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Medullary “raphé chemosensory amplifier” (RCA) interneurons are mediated by serotonin/substance P and GABA‐synthesizing neurons in situ
Author(s) -
Iceman Kimberly Erin,
Harris Michael Bruce
Publication year - 2013
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.27.1_supplement.1137.22
Subject(s) - serotonergic , raphe , serotonin , 5 ht receptor , substance p , neuroscience , chemistry , neurotransmitter , raphe nuclei , endocrinology , medicine , biology , receptor , neuropeptide , central nervous system
Serotonin/substance P (5‐HT/SP) and GABA‐synthesizing neurons in the rat medullary raphé are stimulated and inhibited, respectively, by elevated CO 2 (hypercapnia) in vitro and in situ . The raphé nuclei neurons are heterogeneous with respect to neurotransmitter phenotype and responses to hypercapnia. We have identified a type of chemosensitive raphé neuron that is stimulated by hypercapnia but is not serotonergic. We test the hypothesis that these CO 2 ‐stimulated “raphé chemosensory amplifier” (RCA) interneurons receive critical network input from 5‐HT/SP and GABA neurons, mediated by 5HT 2A , NK‐1, and GABA A receptors. We assess chemosensitivity of individual raphé RCA interneurons before and after bath pharmacological antagonism of these receptors in the unanesthetized juvenile rat in situ perfused decerebrate brainstem preparation. Coupled with juxtacellular labeling and subsequent immunohistochemistry, we demonstrate RCA interneurons are non‐serotonergic, express NK‐1 receptors, and are dependent on 5HT 2A and GABA A receptors for tonic drive and chemosensitivity, suggesting a raphé network sensitive and responsive to hypercapnia. Supported by NIH 2U54NS041069–06A1 and P20GM103395.