Place conditioning and neurochemical responses elicited by the aftereffect of acute stressor exposure involving an elevated stand

Acute exposure to an elevated stand has been used as an inescapable mild stressor for rats. The present study examined the effects of this stressor using a place conditioning behavioral test and neurochemical assays of dopamine and its metabolite, 3,4-dihydroxyphenylacetic acid (DOPAC), in the medial prefrontal cortex and nucleus accumbens. The behavioral data showed that a conditioned place preference was formed as an aftereffect of the elevated stand stressor. In a separate experiment, neurochemical assay showed an immediate increase of dopamine in the nucleus accumbens after 30 min exposure to the elevated stand stressor. In addition, the DOPAC content in the nucleus accumbens was significantly increased at 30 min after this stressor. No significant change in dopamine or DOPAC levels in the medial prefrontal cortex was detected for up to 60 min after stressor manipulation. These results suggest that an increase in dopamine activity in the nucleus accumbens is involved in the development of conditioned place preference elicited by the aftereffects of the elevated stand stressor.

► A mild stressor was manipulated by placing the rat on an elevated stand.
► The release from this stressor was shown to elicit conditioned place preference.
► The aftereffect of a mild stressor can facilitate place conditioning.
► Dopamine increased in the nucleus accumbens immediately after the stressor exposure.
► Mesolimbic dopamine system is involved in this type of place conditioning.