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Hypoxia–sensitive glutamatergic neurons of solitary tract nucleus (NTS) innervate the retrotrapezoid nucleus (RTN) in rats
Author(s) -
Takakura Ana Carolina Thomaz,
Moreira Thiago S,
West Gavin H,
Stornetta Ruth L,
Guyenet Patrice G
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.a788-c
Subject(s) - glutamatergic , biotinylated dextran amine , excitatory postsynaptic potential , neuroscience , hypoxia (environmental) , chemoreceptor , chemistry , solitary tract , efferent , glutamate receptor , biology , medicine , endocrinology , brainstem , nucleus , inhibitory postsynaptic potential , biochemistry , receptor , afferent , organic chemistry , oxygen
Central chemoreceptor neurons reside within the RTN. In this study, we tested whether RTN receives excitatory inputs from hypoxia‐sensitive neurons located in commissuralis NTS (commNTS). After iontophoretic injection of the anterograde tracer biotinylated dextran amine (BDA) in commNTS, most (53%) BDA‐labeled terminals in the RTN were immunoreactive for vesicular glutamate transporter‐2 (VGLUT2) but very few (5%) were immunoreactive for glutamic acid decarboxylase (GAD67). Awake rats were exposed to hypoxia (n=6) or normoxia (control) (n=5) one week after iontophoretic injection of the retrograde tracer cholera toxin B (CTB) into the RTN. Hypoxia‐activated neurons were identified by the presence of Fos‐immunoreactive (Fos‐ir) nuclei. Fos‐ir commNTS neurons retrogradely labeled with CTB were detected only in hypoxia‐treated rats. In commNTS, 51% of Fos‐ir neurons with projections to RTN (CTB‐ immunoreactive) were glutamatergic and 2% were GABAergic. In conclusion, RTN chemoreceptors may receive an excitatory glutamatergic input from peripheral chemoreceptors via a single relay in commNTS. Supported by: HL 74011 (PGG); Capes‐BEX 3495/04‐3 (TSM).