Influence of Venezuelan equine encephalomyelitis virus on catecholamine metabolism in mouse CNS: early changes in turnover rates and content.

The influence of two strains of Venezuelan equine encephalomyelitis virus on catecholamine metabolism in the central nervous system (CNS) of the mouse was studied by the intracranial inoculation of NMRI-IVIC mice, 24 days old. Doses of 300 LD50 of the moderately virulent Pixuna strain and 10(4) LD50 of the nonvirulent TC-83 strain were used. The animals were sacrificed 4, 7, 12, and 18 days after the inoculation, and the CNS contents of dopamine, norepinephrine, and adrenaline were determined by a radioenzymatic method. The turnover of these compounds was studied with the aid of the enzymatic inhibitors pargyline and alpha-methyl tyrosine. With the Pixuna strain a decrease in the level and turnover of catecholamines was observed in all eight brain areas studied: cerebellum, pons-medulla, hypothalamus, mesencephalon, striatum, olfactory bulb-tuberculum, hippocampus, and cerebral cortex. In some regions the levels returned to normal in 12-18 days, but in the striatum, mesencephalon, hypothalamus, and olfactory bulb-tuberculum, recovery was slower and required at least 18 days after inoculation. The levels of catecholamines in the brain of mice inoculated with the nonvirulent TC-83 strain were not modified, but there was a decrease in the turnover.