CYTOCHROME-C-OXIDASE DEFECTS OF THE HUMAN SUBSTANTIA-NIGRA IN NORMAL AGING

Based on morphological, biochemical, and molecular biologic analyses, degeneration of the dopaminergic nigrostriatal system has been reporte d to occur with normal aging. In the present study, the substantia nig ra of 36 human brains with normal aging was investigated by means of m orphometry and immunohistochemistry. The anteromedial (Am), anterointe rmediolateral (Ail), posteromedial (Pl), and posterolateral (PI) nucle i of the substantia nigra were analyzed using antibodies directed agai nst the subunits II/III of cytochrome c oxidase (COX), the complex IV of the respiratory chain. The numerical density of melanin-positive ne urons with COX defects was significantly increased in the four investi gated nuclei, namely Am, Ail, Pm, and PI. These cells did not show any histologic signs of degeneration. The numerical density of melanin-po sitive neurons without COX defects was decreased with aging. Tne data of the present study indicate that complex IV defects of neurons in th e substantia nigra might be one cause of neuronal dysfunction occurrin g during aging. Copyright (C) 1996 by Elsevier Science Inc.