many relatively giant identified nitrergic neurons in their CNS. This paper reviews the data relating to the presence and distribution of N O as well as its synthetic enzyme NO synthase (NOS) in the CNS and peripher al tissues in ecologically and systematically different genera representing main groups of gastropod molluscs. Several species (Lymnaea, Pleurobrancha ea, and Aplysia) have been analyzed in greater detail with respect to immun ohistochemical, biochemical, biophysical, and physiological studies to furt her clarify the functional role of NO in these animals. (C) 2000 Wiley-Liss , Inc.