PARALLEL ALTERATIONS IN MET-ENKEPHALIN AND SUBSTANCE-P LEVELS IN MEDIAL GLOBUS-PALLIDUS IN PARKINSONS-DISEASE PATIENTS

Met-enkephalin (Met-enk) and substance P (SP) were measured by a combi ned high-performance liquid chromatography/radioimmunoanalysis method in medial (GPM) and lateral globus pallidus (GPL) from controls and fr om Parkinson's disease (PD) patients. All patients showed a similar ma rked (> 90%) reduction in dopamine (DA) levels in putamen compared wit h controls. However, based on DA levels in the caudate nucleus, two su bgroups of PD patients were differentiated. In patients with > 80% dec rease in caudate nucleus DA content, there was a three-fold increase i n both Met-enk and SP levels in GPM. In contrast, in patients showing an approximately 50% reduction in DA content in caudate, levels of bot h peptides were markedly reduced (approximately 80%). Met-enk and SP l evels in GPL were unchanged in PD. These results suggest that neurons containing Met-enk and SP projecting to GPM adapt according to the ext ent of degeneration in the substantia nigra in PD.