Neuromelanin in Substantia Nigra Neurons Lacking Tyrosine Hydroxylase

摘要

Immunocytochemical studies of the distribution of tyrosine hydroxylase (TH), the key enzyme in catecholamine synthesis, in neurons of the substantia nigra of human brains (n = 7) were performed, with identification of the locations of melanin in the same cells. The results showed that the substantia nigra contains three types of neurons: neurons containing TH and neuromelanin, neurons containing only neuromelanin, and neurons containing neither TH nor neuromelanin. The existence of a population of neuromelanin-containing neurons lacking TH (accounting for 7–30% of cells) is assessed from the point of view of the involvement of catecholamines and TH in neuromelanin synthesis.