Roles of zinc and copper in the nervous system.

Zinc deficiency in chicks and guinea pigs results in unique neurological signs, including abnormal stance and locomotion. Guinea pigs develop hypersensitivity to touch and show evidence of pain in movement. Both species exhibit decreased sciatic nerve conduction velocity. Clinical signs correlate with the peripheral neuropathy and are readily reversed by zinc therapy. Copper deficiency in second generation rats produces low dopamine levels in the corpus striatum and results in clinical signs analogous to those of Parkinson's disease. The dopamine concentration is not readily reversed by copper therapy; it correlates with striatal copper concentration, but not with liver concentration, an index of copper status. The neuropathology occurs in only part of the copper deficient population and is dam and litter related, suggesting a genetic component in addition to copper deficiency.