Nitric oxide generation around buccal ganglia accompanying feeding behavior in the pond snail, Lymnaea stagnalis

Although there are many lines of evidence for both the presence of nitric o xide synthase (NOS) in the central nervous system (CNS) and the effects of NO on activating and modulating the feeding circuit in Lymnaea stagnalis, t here has been no direct evidence that NO generation in the CNS accompanies feeding behavior. In the present study, we used a NO specific electrode to measure the increase in NO concentration around the buccal ganglia when the lips of semi-intact preparations of L. stagnalis were stimulated by sucros e. The NO concentration of the buccal ganglia was significantly increased b y an application of sucrose to the lips. A NO scavenger and a NOS inhibitor suppressed this increase in NO concentration. A pair of putative NO-genera tive neurons in the buccal ganglia, the B2 cells, are active during the int er-feeding phase, and the bursting of the B2 cell elicited by sucrose appli cation starts simultaneously with the feeding response. The rhythmic pulses of NO generation corresponded well with the rhythmic bursting of the B2 ce lls, which itself corresponds to the 'fictive feeding response'. The presen t data provide the first direct evidence that NO is generated in the buccal ganglia of L, staganalis and is involved in a specific behavior such as Fe eding. (C) 2000 Elsevier Science Ireland Ltd and the Japan Neuroscience Soc iety. All rights reserved.