IMMUNOHISTOCHEMICAL DETECTION OF 4-HYDROXYNONENAL PROTEIN ADDUCTS IN PARKINSON DISEASE

There is growing evidence that oxidative stress and mitochondrial resp iratory failure with attendant decrease in energy output are implicate d in nigral neuronal death in Parkinson disease (PD), It is not known, however, which cellular elements (neurons or glial cells) are major t argets of oxygen-mediated damage, 4-Hydroxy-2-nonenal (HNE) was shown earlier to react with proteins to form stable adducts that can be used as markers of oxidative stress-induced cellular damage, We report her e results of immunochemical studies using polyclonal antibodies direct ed against HNE-protein conjugates to label the site of oxidative damag e in control subjects (ages 18-99 years) and seven patients that died of PD (ages 57-78 years), All the nigral melanized neurons in one of t he midbrain sections were counted and classified into three groups acc ording to the intensity of immunostaining for HNE-modified proteins-i. e., no staining, weak staining, and intensely positive staining, On av erage, 58% of nigral neurons were positively stained for HNE-modified proteins in PD; in contrast only 9% of nigral neurons were positive in the control subjects; the difference was statistically significant (M ann-Whitney U test; P < 0.01), In contrast to the substantia nigra, th e oculomotor neurons in the same midbrain sections showed no or only w eak staining for HNE-modified proteins in both PD and control subjects ; young control subjects did not show any immunostaining; however, age d control subjects showed weak staining in the oculomotor nucleus, sug gesting age-related accumulation of HNE-modified proteins in the neuro n, Our results indicate the presence of oxidative stress within nigral neurons in PD, and this oxidative stress may contribute to nigral cel l death.