title: Changes in the regional and compartmental distribution of FosB- and JunB-like immunoreactivity induced in the dopamine-denervated rat striatum by acute or chronic L-dopa treatment.
abstract: This study was carried out in order to examine the effects of acute or chronic L-DOPA treatment on striatally expressed FosB- and JunB-like proteins in a rat model of Parkinson's disease. Rats with a unilateral, near-total 6-hydroxydopamine lesion of the ascending mesostriatal projection received either an acute challenge or a one-week treatment with 10 mg/kg/day methyl L-DOPA (combined with 15 mg/mg benserazide), and were killed at either 3 h or two days post-injection. Both acute and chronic L-DOPA treatment caused a pronounced, persistent increase in the number of FosB-like immunoreactive cells in the dopamine-denervated striata (five- and seven-fold increase, respectively, above the levels found in lesioned but non-drug-treated controls), but the two treatment groups differed markedly with respect to both the average amount of staining per cell, which was two-fold larger in the chronic L-DOPA cases, and the anatomical distribution of the labeled cells. After an acute injection of L-DOPA, FosB-positive cells were distributed rather uniformly across all striatal subregions, whereas chronic L-DOPA treatment induced discrete clusters of strongly FosB-like immunoreactive cells within medial and central striatal subregions, as well as in a large, yet sharply defined portion of the lateral caudate-putamen. Strongly labeled cell clusters that appeared in the medial and central caudate-putamen were preferentially located within calbindin-poor, mu-opioid receptor-rich striosomes, whereas the lateral area displaying FosB activation encompassed both striosomal and matrix domains. In both the medial and the lateral striatum a near-total overlap was found between strongly FosB-like immunoreactive cell groups and areas showing pronounced dynorphin expression. NADPH-diaphorase-positive striatal interneurons did not express FosB-like immunoreactivity after a 6-hydroxydopamine lesion alone, a negligible proportion of them did after an acute L-DOPA challenge, but about 8% of these interneurons were FosB positive following chronic L-DOPA treatment. Like FosB, JunB was induced in the DA-denervated striatum by both acute and chronic L-DOPA treatment, and exhibited similar distribution patterns. However, JunB did not exhibit prolonged expression kinetics, and was somewhat down-regulated in the chronically compared with the acutely L-DOPA-treated rats. The present results show that L-DOPA administration produces a long-lasting increase in the levels of FosB-, but not JunB-like immunoreactivity in the dopamine-denervated striatum. More importantly, these data show that striatal induction of FosB- and JunB-like proteins by chronic L-DOPA treatment exhibits both regional and compartmental specificity.
authors.affiliation: Department of Neurobiology, Institute of Physiological Sciences, University of Lund, Wallenberg Neuroscience Center, Sweden.
authors.forename: M A
authors.initials: MA
authors.lastname: Cenci
authors.forename: A
authors.initials: A
authors.lastname: Tranberg
authors.forename: M
authors.initials: M
authors.lastname: Andersson
authors.forename: A
authors.initials: A
authors.lastname: Hilbertson
mesh_terms: D000818:Animals; D003342:Corpus Striatum / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D003714:Denervation; D004298:Dopamine / Q000502:physiology*; D004334:Drug Administration Schedule; D005106:Exploratory Behavior / Q000187:drug effects; D005260:Female; D007839:Functional Laterality; D007980:Levodopa / Q000008:administration & dosage / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects; D016627:Oxidopamine; D020734:Parkinsonian Disorders / Q000139:chemically induced / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000032:analysis / Q000096:biosynthesis*; D016755:Proto-Oncogene Proteins c-jun / Q000032:analysis / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D007980:Levodopa; D016627:Oxidopamine; D004298:Dopamine