Effects of salient environmental stimuli on extracellular adenosine levels in the rat nucleus accumbens measured by in vivo microdialysis

Abstract

In the nucleus accumbens (NAc), the neuromodulator adenosine plays a major role in control of behaviour. The NAc subserves behaviour governed by salient stimuli in the environment, however, it is unknown whether such stimuli and the behavioural effects elicited are associated with changes in NAc extracellular adenosine levels. In order to further characterise the neuromodulatory actions of adenosine, the present study investigated for the first time the effects of four prototypical stimuli known to involve NAc processing on extracellular levels of adenosine in the NAc. Using in vivo microdialysis, the following stimuli were examined: (1) an appetitive, unfamiliar stimulus (palatable food), (2) an appetitive, familiar stimulus (standard laboratory food), (3) an aversive stimulus (handling) and (4) a novelty stimulus (cage change). Results revealed that neither of these stimuli significantly changed extracellular adenosine levels in the NAc. These findings demonstrate that NAc extracellular adenosine is not responsive to a number of prototypical salient stimuli in the environment. Thus the data provide no clues to suggest that transient changes of extracellular adenosine in the NAc modulate behavioural responses governed by these stimuli.