REPEATED COCAINE AND STRESS INCREASE DOPAMINE CLEARANCE IN THE RAT MEDIAL PREFRONTAL CORTEX

The effects of repeated footshock stress or cocaine on the kinetics of dopamine clearance in the medial prefrontal cortex (mPFC) were measur ed by rotating disk electrode voltammetry (RDEV). Five groups of rats were used: animals were either naive (non-handled), pre-treated with f ive daily saline (1 ml/kg i.p.) or cocaine (15 mg/kg i.p.) injections, or pre-treated with five daily 20-min sessions of sham shock or foots hock (0.05 mA/200 ms/s). Dopamine clearance was measured after a 1-wee k withdrawal period. No difference in K-m values was present among the treatment groups, with the mean K-m value at approximate to 0.5 mu M for all groups. However, V-max values were approximate to 50% higher i n daily sham shock-, footshock-and cocaine-pre-treated animals compare d to naive rats. The increased ability to remove dopamine in these ani mals suggests that altered dopamine clearance may serve an adaptive me chanism in the mPFC. (C) 1997 Elsevier Science B.V.