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Systemic hypertension and hypotension produce a similar distribution of Fos expressing neurons in nucleus tractus solitarii (NTS).
Author(s) -
Austgen James R,
King L T,
Fong A Y,
Heesch C M,
Mueller P J,
Foley C M,
Potts J T,
Hasser E M
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a361-c
Subject(s) - baroreceptor , rostral ventrolateral medulla , area postrema , solitary nucleus , medulla , solitary tract , medicine , c fos , colocalization , baroreflex , medulla oblongata , endocrinology , gabaergic , anesthesia , blood pressure , chemistry , neuroscience , biology , heart rate , central nervous system , receptor , gene expression , biochemistry , gene
The NTS is a highly integrative region receiving afferent projections from the arterial baroreceptors. Neurons in the NTS are activated by both increasing and decreasing baroreceptor input by changing arterial pressure (AP). We have begun testing the hypothesis that different populations of NTS neurons are activated by hypertension vs. hypotension. The retrograde tracer Fluoro‐Gold (FG, 2%, 15–30 nL) was microinjected unilaterally into the caudal ventrolateral medulla (CVLM) of male rats to label NTS output neurons, and arterial and venous catheters were implanted. Five days later, conscious rats were subjected to sustained (90 min) increases (phenylephrine, PE, +44 ± 4.4 mmHg) or decreases (diazoxide, DZ, −52±6.5 mmHg) in AP. Rats were then transcardially perfused and 30 μm medullary sections throughout the NTS were stained for Fos, to evaluate neuronal activation, and GAD67 to identify GABA synthesizing neurons. The total number of Fos expressing neurons was similar for both PE (415 ± 16) and DZ (502 ± 21) treated rats throughout the rostral‐caudal extent of the NTS, with the greatest expression at the level of the area postrema (PE, 45%; DZ, 52%). PE and DZ also resulted in colocalization of Fos+GAD67 and Fos+FG positive cells in NTS. These findings suggest that despite differences in baroreceptor input the rostral‐caudal pattern of Fos expression in the NTS was similar. In addition, both GABAergic and CVLM‐projecting neurons are activated in response to hypertension and hypotension. Support by HL54669 (EMH) and HL059167 (JTP)