TY - JOUR
T1 - Fos expression in the NTS in response to peripheral chemoreflex activation in awake rats
AU - Cruz, Josiane de Campos
AU - Bonagamba, Leni G.H.
AU - Stern, Javier E.
AU - Machado, Benedito H.
N1 - Funding Information:
In Brazil these studies were funded by FAPESP ( 2004/03285-7 ) and CNPQ ( 522150/95-0 ). J.C.C. was supported by a CAPES fellowship. In USA, funding was provided by NIH HL68725 (JES).
PY - 2010/1/15
Y1 - 2010/1/15
N2 - 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.
AB - 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.
KW - Baroreflex
KW - Cardiovascular regulation
KW - Chemoreflex
KW - Fos protein
KW - Nucleus tractus solitarii
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U2 - 10.1016/j.autneu.2009.08.016
DO - 10.1016/j.autneu.2009.08.016
M3 - Article
C2 - 19783484
AN - SCOPUS:72049087733
SN - 1566-0702
VL - 152
SP - 27
EP - 34
JO - Autonomic Neuroscience: Basic and Clinical
JF - Autonomic Neuroscience: Basic and Clinical
IS - 1-2
ER -