Abstract
The central baroreceptive neurons in the medulla oblongata express specific basic-leucine zipper (bZIP) transcription factors after baroreceptor stimulation. Here we studied the effects of baroreceptor stimulation on MafG induction in the rat medulla oblongata. MafG is a member of the small Maf protein family that functions as dimeric partners for various bZIP transcription factors by forming transcription-regulating complexes. To determine whether gene expression of MafG is induced in the medulla oblongata after stimulation of arterial baroreceptors by phenylephrine (PE), we examined the expression of the mRNA by the RT-PCR method and that of gene product MafG by immunohistochemistry. The number of MafG transcripts increased significantly in the medulla oblongata after the baroreceptor stimulation. In the PE pressor experiments, MafG-immunoreactive (IR) neurons were distributed in cardiovascular control sites: the NTS, DMX, AMB, CVLM and RVLM. The numbers of MafG-IR neurons in these nuclei were significantly greater in the PE-injected rats than in control rats. The temporal expression pattern of MafG was found to coincide with that of immediate early genes such as Fos. Our results suggest that MafG may play critical roles as an immediate early gene in the signal transduction of cardiovascular regulation mediated by baroreceptive signals in the medulla oblongata. [Jpn J Physiol 54 Suppl:S195 (2004)]
