Phenotypic identification of rat rostroventrolateral medullary presympathetic vasomotor neurons inhibited by exogenous cholecystokinin

Systemic administration of the gastrointestinal hormone cholecystokinin (CCK) selectively inhibits splanchnic sympathetic vasomotor discharge and differentially affects presympathetic vasomotor neurons of the rostroventrolateral medulla (RVLM). Stimulation of the sympathoexcitatory region of the per...

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Bibliographic Details
Published in:Journal of comparative neurology (1911) 2003-10, Vol.465 (4), p.467-479
Main Authors: Sartor, Daniela M., Verberne, Anthony J.M.
Format: Article
Language:English
Subjects:
Animals
Axons - drug effects
Axons - physiology
Biotin - analogs & derivatives
Blood Pressure - drug effects
Blood Pressure - physiology
Cell Size - physiology
Cholecystokinin - metabolism
Cholecystokinin - pharmacology
Efferent Pathways - cytology
Efferent Pathways - drug effects
Efferent Pathways - metabolism
Epinephrine - metabolism
gastrointestinal blood flow
juxtacellular labelling
Male
Medulla Oblongata - cytology
Medulla Oblongata - drug effects
Medulla Oblongata - metabolism
Mesenteric Arteries - innervation
Mesenteric Arteries - physiology
Neural Conduction - drug effects
Neural Conduction - physiology
Neural Inhibition - drug effects
Neural Inhibition - physiology
Neurons - cytology
Neurons - drug effects
Neurons - metabolism
Periaqueductal Gray - cytology
Periaqueductal Gray - drug effects
Periaqueductal Gray - physiology
periaqueductal grey
Phenotype
Phenylethanolamine N-Methyltransferase - metabolism
phenylethanolamine-N-methyl-transferase
Rats
Rats, Sprague-Dawley
Regional Blood Flow - drug effects
Regional Blood Flow - physiology
rostral ventrolateral medulla
Spinal Cord - drug effects
Spinal Cord - physiology
Sympathetic Nervous System - cytology
Sympathetic Nervous System - drug effects
Sympathetic Nervous System - metabolism
Vasomotor System - drug effects
Vasomotor System - physiology
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Summary:Systemic administration of the gastrointestinal hormone cholecystokinin (CCK) selectively inhibits splanchnic sympathetic vasomotor discharge and differentially affects presympathetic vasomotor neurons of the rostroventrolateral medulla (RVLM). Stimulation of the sympathoexcitatory region of the periaqueductal grey (PAG) produces profound mesenteric vasoconstriction. In this study, our aim was to identify phenotypically different populations of RVLM presympathetic vasomotor neurons using juxtacellular neuronal labelling and immunohistochemical detection of the adrenergic neuronal marker phenylethanolamine‐N‐methyl transferase (PNMT) and to determine whether the PAG provides functional excitatory input to these neurons. Fifty‐eight percent (36/62) of RVLM presympathetic neurons were inhibited by systemic administration of CCK. These cells had conduction velocities (3.6 ± 0.2 m/sec) in the non‐C‐fiber range consistent with neurons possessing lightly myelinated spinal axons. Of these, 79% (22/28) were excited by PAG stimulation, and 59% (10/17) were not immunoreactive for PNMT. Conversely, 42% (26/62) of RVLM presympathetic neurons were either unaffected or activated by CCK administration and had slower conduction velocities (1.4 ± 0.3 m/sec) than cells inhibited by CCK. Fifty percent (11/22) of these cells were driven by PAG stimulation, and most (11/14 or 79%) were PNMT‐positive. These results suggest that cardiovascular responses elicited by PAG stimulation occur via activation of non‐C1 and C1 RVLM presympathetic neurons. RVLM neurons inhibited by CCK were more likely to be driven by PAG stimulation and may be a subset of neurons responsible for driving gastrointestinal sympathetic vasomotor tone. CCK‐induced inhibition of a subpopulation of RVLM presympathetic neurons may be implicated in postprandial hyperemia and postprandial hypotension. J. Comp. Neurol. 465:467–479, 2003. © 2003 Wiley‐Liss, Inc.
ISSN:0021-9967
1096-9861
DOI:10.1002/cne.10840