Introduction
The non-infectious neurodegenerative disorders, Alzheimer's disease, and amyotrophic lateral sclerosis are heterogeneous with respect to etiology, neuropathology and clinical presentation. Yet, these disorders share a number of features in common to suggest some common pathogenic events. Each disorder is age related and is characterized by progressive and symmetric degeneration of discrete populations of neurons. Each disorder is associated with biochemical markers of oxidative attack, and each is associated with deposition of a CuZn metalloprotein in affected tissue.
Molecular genetic analysis has linked autosomal dominant forms of AD, PD, and amyotrophic lateral sclerosis, respectively, to mutations in ß-amyloid precursor protein, α-synuclein, and superoxide dismutase 1. Each of these proteins or its proteolytic products may aggregate in affected tissue during the course of disease.
In this chapter we summarize current knowledge of CNS Cu and Zn metabolism in normal physiology. Then, focusing on AD and ALS, we review evidence for pathophysiologic Cu and Zn metabolism and evidence linking Cu and Zn to the physiologic and toxic activities of ß-amyloid protein and superoxide dismutase 1.
Protein interactions in brain copper and zinc metabolism
At the active site of many enzymes, Cu participates in one-electron transfer reactions. Zn, which is electrochemically inert, maintains structural stability of many proteins. In addition to these essential and ubiquitous roles for Cu and Zn, brain-specific functions exist for these metals.