Medullary norepinephrine neurons modulate local oxygen concentrations in the bed nucleus of the stria terminalis.
Neurovascular coupling is understood to be the underlying mechanism of functional hyperemia, but the actions of the neurotransmitters involved are not well characterized. Here we investigate the local role of the neurotransmitter norepinephrine in the ventral bed nucleus of the stria terminalis (vBNST) of the anesthetized rat by measuring O₂, which is delivered during functional hyperemia. Extracellular changes in norepinephrine and O₂ were simultaneously monitored using fast-scan cyclic voltammetry. Introduction of norepinephrine by electrical stimulation of the ventral noradrenergic bundle or by iontophoretic ejection induced an initial increase in O₂ levels followed by a brief dip below baseline. Supporting the role of a hyperemic response, the O₂ increases were absent in a brain slice containing the vBNST. Administration of selective pharmacological agents demonstrated that both phases of this response involve β-adrenoceptor activation, where the delayed decrease in O₂ is sensitive to both α- and β-receptor subtypes. Selective lesioning of the locus coeruleus with the neurotoxin DSP-4 confirmed that these responses are caused by the noradrenergic cells originating in the nucleus of the solitary tract and A1 cell groups. Overall, these results support that non-coerulean norepinephrine release can mediate activity-induced O₂ influx in a deep brain region.
Department of Chemistry and Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Elizabeth S
ES
Bucher
Department of Chemistry and Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Megan E
ME
Fox
Department of Chemistry and Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Laura
L
Kim
Department of Chemistry and Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Douglas C
DC
Kirkpatrick
Department of Chemistry and Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Nathan T
NT
Rodeberg
Department of Chemistry and Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
Anna M
AM
Belle
Department of Chemistry and Neuroscience Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.
R Mark
RM
Wightman
D000818:Animals; D004558:Electric Stimulation; D006940:Hyperemia / Q000378:metabolism*; D007150:Immunohistochemistry; D007478:Iontophoresis; D008297:Male; D008526:Medulla Oblongata / Q000166:cytology / Q000378:metabolism; D009474:Neurons / Q000378:metabolism*; D009638:Norepinephrine / Q000378:metabolism*; D009924:Organ Culture Techniques; D010100:Oxygen / Q000097:blood*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012686:Septal Nuclei / Q000378:metabolism*
D010100:Oxygen; D009638:Norepinephrine