Variability of the mesolimbic neuronal activity in a rat model of depression

The Flinders Sensitive Line of rats is a widely accepted and validated model of depression. These rats demonstrate abnormalities in limbic dopamine neurotransmission, suggesting disturbed neuronal activity in the ventral tegmental area. Interspike interval time series were recorded from the ventral tegmental area of the control Sprague-Dawley and Flinders Sensitive Line rats. These data were analyzed for the variance of interspike interval for each group of animals. We found that FSL rats show a significant decrease in the variance of 0.25-0.5-s-long interspike intervals. Moreover, these abnormalities were normalized following 14-day treatment with desipramine. We suggest that the interspike intervals at this range may have an important role in the information encoding of mesolimbic dopaminergic activity. Impaired variance of the length of interspike intervals in this area may correspond to the pathophysiology of depression, and hence be a possible marker for the analysis of the efficiency of antidepressant treatment.