[Glutamatergic regulation of citrulline extracellular level in the nucleus accumbens during acquisition and expression of conditioned emotional response].

In Spregue-Dawley rats, by means of in vivo microdialysis combined with HPLC analysis, it was shown that acquisition and expression of conditioned emotional response increased extracellular level of citrulline: a nitric oxide coproduct, in the nucleus accumbens. Intraaccumbal infusion of MK-801 (100 microM): an NMDA antagonist, markedly attenuated the increase in extracellular citrulline in the n. accumbens produced by acquisition of the response, and completely prevented its conditioned rise observed during expression of the response. The data obtained suggest that, during acquisition and expression of the conditioned emotional response, glutamatergic input to the n. accumbens might act via NMDA receptors to stimulate NO production within this brain area.