Dynorphin levels in parkinsonian patients: Leu5-enkephalin production from either proenkephalin A or prodynorphin in human brain.

When measured in postmortem parkinsonian brains, dynorphin levels were unchanged, as compared to control brains, in mesencephalic, striatal and corticolimbic areas. A significant reduction in Leu5-enkephalin and Met5-enkephalin levels had been previously observed in the pallidum and putamen whereas only Met5-enkephalin concentrations were decreased in the substantia nigra of parkinsonian brains. These data suggest that L-Enk could be generated either from proenkephalin A in the striatal areas or from prodynorphin in the nigral areas.