Psychological stress selectively increases extracellular dopamine in the 'shell', but not in the 'core' of the rat nucleus accumbens: a novel dual-needle probe simultaneous microdialysis study

In order to compare psychological stress-induced dopamine (DA) release in t wo subterritories (e.g. shell and core) of the nucleus accumbens of the sam e animal, a novel dual-needle microdialysis probe has been developed. The t wo needles were placed in the ipsilateral shell and core subterritories of the nucleus accumbens under pentobarbital anesthesia and 24 h later the mic rodialysis was started. Basal DA output was not significantly different bet ween the shell and the core. Psychological stress for 20 min significantly increased extracellular DA levels in the shell of the nucleus accumbens, ho wever, the levels of dopamine remained almost unaltered in the core. This f inding suggests that DA transmission in the shell of the nucleus accumbens was selectively activated during psychological stress, and that the shell p lays an important role in emotional responses. The results further show tha t microdialysis using the novel dual-needle probe could be very useful to d ifferentiate neurochemical changes occurring in neighboring areas in the br ain. (C) 1999 Elsevier Science Ireland Ltd. All rights reserved.