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

Author(s)

Cruz, Josiane de Campos ^[1] ; Bonagamba, Leni G. H. ^[1] ; Stern, Javier E. ^[2] ; Machado, Benedito H. ^[1]

Affiliation

^[1] Univ Sao Paulo, Sch Med Ribeirao Preto, Dept Physiol, BR-14049900 Ribeirao Preto, SP - Brazil

^[2] Med Coll Georgia, Dept Physiol, Sch Med, Augusta, GA 30912 - USA

• Document type: Journal article
• Source: AUTONOMIC NEUROSCIENCE-BASIC & CLINICAL; v. 152, n. 1-2, p. 27-34, JAN 15 2010.
• Web of Science Citations: 15

Abstract

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 mu g/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 {[}(LI)NTS (82 +/- 9 vs. 174 +/- 16, cell number mean per section)] and lateral caudal commissural NTS {[}(LI)NTS (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 mu g/kg iv (one injection every 3 min during 30 min)]. This procedure induced no change in Fos-ir in (LI)NTS (64 +/- 6 vs. 62 +/- 12, cell number mean per section) or (LC)NTS (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. (C) 2009 Elsevier B.V. All rights reserved. (AU)

• FAPESP's process: 04/03285-7 - Central mechanisms involved in the sympathoexcitation in response to hypoxia
• Grantee: Benedito Honorio Machado
• Support Opportunities: Research Projects - Thematic Grants