PNMT-containing neurons of the C1 cell group express c-fos in response to changes in baroreceptor input.
The immunocytochemical detection of Fos, the protein product of the immediate-early gene c-fos, was used as a marker for activated neurons to examine whether the C1 neurons in the rat rostral ventrolateral medulla (RVLM) respond to changes in baroreceptor afferent activity. After hydralazine-induced hypotension or sinoaortic denervation, two treatments that reduce baroreceptor afferent activity, numerous Fos-positive neurons were observed in the RVLM. The number of Fos-positive neurons in the RVLM was counted in brain stem sections from hydralazine-treated rats that had been previously injected with Fluorogold into the upper thoracic spinal cord to label spinally projecting RVLM neurons as well as stained for phenylethanolamine-N-methyltransferase (PNMT) as a marker of C1 neurons. The results indicate that approximately 80% of the C1 neurons expressed Fos in response to hydralazine injection; this was true of spinally projecting C1 neurons as well as those C1 neurons that were not labeled with Fluorogold. Furthermore, in hydralazine-treated rats, the majority of Fluorogold-labeled Fos-positive neurons contained PNMT. These results suggest that C1 neurons are sensitive to baroreceptor afferent input and support a role of these neurons in cardiovascular regulation.
Sved
A F
AF
Department of Behavioral Neuroscience, University of Pittsburgh, Pennsylvania 15260.
Mancini
D L
DL
Graham
J C
JC
Schreihofer
A M
AM
Hoffman
G E
GE
D000818:Animals; D015870:Gene Expression / Q000187:drug effects; D016762:Genes, fos; D006706:Homeostasis; D006830:Hydralazine / Q000494:pharmacology; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D010625:Phenylethanolamine N-Methyltransferase / Q000032:analysis / Q000378:metabolism*; D011311:Pressoreceptors / Q000187:drug effects / Q000502:physiology*; D016760:Proto-Oncogene Proteins c-fos / Q000096:biosynthesis*; D051381:Rats; D017207:Rats, Sprague-Dawley
D016760:Proto-Oncogene Proteins c-fos; D006830:Hydralazine; D010625:Phenylethanolamine N-Methyltransferase