CHRONIC ARTHRITIS INCREASES TYROSINE-HYDROXYLASE MESSENGER-RNA LEVELSIN THE PONTINE NORADRENERGIC CELL GROUPS

In situ hybridization was used to examine the change of tyrosine hydro xylase(TH) mRNA levels in the pontine noradrenergic cell groups of chr onic monoarthritic rats induced by adjuvant inoculation. The number of TH mRNA-expressing neurons and grains per labeled neuron in the A5, A 6 and A7 cell groups on the ipsilateral and contralateral sides signif icantly increased 2 weeks after adjuvant inoculation into the left tib io-tarsal joint, compared to controls. These results suggest that nora drenalin in the pontine region may play a role in modulating chronic n ociceptive stimuli.