[Dopamine-NO interaction in the nucleus accumbens during stress-induced inhibition of expliratory behavior]

In Sprague-Dawley rats by means of in vivo microdialysis it was shown that stress, evoked by conditioned fear response acquisition, resulted in inhibition of exploratory behavior and produced a reduction of exploration-induced rise in extracellular levels of citrulline (an NO co-product) in the nucleus accumbens which were observed 24 hours after the stress. Intra-accumbal infusion of dopamine D2 receptor antagonist raclopride (10 μM), made after the conditioned fear response acquisition, in 24 hours after the infusion, restore the exploratory behavior and exploration-induced rise of extracellular levels of citrulline in this brain area. The data obtained indicate for the first time that stress-induced inhibition of the exploratory behavior might be mediated by inhibition of the nucleus accumbens nitrergic system occurring under the control of D2 receptors of this brain area.