Neuromelanin accumulation with age in catecholaminergic neurons from XXXX brainstem.

@entity575 @entity5434 @entity38212 @entity2339 @entity2922 @entity669
@entity38212 (NM) is an auto-oxidation by-product of @entity2922 synthesis which is observed almost exclusively in primates. We have estimated the distribution and the number of NM-positive neurons of the upper brainstem and the degree of their melanization from birth to the onset of senescence in 5 monkeys ( @entity5434 ) aged 0, 1.5, 3.5, 8 and 13 years. Series of sections taken at 640-microns intervals were examined either unstained to detect unstained NM, stained for NM with Masson @entity575 impregnation or processed by @entity669 hydroxylase (TH) immunohistochemistry to analyze catecholaminergic neurons. The proportion of NM-containing cells among TH-positive neurons varied from one catecholaminergic region to another: low in the @entity2339 and central gray substance (cgs); moderate in the cell group A8, and high in the ventral tegmental area (VTA), locus coeruleus (LC) and substantia nigra (SN). TH-positive neurons were detected in the SN, VTA, catecholaminergic cell group A8, LC, cgs and @entity2339 . At birth, although no unstained NM-positive neurons were detected, Masson-stained cells were observed, though only in the LC. At 1.5 and 3.5 years, Masson-positive neurons were observed despite the absence of visible pigment. At 8 and 13 years, unstained NM was present in Masson-positive neurons. The number of unstained NM-positive neurons and Masson-positive neurons and the amount of NM per neuron increased with age in each subregion studied. Nevertheless, some TH-positive neurons were found to be without NM. The data indicate a differential increased NM content with age in the neurons of midbrain catecholaminergic cell groups. However, its functional significance remains to be determined.
