Experimental Procedures Results and Discussion

Cells in the nervous system (NS) are exposed to a strong and constant production of reactive oxygen and nitrogen species (RS) because of their highly demanding metabolism. This oxidative load is tightly regulated to sustainable limits by an effective array of antioxidant proteins and compounds. However, physiological aging and a number of genetic and environmentally-induced degenerative diseases affect both the production and the clearance of RS. The subsequent oxidative stress (OS) clearly contributes to the pathogenic mechanisms underlying these conditions. As a way of studying the antioxidant mechanisms participating in NS homeostatic regulation, several methods of RS induction have been used. Some of these methods, involving treatments with drugs such as MPTP, maneb and paraquat (PQ; 1,1¢-dimethyl-4,4¢-bipyridinium), in model organisms are able to totally or partially mimic the signs and symptoms of a devastating neurodegenerative process such as Parkinson’s disease (Drechsel and Patel 2008). The extensive work of several groups with these compounds has uncovered the detailed process of the response of the NS to the experimentally-induced OS. The treatment with chronic sublethal doses of these compounds elicits NS specific responses that are generated by the different cell types involved. Early responses to PQ in gene expression