ALTERATIONS IN PEPTIDE LEVELS IN PARKINSONS-DISEASE AND INCIDENTAL LEWY BODY DISEASE

The levels of the neuropeptides Met- and Leu-enkephalin (MET-ENK, LEU- ENK), substance P and neurotensin were measured by a combined high per formance liquid chromatography/radioimmunoassay (HPLC/RIA) method in p ost-mortem samples of basal ganglia from Parkinson's disease patients, incidental Lewy body disease patients (pre-symptomatic Parkinson's di sease) and matched controls. Dopamine (DA) levels were reduced in the caudate nucleus and putamen in Parkinson's disease, but unaltered in i ncidental Lewy body disease. The levels of MET-ENK were reduced in the caudate nucleus, putamen and substantia nigra in Parkinson's disease. Met-enkephalin levels were reduced in the caudate nucleus and in the putamen in incidental Lewy body disease. Leu-enkephalin levels were de creased in the putamen and were undetectable in the substantia nigra i n Parkinson's disease. Leu-enkephalin levels were unchanged in inciden tal Lewy body disease, although there was a tendency to a reduction in putamen. Substance P levels were reduced in the putamen in Parkinson' s disease. No significant changes in substance P content were observed in incidental Lewy body disease were not altered significantly, but t ended to parallel the changes in Parkinson's disease. The changes in b asal ganglia peptide levels in incidental Lewy body disease generally followed a trend similar to those seen in Parkinson's disease, but wer e less marked. This suggests that they are an integral part of the pat hology of the illness and not secondary to DA neuronal loss or a conse quence of prolonged drug therapy.