The present results demonstrate that chronic nicotine treatment can in part protect against mechanically-induced and neurotoxin-induced degeneration of nigrostriatal DA neurons. These results indicate that in sufficient doses chronic treatment with nicotine may be considered in the pharmacological treatment of Parkinson's disease. It remains to be demonstrated whether these protective actions can be extended to include also other injured neurons such as the cholinergic neurons, known to be severely affected in Alzheimer's disease.