In vitro and in vivo studies investigating possible antioxidant actions ofnicotine: relevance to Parkinson's and Alzheimer's diseases

An inverse relationship appears to exist between cigarette smoking and the risk of Parkinson's and Alzheimer's diseases. Since both diseases are chara cterized by enhanced oxidative stress, we investigated the antioxidant pote ntial of nicotine, a primary component of cigarette smoke. Initial chromato graphic studies suggest that nicotine can affect the formation of the neuro toxin 6-hydroxydopamine resulting from the addition of dopamine to Fenton's reagent (i.e., Fe2+ and H2O2) Thus, under certain circumstances, nicotine can strongly affect the course of the Fenton reaction. In in vivo studies, adult male rats being treated with nicotine showed greater memory retention than controls in a water maze task. However, neurochemical analysis of neo cortex, hippocampus, and neostriatum from these same animals revealed that nicotine treatment had no effect on the formation of reactive oxygen specie s or on lipid peroxidation for any brain region studied. In an in vitro stu dy, addition of various concentrations of nicotine to rat neocortical homog enates had no effect on lipid peroxidation compared to saline controls. The results of these studies suggest that the beneficial/protective effects of nicotine in both Parkinson's disease and Alzheimer's disease may be, at le ast partly, due to antioxidant mechanisms. (C) 1999 Elsevier Science B.V. A ll rights reserved.