Regional tyrosine hydroxylase and choline acetyltransferase concentrations in the brains of lymphocytic choriomeningitis-infected mice.

The neurotransmitter biosynthesis enzymes tyrosine hydroxylase and choline acetyltransferase were investigated in selected brain areas of Nya : NYLAR mice infected with lymphocytic choriomeningitis (LCM) virus. Statistically significant alterations in the concentrations of both enzymes occurred in the olfactory, caudate, and neocortical regions at 5 days postinfection. No such alterations occurred in mice given cytoxan (150 mg/kg) 3 days postinfection and examined 5 days postinfection. At 10 days postinfection, however, the cytoxan-treated animals had significantly altered enzyme concentrations in the olfactory region, though not in the caudate or neocortex. This alteration appeared to be transitory, since it was not found in cytoxan-treated animals 60 days postinfection. A possible explanation is that virus production or interference in a brain region cycles over a period of hours or days. Still undetermined is whether these neurochemical changes are a primary effect of the virus or a secondary effect due to the immune response. It is noteworthy that cytoxan caused a marked increase in the enzyme activities studied in most of the brain areas.