Catecholaminergic C3 neurons are sympathoexcitatory and involved in glucose homeostasis.
Brainstem catecholaminergic neurons play key roles in the autonomic, neuroendocrine, and behavioral responses to glucoprivation, yet the functions of the individual groups are not fully understood. Adrenergic C3 neurons project widely throughout the brain, including densely to sympathetic preganglionic neurons in the spinal cord, yet their function is completely unknown. Here we demonstrate in rats that optogenetic stimulation of C3 neurons induces sympathoexcitatory, cardiovasomotor functions. These neurons are activated by glucoprivation, but unlike the C1 cell group, not by hypotension. The cardiovascular activation induced by C3 neurons is less than that induced by optogenetic stimulation of C1 neurons; however, combined stimulation produces additive sympathoexcitatory and cardiovascular effects. The varicose axons of C3 neurons largely overlap with those of C1 neurons in the region of sympathetic preganglionic neurons in the spinal cord; however, regional differences point to effects on different sympathetic outflows. These studies definitively demonstrate the first known function of C3 neurons as unique cardiovasomotor stimulatory cells, embedded in the brainstem networks regulating cardiorespiratory activity and the response to glucoprivation.
Department of Physiology, University of Melbourne, Victoria, 3010 Australia.
Clément
C
Menuet
Department of Physiology, University of Melbourne, Victoria, 3010 Australia.
Charles P
CP
Sevigny
Department of Physiology, University of Melbourne, Victoria, 3010 Australia.
Angela A
AA
Connelly
Department of Physiology, University of Melbourne, Victoria, 3010 Australia.
Jaspreet K
JK
Bassi
Department of Physiology, University of Melbourne, Victoria, 3010 Australia.
Nikola
http://orcid.org/0000-0003-0468-7914
N
Jancovski
Department of Physiology, University of Melbourne, Victoria, 3010 Australia.
David A
DA
Williams
Department of Anatomy and Neurosciences, University of Melbourne, Victoria, 3010 Australia.
Colin R
CR
Anderson
Cardiovascular Medicine, School of Medicine, Flinders University, Bedford Park, South Australia, 5042 Australia, and Human Physiology, School of Medicine, Flinders University, Bedford Park, South Australia, 5042 Australia.
Ida J
IJ
Llewellyn-Smith
Department of Physiology, University of Melbourne, Victoria, 3010 Australia.
Angelina Y
AY
Fong
Department of Physiology, University of Melbourne, Victoria, 3010 Australia, a.allen@unimelb.edu.au.
Andrew M
http://orcid.org/0000-0002-2183-5360
AM
Allen
D000200:Action Potentials; D000320:Adrenergic Fibers / Q000378:metabolism / Q000502:physiology*; D000818:Animals; D001933:Brain Stem / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D005947:Glucose / Q000378:metabolism*; D006321:Heart / Q000294:innervation* / Q000502:physiology; D006706:Homeostasis; D008297:Male; D051381:Rats; D017207:Rats, Sprague-Dawley; D013564:Sympathetic Nervous System / Q000166:cytology / Q000378:metabolism / Q000502:physiology*
D005947:Glucose
channelrhodopsin; glucoprivation; rostral ventrolateral medulla; sympathetic nervous system