title: Neuronal expression of nuclear transcription factor MafG in the rat medulla oblongata after baroreceptor stimulation.
abstract: The medulla oblongata is the site of central baroreceptive neurons in mammals. These neurons express specific basic-leucine zipper transcription factors (bZIP) after baroreceptor stimulation. Previously we showed that activation of baroreceptors induced expression of nuclear transcription factors c-Fos and FosB in central baroreceptive neurons. Here we studied the effects of baroreceptor stimulation on induction of MafG, a member of small Maf protein family that functions as dimeric partners for various bZIP transcription factors by forming transcription-regulating complexes, in the rat medulla oblongata. To determine whether gene expression of MafG is induced by stimulation of arterial baroreceptors, we examined the expression of its mRNA by semi-quantitative reverse transcription-PCR method and its gene product by immunohistochemistry. We found that the number of MafG transcripts increased significantly in the medulla oblongata after baroreceptor stimulation. MafG-immunoreactive neurons were distributed in the nucleus tractus solitarii, the dorsal motor nucleus of the vagus nerve, the ambiguous nucleus and the ventrolateral medulla. The numbers of MafG-immunoreactive neurons in these nuclei were significantly greater in test rats than in saline-injected control rats. We also found approximately 20% of MafG-immunoreactive neurons coexpress FosB after baroreceptor stimulation. Our results suggest that MafG cooperates with FosB to play critical roles as an immediate early gene in the signal transduction of cardiovascular regulation mediated by baroreceptive signals in the medulla oblongata.
authors.affiliation: Department of Laboratory Sciences, Gunma University School of Health Sciences, 3-39-15 Showa-machi, Maebashi-shi 371-8514, Japan.
authors.forename: Iku
authors.initials: I
authors.lastname: Kumaki
authors.forename: Dawei
authors.initials: D
authors.lastname: Yang
authors.forename: Noriyuki
authors.initials: N
authors.lastname: Koibuchi
authors.forename: Kiyoshige
authors.initials: K
authors.lastname: Takayama
mesh_terms: D000818:Animals; D015870:Gene Expression / Q000187:drug effects*; D051259:MafG Transcription Factor / Q000096:biosynthesis* / Q000235:genetics; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology; D011311:Pressoreceptors / Q000378:metabolism*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis / Q000235:genetics; D051381:Rats; D017208:Rats, Wistar; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: C483820:Fosb protein, rat; D051259:MafG Transcription Factor; D016760:Proto-Oncogene Proteins c-fos; D010656:Phenylephrine