2001 Volume 43 Issue 2 Pages 129-134
We report a reliable 5-min on-line monitoring of dopamine released from the dorsal striatum and the nucleus accumbens of rats using in vivo brain microdialysis. The detection limit for dopamine was approximately 20 fg in a 10-μd injection sample using high-performance liquid chromatography with electrochemical detection set-up. Basal levels of dopamine in the dorsal striatum and the nucleus accumbens 4 h after probe insertion were 2.65±0.30 pg/5 min and 1.57±0.31pg/5 min, respectively, whereas those of 20 h after probe insertion were lower : 0.97±0.21 pg/5 min and 0.51±0.09 pg/5 min, respectively. Infusion of the sodium channel blocker, tetrodotoxin (TTX; 2, uM), essentially suppressed levels of dopamine in both brain areas. At 4 h after probe insertion, TTX perfused for 4 h via dialysis probe reduced levels of dopamine to 0.47±0.08 pg/5 min (80% reduction) in the dorsal striatum and to 0.56±0.19 pg/5 min (65 % reduction) in the nucleus accumbens. At 20 h after probe insertion, a similar TTX perfusion more rapidly reduced levels of dopamine to 0.05±0.01 pg/5 min (95% reduction) in the dorsal striatum and to 0.08±0.01 pg/5 min (85% reduction) in the nucleus accumbens. These results suggest that relatively fast changes in extracellular dopamine levels in these two brain areas can reliably be followed by this in vivo microdialysis technique. (J. Oral Sci. 43, 129-134, 2001)
