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Characterization of caudal ventrolateral medulla‐projection neurons originating from the nucleus of the solitary tract
Author(s) -
Kline David D.,
Austgen James R.,
Friskey Sarah A.,
Hasser Eileen M.
Publication year - 2007
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.21.5.a464-a
Subject(s) - medulla , depolarization , excitatory postsynaptic potential , solitary nucleus , solitary tract , rostral ventrolateral medulla , medulla oblongata , neuroscience , chemistry , afterhyperpolarization , anatomy , nucleus , biophysics , inhibitory postsynaptic potential , biology , central nervous system
The central component of the baroreflex consists of projections from the nucleus tractus solitarius (NTS) to the caudal ventrolateral medulla (CVLM), rostral VLM and intermediolateral cell column. Within the NTS, baroafferent activity is integrated and sent to the CVLM. We examined the location and properties of CVLM‐projecting NTS neurons. Fluoro‐Gold (FG) or latex beads were injected in the CVLM for retrograde NTS labeling. FG was observed in the ipsilateral dorsomedial, medial, and ventrolateral NTS. Similar observations were made using latex beads, which were utilized in brain slice recordings. CVLM‐projection cells exhibited large spontaneous excitatory postsynaptic currents (EPSCs, 27.9 ± 2.7 pA, 2.6 ± 0.6 Hz, n=6). Step depolarization from −80 to 80 mV (50 ms steps) elicited outward transient and delayed rectifier potassium currents activating at −50 mV (n=4). Stimulation of the solitary tract evoked EPSCs (151.3 ± 73.9 pA, n=5), confirming output neurons were connected to the NTS network. In current clamp, resting membrane potential was −52.4 ± 3.2 mV (n=5). Action potentials had a threshold of −37.5 ± 2.6 mV, amplitude of 64.4± 7.6 mV and afterhyperpolarization of −7.2 ± 1.4 mV (n=4). Results demonstrate NTS embedded CVLM‐projection neurons studied in the medullary slice provide a means to determine network mechanisms mediating the baroreflex. Support: UMC (DDK) and HL55306, HL55469 (EMH).