Different nicotinic acetylcholine receptor subtypes mediating striatal and prefrontal cortical [3H]dopamine release

Different nicotinic acetylcholine receptor subtypes appear to modulate dopamine release from the striatum and prefrontal cortex. In this study a combination of subtype-selective antagonists and agonists were used to extensively characterize the nAChRs involved in dopamine release from slice preparations of these two brain regions. α-conotoxin-MII inhibited nicotine-evoked [3H]dopamine (DA) release from striatum by 45%, but did not affect cortical dopamine release. Neither methyllycaconitine, α-bungarotoxin, nor α-conotoxin-ImI affected nicotine-evoked [3H]DA release from either striatum or prefrontal cortex. MG 624, a novel selective nAChR antagonist, inhibited cortical [3H]DA by 53%, but had no effect on striatal release. Compared to nicotine, (±)-UB-165 showed less efficacy with respect to dopamine release from striatum, and had no effect on cortical dopamine release. (±)-UB-165-evoked striatal dopamine release was completely blocked by mecamylamine, partially blocked (up to 55%) by α-conotoxin-MII, and unaffected by methyllycaconitine or α-conotoxin-ImI. α4β2* and α6β2β3* nAChRs appear to play a role in striatal dopamine release, whereas α4β2* nAChRs modulate release from prefrontal cortex. α7* nAChRs do not appear to play a role in nAChR-mediated dopamine release from either brain region.