Parafascicular thalamic nucleus deafferentation reduces c-fos expression induced by dopamine D-1 receptor stimulation in rat striatum.
We investigated the role played by the parafascicular thalamostriatal pathway, one of the major excitatory inputs to the striatum, in the D-1 receptor induction of c-fos messenger RNA expression in the rat striatum. The full D-1 receptor agonist, SKF-82958 (0.05, 0.1, 0.5 and 1 mg/kg, s.c., 30 min), dose-dependently induced c-fos messenger RNA in naive rat striatum as determined by northern blot analysis. One day following electrolytic lesion of the parafascicular thalamostriatal nucleus, striatal c-fos signal by itself was not altered but the stimulated expression of c-fos was strongly decreased. Sections of sham-operated and acute-lesioned dorsal striata of vehicle- or SKF-82958-treated rats were processed for in situ hybridization histochemistry at the single-cell level with an RNA probe for c-fos. The basal expression of striatal c-fos was poorly detectable in sham and lesioned groups. Sections of dorsal striata from sham-operated rats treated with SKF-82958 showed two types of labeled neurons for c-fos: the lightly and the very densely labeled neurons which are few in number. Thalamic lesion strongly reduced SKF-82958 stimulated expression of c-fos RNA in both types of labeled cells. The frequency distribution of c-fos labeling per neuron in dorsal striata of lesioned rats treated with SKF-82958 was shifted to the left, and its median was lower than in the sham-operated striata treated with the D-1 receptor agonist. The results provide evidence that the excitatory projections from the parafascicular nucleus of the thalamus, thought to operate primarily through the N-methyl-D-aspartate receptors, exert a facilitatory control over D-1 receptor-induced c-fos gene expression specifically in the dorsal striatum.
Istituto di Ricerche Farmacologiche, Mario Negri, Viale Eritrea 62, 20157 Milan, Italy. Visentin.Giorgi@libero.it
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D000344:Afferent Pathways / Q000502:physiology; D000818:Animals; D001552:Benzazepines / Q000494:pharmacology; D003342:Corpus Striatum / Q000166:cytology / Q000378:metabolism*; D003714:Denervation; D018491:Dopamine Agonists / Q000494:pharmacology; D020646:Intralaminar Thalamic Nuclei / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000502:physiology*
D001552:Benzazepines; D018491:Dopamine Agonists; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D017447:Receptors, Dopamine D1; C071262:SK&F 82958