Fos expression in the NTS in response to peripheral chemoreflex activation in awake rats

Josiane de Campos Cruz, Leni G.H. Bonagamba, Javier E. Stern, Benedito H. Machado

Research output: Contribution to journalArticlepeer-review

18 Scopus citations


Chemoreflex afferent fibers terminate in the nucleus tractus solitarii (NTS), but the specific location of the NTS neurons excited by peripheral chemoreflex activation remains to be characterized. Here, the topographic distribution of chemoreflex sensitive cells at the commissural NTS was evaluated. To reach this goal, Fos-immunoreactive neurons (Fos-ir) were accounted in rostro-caudal levels of the intermediate and caudal commissural NTS, after intermittent chemoreflex activation with intravenous injection of potassium cyanide [KCN (80 μg/kg) or saline (0.9%, vehicle), one injection every 3 min during 30 min]. In response to intermittent intravenous injections of KCN, a significant increase in the number of Fos-ir neurons was observed specifically in the lateral intermediate commissural NTS [LINTS (82 ± 9 vs. 174 ± 16, cell number mean per section)] and lateral caudal commissural NTS [LCNTS (71 ± 9 vs. 199 ± 18, cell number mean per section)]. To evaluate the influence of baroreceptor-mediated inputs following the increase in blood pressure during intermittent chemoreflex activation, we performed an intermittent activation of the arterial baroreflex by intravenous injection of phenylephrine [1.5 μg/kg iv (one injection every 3 min during 30 min)]. This procedure induced no change in Fos-ir in LINTS (64 ± 6 vs. 62 ± 12, cell number mean per section) or LCNTS (56 ± 15 vs. 77 ± 12, cell number mean per section). These data support the involvement of the commissural NTS in the processing of peripheral chemoreflex, and provide a detailed characterization of the topographical distribution of activated neurons within this brain region.

Original languageEnglish (US)
Pages (from-to)27-34
Number of pages8
JournalAutonomic Neuroscience: Basic and Clinical
Issue number1-2
StatePublished - Jan 15 2010
Externally publishedYes


  • Baroreflex
  • Cardiovascular regulation
  • Chemoreflex
  • Fos protein
  • Nucleus tractus solitarii

ASJC Scopus subject areas

  • Endocrine and Autonomic Systems
  • Clinical Neurology
  • Cellular and Molecular Neuroscience


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