Tyrosine hydroxylase activity in Venezuelan equine encephalomyelitis virus infection.

In rats inoculated with the Venezuelan equine encephalomyelitis (VEE) virus, a significant decrease was found in the tyrosine hydroxylase activity of neostriatum, midbrain, and hypothalamus during the acute phase of the infection. In animals that survived the acute infection, we observed no changes in the enzymatic activity in the same regions studied. Our findings suggest a vulnerability of the dopaminergic and noradrenergic pathways to the infection produced by VEE virus.