Role of the locus ceruleus in baroreceptor regulation of supraoptic vasopressin neurons in the rat

Ryan J. Grindstaff, Regina R. Grindstaff, Margaret J. Sullivan, Joseph Thomas Cunningham

Research output: Contribution to journalArticle

33 Citations (Scopus)

Abstract

The goal of this study was to identify the source of baroreceptor-related noradrenergic innervation of the diagonal band of Broca (DBB). Male Sprague-Dawley rats underwent sinoaortic denervation (SAD, n = 13) or sham SAD surgery (n = 13). We examined Fos expression produced by baroreceptor activation and dopamine-β-hydroxylase immunofluorescence in hindbrain regions that contain noradrenergic neurons. Baroreceptors were stimulated by increasing blood pressure >40 mmHg with phenylephrine (10 μg · kg-1 · min-1 iv) in sham SAD and SAD rats. Controls were infused with 0.9% saline. Only the locus ceruleus (LC) demonstrated a baroreceptor-dependent increase in Fos immunoreactivity in dopamine-β-hydroxylase-positive neurons. In a second experiment, normal rats received rhodamine-labeled microsphere injections in the DBB (n = 12) before phenylephrine or vehicle infusion. In these experiments, only the LC consistently contained Fos-positive cells after phenylephrine infusion that were retrogradely labeled from the DBB. Finally, we lesioned the LC with ibotenic acid and obtained extracellular recordings from identified vasopressin neurons in the supraoptic nucleus. LC lesions significantly reduced the number of vasopressin neurons that were inhibited by acute baroreceptor stimulation. Together, these results suggest that noradrenergic neurons in the LC participate in the baroreflex activation of the DBB and may thus be important in the baroreflex inhibition of vasopressin-releasing neurons in the supraoptic nucleus.

Original languageEnglish
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume279
Issue number1 48-1
StatePublished - 29 Aug 2000

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Pressoreceptors
Diagonal Band of Broca
Locus Coeruleus
Vasopressins
Neurons
Phenylephrine
Adrenergic Neurons
Supraoptic Nucleus
Baroreflex
Mixed Function Oxygenases
Dopamine
Ibotenic Acid
Rhombencephalon
Rhodamines
Denervation
Microspheres
Fluorescent Antibody Technique
Sprague Dawley Rats
Blood Pressure
Injections

Keywords

  • Fos
  • Sinoaortic deafferentation
  • Supraoptic nucleus

Cite this

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abstract = "The goal of this study was to identify the source of baroreceptor-related noradrenergic innervation of the diagonal band of Broca (DBB). Male Sprague-Dawley rats underwent sinoaortic denervation (SAD, n = 13) or sham SAD surgery (n = 13). We examined Fos expression produced by baroreceptor activation and dopamine-β-hydroxylase immunofluorescence in hindbrain regions that contain noradrenergic neurons. Baroreceptors were stimulated by increasing blood pressure >40 mmHg with phenylephrine (10 μg · kg-1 · min-1 iv) in sham SAD and SAD rats. Controls were infused with 0.9{\%} saline. Only the locus ceruleus (LC) demonstrated a baroreceptor-dependent increase in Fos immunoreactivity in dopamine-β-hydroxylase-positive neurons. In a second experiment, normal rats received rhodamine-labeled microsphere injections in the DBB (n = 12) before phenylephrine or vehicle infusion. In these experiments, only the LC consistently contained Fos-positive cells after phenylephrine infusion that were retrogradely labeled from the DBB. Finally, we lesioned the LC with ibotenic acid and obtained extracellular recordings from identified vasopressin neurons in the supraoptic nucleus. LC lesions significantly reduced the number of vasopressin neurons that were inhibited by acute baroreceptor stimulation. Together, these results suggest that noradrenergic neurons in the LC participate in the baroreflex activation of the DBB and may thus be important in the baroreflex inhibition of vasopressin-releasing neurons in the supraoptic nucleus.",
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Role of the locus ceruleus in baroreceptor regulation of supraoptic vasopressin neurons in the rat. / Grindstaff, Ryan J.; Grindstaff, Regina R.; Sullivan, Margaret J.; Cunningham, Joseph Thomas.

In: American Journal of Physiology - Regulatory Integrative and Comparative Physiology, Vol. 279, No. 1 48-1, 29.08.2000.

Research output: Contribution to journalArticle

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