Extracellular Citrulline Levels in the Nucleus Accumbens during Feeding Behavior

Abstract

Intracerebral microdialysis and high-performance liquid chromatography with electrochemical detection were used in studies on Sprague-Dawley rats to demonstrate that the consumption of a novel foodstuff did not lead to any changes in extracellular levels of citrulline (a coproduct of NO synthesis) in the medial part of the nucleus accumbens. In contrast, refusal to consume a novel foodstuff was accompanied by an increase in the extracellular citrulline level in this structure, this increase being completely prevented by injection of the neuronal NO synthase inhibitor 7-nitroindazole (0.5 mM) into the nucleus accumbens. These data are the first showing that refusal of a novel foodstuff (but not its consumption) is characterized by activation of neuronal NO synthase in the medial part of the nucleus accumbens, leading to increases in the cell citrulline level and, probably, increased NO production in this part of the brain.