Manganese and Huntington Disease

Abstract

Huntington's disease (HD) is a devastating neurodegenerative disease presenting with impaired movement, psychological and behavioral disturbances, and cognitive decline. The most pronounced symptoms are motor impairments caused by degeneration of the medium spiny neurons of the caudate and putamen. Heavy metals are closely linked with both function and dysfunction in these basal ganglia nuclei, and are, therefore, likely candidates to be the environmental modifiers for age of onset in HD. HD patient cortices and mouse in vitro and in vivo models of HD have shown decreases in accumulation of manganese (Mn2+). Manganese is a necessary cofactor for several enzymes vital to proper cellular functioning, including arginase, manganese superoxide dismutase, glutamine synthetase, and pyruvate carboxylase. Additionally, manganese has also been shown to alter cellular signaling, particularly in the IGF–AKT and ATM–p53 pathways. Manganese deficiency can result in many dysfunctional manifestations similar to Huntington's disease, including urea cycle dysfunction, altered glutamate regulation, increased oxidative stress, and metabolic disturbances, in which these enzymatic functions are crucial. In this chapter, we elaborate on the potential influence of manganese and other metals in Huntington's disease; we also investigate the potential role of manganese-dependent enzymes in HD pathophysiology.