Prolonged expression of Fos-related antigens, Jun B and TrkB in dopamine-denervated striatal neurons.

Previous studies have demonstrated that striatal dopamine-denervation leads to a long-term increase in Fos-related antigen(s) (FRA's) in striatal neurons. Because Fos-family proteins bind to DNA by dimerizing to Jun-family proteins we investigated the expression of Jun B protein 2 weeks and 1 month after striatal dopamine-denervation, produced by medial forebrain bundle transection. We also investigated the effects of this lesion on TrkB-immunoreactivity in the striatum. FRA's (as previously reported) and Jun B were expressed in striatal neurons following dopamine-denervation, and in addition, there was an increase in expression of TrkB in the striatum on the dopamine-denervated side. These results show that striatal dopamine depletion leads to a long-term up-regulation of FRA's and Jun B in the striatum, and this may be related to other biochemical changes previously reported to occur in striatal neurons (e.g.: D2-dopamine receptor up-regulation) after dopamine depletion. In addition, FRA and Jun B expression may induce increased production of TrkB after dopamine-denervation.