INDIVIDUAL-DIFFERENCES IN DOPAMINE RELEASE BUT NOT ROTATIONAL BEHAVIOR CORRELATE WITH EXTRACELLULAR AMPHETAMINE LEVELS IN CAUDATE-PUTAMEN IN UNLESIONED RATS

It has been postulated that differences in pharmacokinetics do not con tribute to the well-known individual variability in response to amphet amine (AMPH), but this is yet to be investigated thoroughly. Therefore , rotational behavior of outbred rats (Sprague-Dawley, 4 months old) w as recorded during microdialysis sessions and striatal microdialysate was analyzed concomitantly for AMPH and dopamine concentrations after a single injection of 2.5 mg/kg AMPH SC. Three hours later these rats received three doses of 5 mg/kg AMPH SC (spaced 2 h apart) and their b rain temperature was recorded every 20 min. The most important finding s were: 1) the increase in extracellular dopamine was highly correlate d with the corresponding peak AMPH levels in the microdialysate; 2) th e peak dopamine level in response to 2.5 mg/kg AMPH was predictive of the hyperthermic response observed during 3 x 5 mg/kg AMPH and 3) high versus low rotators differed neither in their AMPH nor in their dopam ine extracellular striatal concentrations.