Exposure of a 'witness rat' to one treated with beta-carboline FG 7142 does not increase dopamine turnover in the medial prefrontal cortex of the 'witness rat'.

A method for selectively activating the dopaminergic field of the prefrontal cortex would be highly useful for studies of mesocortical dopamine systems. When a rat ('witness' rat) is exposed to a rat that is undergoing footshock, prefrontocortical dopamine metabolism is selectively increased in the witness rat. Since the anxiogenic beta-carboline FG 7142 mimics many of the effects of footshock, we hypothesized that exposure of a witness-rat to a rat treated with FG 7142 would also increase dopamine metabolism in the prefrontal cortex. We found that while as expected, FG 7142 itself increased prefrontal cortex dopamine metabolism, there was no significant change in dopamine metabolism in the witness rat. Thus exposure to a rat treated with FG 7142 does not selectively activate the mesocortical dopamine system.