STRIATAL EXPRESSION OF SUBSTANCE-P AND METHIONIN-ENKEPHALIN GENES IN PATIENTS WITH PARKINSONS-DISEASE

The striatal expression of substance P (SP) and methionin-enkephalin ( met-enk) genes was studied post mortem by in situ hybridization in pat ients with Parkinson's disease and a group of control subjects. No sig nificant difference in striatal expression of these two neuropeptide m essenger RNAs (mRNAs) was found in the patients compared with control subjects. This contrasts with animal models of parkinsonism, where exp ression of SP mRNA is decreased and met-enk mRNA increased. Possible e xplanations include: (1) compensatory mechanisms, which may develop du ring the long term evolution of Parkinson's disease; (2) normalized ex pression of the two genes resulting from chronic L-DOPA therapy.