Qualitative and quantitative analysis of locus coeruleus neurons in Parkinson's disease

Abstract

The analysis of qualitative changes in the locus coeruleus (LC) was performed on brains from 21 cases of Parkinson's disease. Eleven cases were selected for quantitative analysis of the loss of LC noradrenergic pigmented neurons. The qualitative studies revealed uneven dissemination of the noradrenergic cells loss of overall structure of the LC. Few preserved neurons showed degenerative changes. Extracellular neuromelanine granules, traces of dying neurons, were also observed. A weak astro- and microglia proliferation corresponded with neuronal loss. Lewy bodies were found in the LC in all cases. The quantitative analysis revealed that the average loss of adrenergic neurons in the LC accounts for about 70% in relation to the control group. The degenerative changes were observed in the whole LC, but they were most intensive in its caudal and next in the middle segment. The results suggest also that the degenerative process began in the middle segment and then it spread towards caudal segment of the LC as the stages of disease advanced.