Age-related changes in tyrosine hydroxylase and choline acetyltransferase in sympathetic ganglia of a rat strain with reduced sympathetic neuron numbers.

In Wistar rats, a subpopulation of sympathetic ganglionic neurons dies during ageing, but in the GH strain, these same neurons die during the period of perinatal maturation. We have compared tyrosine hydroxylase (TH) and choline acetyltransferase (ChAT) in superior cervical ganglia of GH and control rats at different ages. Ganglionic TH rose to near adult levels between postnatal weeks 1 and 2. No significant differences in TH values were seen between GH and control ganglia at any age, indicating that reduced neuron numbers are compensated for by increased cellular activity. Ganglionic ChAT rose initially in parallel with TH and then more slowly over postnatal weeks 3-4, reaching adult levels that were about 20% lower in GH than in normal ganglia. During ageing, TH remained constant but ChAT continued to rise slowly in GH ganglia, whereas ChAT in normal ganglia fell by about 10%. Both the strain difference in ChAT during development and the fall in ChAT during ageing in normal animals parallel the differences in ganglion cell numbers seen under these circumstances.