Table 2.

Effect of nicotine and/or MPTP treatments on evoked dopamine release levels

Striatal regionTreatment groupMaximal nAChR-mediated dopamine release (cpm/mg protein)
Totalα4*α6*
Medial caudateControl6769 ± 10831974 ± 3064825 ± 799
Nicotine7001 ± 7962845 ± 1025021 ± 698
MPTP7344 ± 11001834 ± 3205555 ± 849
MPTP + nicotine5941 ± 4932240 ± 2083876 ± 366
Lateral caudateControl5024 ± 9921497 ± 3063681 ± 709
Nicotine4522 ± 13051811 ± 4432756 ± 624
MPTP2826 ± 575574 ± 1912305 ± 408
MPTP + nicotine2383 ± 467863 ± 2201594 ± 340
Ventral putamenControl7287 ± 6021675 ± 2005636 ± 459
Nicotine3820 ± 8621331 ± 1503182 ± 703
MPTP8373 ± 12182839 ± 4296127 ± 858
MPTP + nicotine6102 ± 8181996 ± 2584015 ± 622
Dorsal putamenControl3721 ± 394877 ± 1973010 ± 238
Nicotine3115 ± 5181062 ± 1941899 ± 319
MPTP2589 ± 602714 ± 2372043 ± 418
MPTP + nicotine1814 ± 508652 ± 2521323 ± 296

  • Animals were given nicotine in the drinking water and subsequently administered MPTP, with nicotine treatment continued until the animals were killed. Nicotine-evoked dopamine release (Rmax) was then determined in the absence (Total) and presence of 50 nm α-conotoxinMII (α4* nAChR component). The difference between total release and that occurring in the presence of α-conotoxinMII was defined as the α6* nAChR component. Each value represents the mean ± SEM of five to seven animals. These values were used to calculate nicotine-evoked fractional [3H]dopamine release or release from residual terminals, which represents maximal evoked dopamine release (Rmax) divided by dopamine transporter values (Table 1) as described previously (Snyder et al., 1990).