Nigral dopaminergic cell loss in vitamin E deficient rats.

alpha-Tocopherol concentrations in brain were reduced to 3% of control levels in rats fed a vitamin E deficient diet for 52 weeks. Vitamin E deficiency resulted in a 19-33% loss of tyrosine hydroxylase (TH) immunopositive neurones in the substantia nigra, but not in the adjacent ventral tegmental area, compared with controls. Vitamin E deficiency, however, did not reduce striatal dopamine concentrations or turnover. When antioxidant defence mechanisms are defective, as in chronic vitamin E deficiency, the nigrostriatal pathway may be affected by oxidative damage and this may have implications for Parkinson's disease.