Minor alkaloids of tobacco release [³H]dopamine from superfused rat striatal slices

In addition to S(-)-nicotine, several minor tobacco alkaloids ((±)-nornicotine, anabaseine, S(-)-anabasine, and S(-)-N-methylanabasine) are present in tobacco smoke. This study demonstrates that these alkaloids increase fractional ³H release in a concentration-dependent manner from rat striatal slices preloaded with [³H]dopamine, with desensitization of this response. The rank order of EC₅₀ values was S(-)-nicotine (3.0 ± 2.2 μM) > (±)-nornicotine (6.7 ± 2.1 μM) > anabaseine (15.4 ± 6.1 μM) = S(-)-N-methylanabasine (16.3 ± 4.7 μM) = S(-)-anabasine (19.3 ± 3.2 μM). The alkaloids did not modulate fractional ³H release evoked by electrical-field depolarization. Thus, minor tobacco alkaloids may contribute to the apparent neuroprotective effects of smoking in neurodegenerative diseases.