Adrenal epinephrine secretion is not regulated by sympathoinhibitory neurons in the caudal ventrolateral medulla

Madhusudan Natarajan, Shaun Morrison

Research output: Contribution to journalArticle

21 Citations (Scopus)

Abstract

By providing the principal inhibitory regulation of the discharge of sympathetic premotor neurons in the rostral ventrolateral medulla (RVLM), neurons in the caudal ventrolateral medulla (CVLM) play a major role in regulating the level of sympathetic nerve activity (SNA) to cardiovascular targets. To determine whether adrenal medullary secretion of epinephrine (EPI) is also regulated by sympathoinhibitory inputs from the CVLM to the RVLM, we compared levels of plasma EPI obtained after disinhibition of RVLM neurons with levels obtained after inhibition of CVLM neurons, both of which result in sustained elevations in arterial blood pressure (AP), SNA, and heart rate (HR). Plasma norepinephrine (NE) concentrations were significantly elevated following bilateral microinjection either of bicuculline (BIC) into the RVLM or of muscimol into the CVLM of urethane/chloralose-anesthetized, artificially-ventilated rats. In sharp contrast, although plasma EPI concentrations were significantly elevated following disinhibition of neurons in the RVLM, they were unchanged by inhibition of neurons in the CVLM. These results demonstrate that the discharge of sympathetic premotor neurons in the RVLM regulating adrenal secretion of EPI is modulated by a tonic, GABA-ergic inhibition that arises from a source that is different from the sympathoinhibitory neurons in the CVLM that project to RVLM sympathetic premotor neurons controlling vasoconstrictor and cardiac targets.

Original languageEnglish (US)
Pages (from-to)169-175
Number of pages7
JournalBrain Research
Volume827
Issue number1-2
DOIs
StatePublished - May 8 1999
Externally publishedYes

Fingerprint

Epinephrine
Neurons
Muscimol
Chloralose
Adrenal Medulla
Bicuculline
Urethane
Microinjections
Vasoconstrictor Agents
gamma-Aminobutyric Acid
Norepinephrine
Arterial Pressure
Heart Rate

Keywords

  • Arterial blood pressure
  • Bicuculline
  • Muscimol
  • Plasma catecholamine
  • Rostral ventrolateral medulla
  • Sympathetic nerve activity

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

Adrenal epinephrine secretion is not regulated by sympathoinhibitory neurons in the caudal ventrolateral medulla. / Natarajan, Madhusudan; Morrison, Shaun.

In: Brain Research, Vol. 827, No. 1-2, 08.05.1999, p. 169-175.

Research output: Contribution to journalArticle

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