Limbic dopaminergic adaptation to a stressful stimulus in a rat model of depression.

The dopaminergic mesolimbic system has a key role in motivation and reward, and stressful stimuli appear to alter its functionality. Since stress is considered to be one of the primary factors that mediate the expression of depressive behavior, dopamine and its metabolites in the nucleus accumbens of control and Flinders Sensitive Line rats, an animal model of depression, were examined prior to and after a forced swim test. In both types of rats, the levels of dopamine metabolites markedly decreased after the forced swimming, albeit to different extents. In contrast, 60 min after the swim test, dopamine levels were elevated only in the control rats. The accumbal dopaminergic activity is discussed in relation to the behavior of 'depressed' and normal rat lines subjected to a stressful event.