Reduction of rat brain levels of the endogenous dopaminergic proneurotoxins 1,2,3,4-tetrahydroisoquinoline and 1,2,3,4-tetrahydro-beta-carboline by cigarette smoke.

1,2,3,4-Tetrahydroisoquinoline (TIQ) and 1,2,3,4-tetrahydro-beta-carboline (THbetaC) are two endogenous or exogenous dopaminergic proneurotoxicants supposedly involved in the etiology of Parkinson's disease. We investigated whether the chronic administration of a twice daily dose of a cigarette smoke solution might modify the endogenous concentrations of TIQ and THbetaC in rat brain. Using gas chromatography/mass spectrometry (GC-MS) we found a significant reduction in the brain levels of both proneurotoxins after 30 days of treatment. The reduction in the brain levels of both compounds was more significant using Burley rather than Bright tobacco. These results suggest that cigarette smoke may prevent the accumulation of these proneurotoxins in the brain, which corroborate the involvement of the reaction between both TIQ and THbetaC with some components of tobacco smoke as a neuroprotective mechanism for Parkinson's disease.