Studies on male Sprague-Dawley rats using vital intracerebral microdialysis and high-performance liquid chromatography addressed changes in glycine levels in the intercellular space of the nucleus accumbens during forced correction of feeding behavior. The results showed that presentation to food-consuming rats of a tone previously combined with pain stimulation induced increases in extracellular glycine levels in the nucleus accumbens, which was completely prevented by administration of the sodium channel blocker tetrodotoxin (1 microm) into this structure. Isolated presentation of the tone previously combined with pain stimulation and combined presentation of food and a tone not associated with pain stimulation were not accompanied by glycine release. These data provide evidence for the involvement of glycine mechanisms of the nucleus accumbens in processes associated with forced correction of feeding behavior.