Experiment 7: In Vivo Brain Microdialysis

Microdialysis procedures used in the present experiments are the same as published before (Tanda et al, 2005). Microdialysis probes were prepared in the laboratory and had an active dialyzing surface of 1.8–2.0 mm (Tanda et al, 2005). Probes were surgically implanted into the NAc (according to the coordinates: anterior +2.0 mm, lateral ±1.0 mm from bregma, vertical −7.9 mm from dura) under a mixture of ketamine and xylazine anesthesia as described previously (Tanda et al, 2005).

Experiments were performed on freely moving rats, ∼22–24 h after the probe implantation. Artificial cerebrospinal fluid was perfused into the NAc and dialysates (10 μl) were sampled every 10 min and then immediately analyzed. Results are expressed as the percentage of the amount of DA in 10 min basal dialysate samples, calculated as means of DA values. After reaching stable DA values (2–4 consecutive samples, <10% variability), rats were treated with one dose of JJC8-016 (10 and 30 mg/kg, i.p.), and sampled every 10 min, for the first 2 h and every 20 min thereafter for a maximum of 3 h. Detection of DA in dialysate samples was accomplished by HPLC coupled with a coulometric detector (5200a Coulochem III, ESA, Chelmsford, MA), and cell potentials were set at +125 mV (oxidation) and −125 mV (reduction).