ABSTRACT

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Zinc (Zn) is an essential trace metal in humans and animals, especially during pregnancy. Zn is absorbed from the small intestine and its absorption is inhibited by fiber, phytates, calcium (Ca), and copper (Cu) and is enhanced by amino acids, peptides, and chelating agents. Elimination of Zn occurs primarily through pancreatic and intestinal secretion. Zn is loosely bound to albumin and other proteins in the blood and 99% of the metal in the body is inside cells. Zn deficiency results in defects of the central nervous system (CNS) and in peripheral neuropathy. 1 Enzymatic Zn, which is firmly incorporated into the structure of Zn-metalloenzyrnes, plays no unique role in neural tissue, whereas ionic Zn (Zn2•) is the fraction of tissue Zn that appears to be associated with secretory-signaling functions of certain neurons. Zn plays an important role in synaptic function in the brain, as it is present in synaptic vesicles, is released with neuronal activity, and provides modulation of different neurotransmitters. The clinical symptoms of Zn deficiency other than those in the CNS are described elsewhere.2 We focus herein on the roles of Zn in CNS function and describe CNS disorders related to Zn deficiency.