10distribution of NADPH-diaphorase reactivity and effects of nitric oxide on feeding and locomotory circuitry in the pteropod mollusc, Clione limacina

The action of nitric oxide (NO) and the distribution of putative nitric oxi de synthase- containing cells in the pelagic pteropod mollusc Clione limaci na were studied using nicotinamide adenine dinucleotide phosphate diaphoras e (NADPH-d) histochemistry and conventional microelectrode techniques in th e isolated central nervous system and in semi-intact preparations. The majo rity of NADPH-d-reactive neuronal somata were restricted to the cerebral ga nglia. The labeled cells were small in diameter (20-30 mum) and were locate d in the medial areas of the ganglia. A pair of symmetrical neurons was fou nd in the peripheral "olfactory organ." NADPH-d-reactive non-neuronal cells were detected in the periphery and were mainly associated with secretoryli ke cells and organs of the renopericardial system. The NO donor, diethylami ne NO complex sodium salt (10-100 muM), activated neurons from both feeding and locomotory circuits. The cGMP analog, 8-Br-cGMP, mimicked the effects of NO on neurons. We suggest that NO is an endogenous neuromodulator involv ed in the control of some aspects of feeding and locomotor behavior of Clio ne. (C) 2000 Wiley-Liss, Inc.