Amine accumulation: a possible precursor of Lewy body formation in Parkinson's disease

It is now well recognized that the hypothalamus is an important site of neuropathology in Parkinson's disease (PD). Lewy bodies, a marker of nerve cell degeneration and a pathological hallmark of PD, have been observed frequently in the hypothalamus of PD patients by Lewy (1923) and other investigators and confirmed by more recent systematic studies by Langston & Forno (1978). Both Lewy and Langston & Forno found a predilection of Lewy body formation in specific hypothalamic nuclei with the tuberomammillary, lateral, and posterior areas containing by far the highest average counts per nucleus. Selective vulnerability of the tuberomammillary, lateral, and posterior hypothalamic cell groups to degeneration has been observed also in aging, postencephalitic Parkinsonism, Alzheimer's disease, and schizophrenia. The susceptibility of these particular nuclei to degenerative changes including Lewy body formation is not presently understood nor are the mechanisms by which Lewy bodies are formed in PD and other CNS disorders. Accumulation of amines, a pathological process which follows degeneration of catecholamine-containing neurons in experimental animals, also occurs most frequently in the lateral and posterior hypothalamic areas. In the present communication we propose that in PD, amine accumulation may be a precursor to Lewy body formation and that the susceptibility of certain hypothalamic areas to Lewy body formation may be related to their propensity to accumulate amines. Furthermore, the frequent co-existence of Lewy bodies and Alzheimer's neurofibrillary tangles in the lateral and posterior hypothalamic nuclei suggest that they may share a common pathogenetic etiology. If confirmed, this hypothesis may provide an experimental model by which the formation of Lewy bodies and neurofibrillary tangles may be investigated.