Long-lasting inhibition of the cardiovascular responses to glutamate and the baroreceptor reflex elicited by neuropeptide Y injected into the nucleus tractus solitarius of the rat

Lars Grundemar, Claes Wahlestedt, Donald J. Reis

Research output: Contribution to journalArticle

49 Scopus citations

Abstract

Neuropeptide Y (NPY) microinjected unilaterally into the nucleus tractus solitarii (NTS) of anesthetized paralyzed rats elicits a gradual dose-dependent and reversible fall in arterial pressure (AP) and heart rate (HR) lasting 20 min. It also abolished the brief (<1 min) dose-dependent and reversible fall of AP and HR elicited by l-glutamate (l-Glu) injected into the nucleus. The blockade of l-Glu by NPY appeared gradually and was prolonged, lasting over 2 h, and recovering by 24 h. It was not replicated by desamido-NPY or galanin. Unlike 2% lidocaine it did not block the hypotension elicited by focal electrical stimulation at the injection site indicating the response was not that of a local anesthetic. Bilateral injection of NPY into the NTS resulted, after an initial fall, in an elevation of AP (+48±10.6 mmHg). At this time the reflex bradycardia evoked by elevating AP with phenylephrine was markedly reduced. We conclude that in the NTS, NPY antagonizes the actions of l-Glu and may attenuate baroreceptor reflexes. Since the NTS is richly innervated by NPY neurons and contains many NPY binding sites and since primary baroreceptor afferents appear to be glutamatergic the results suggested that NPY may serve in NTS as a long-term regulator of baroreceptor reflex activity.

Original languageEnglish (US)
Pages (from-to)135-139
Number of pages5
JournalNeuroscience Letters
Volume122
Issue number1
DOIs
StatePublished - Jan 14 1991
Externally publishedYes

Keywords

  • Arterial pressure
  • Baroreceptor
  • Galanin
  • Heart rate
  • l-Glutamate
  • Neuropeptide Y
  • Nucleus tractus solitarii

ASJC Scopus subject areas

  • Neuroscience(all)

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