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C1 neurons excite locus coeruleus and A5 noradrenergic neurons along with the sympathetic outflow
Author(s) -
Abbott Stephen B,
Kanbar Roy,
Coates Melissa B,
Stornetta Ruth J,
Guyenet Patrice G
Publication year - 2011
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.25.1_supplement.1075.13
Subject(s) - photostimulation , locus coeruleus , neuroscience , optogenetics , excitatory postsynaptic potential , retrograde tracing , catecholaminergic , biology , catecholaminergic cell groups , chemistry , nucleus , inhibitory postsynaptic potential , dopamine
C1 neurons in the ventrolateral medulla mediate the response of peripheral sympathetic afferents and the hypothalamic‐pituitary‐adrenal axis to somatic and visceral stimuli. Additionally, C1 neurons innervate noradrenergic neurons in the locus coeruleus (LC) and A5 region. The C1‐LC projection is believed to act through glutamatergic/catecholaminergic transmitter release, whereas the C1‐A5 projection has not been characterised. Here, we examine the C1‐LC and C1‐A5 connection with an optogenetic approach. Using a viral vector that expresses channelrhodopsin2 (ChR2) under the control of the artificial promoter PRSx8 we restricted ChR2 expression to C1 neurons (65%), retrotrapezoid nucleus (RTN) chemoreceptors (22%) and cholinergic motor neurons (N=17). In these rats, photostimulation of the ChR2‐expressing neurons activated around two thirds of LC and A5 noradrenergic neurons and greatly increased renal sympathetic nerve activity (SNA). After lesioning both RTN and rostral C1 neurons with a saporin‐based toxin, we obtained rats in which 83% of ChR2‐expressing neurons were C1 and almost the entire balance were motor neurons (N=7). In these rats photostimulation activated LC and A5 neurons exactly as in control rats but produced no SNA increase. In conclusion, the C1‐LC connection is excitatory, largely distinct subsets of C1 neurons regulate LC vs. SNA and the C1 cells also excite the A5 neurons.