Gigantocellular vasodepressor area is tonically active and distinct from caudal ventrolateral vasodepressor area

Sue Aicher, Donald J. Reis

Research output: Contribution to journalArticle

15 Citations (Scopus)

Abstract

The gigantocellular depressor area (GiDA) is a functionally defined subdivision of the medullary gigantocellular reticular formation where vasodepressor responses are evoked by glutamate microinjections (Aicher, S. A., D. J. Reis, D. A. Ruggiero, and T. A. Milner. Neuroscience 60: 761-779, 1994). The present experiments sought to determine whether the GiDA 1) tonically inhibits the sympathetic nervous system; 2) is necessary for baroreflex function; and 3) is functionally distinct from adjacent vasodepressor regions in the medullary reticular formation, including the midline raphe nuclei and the caudal ventrolateral medulla (CVL). Excitotoxic lesions of the GiDA abolished the baroreflex and significantly increased sympathetic nerve activity in anesthetized rats. Equivalent injections into the midline raphe nuclei elevated sympathetic activity but did not alter baroreflex responses. Therefore, the GiDA is functionally distinct from the raphe nuclei, although both contain tonically active sympathoinhibitory neurons. Because the effects of GiDA lesions were identical to those seen after lesions of the CVL, further studies were required to demonstrate that the GiDA and CVL are functionally and anatomically distinct. First, intramedullary injections of kynurenic acid produced hypertension and blocked the baroreflex when placed in the CVL, but not when placed in the GiDA. Second, muscimol inactivation of the RVL blocked the hypertension produced by excitotoxic lesions of the CVL, but failed to block the hypertension produced by similar lesions of the GiDA. Third, CVL neurons project to the RVL but not the spinal cord, whereas GiDA neurons project to the spinal cord but not the RVL. These studies show that the CVL and GiDA are both tonically sympathoinhibitory regions, but they are distinct with regard to their functional connectivity with other autonomic regions.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Regulatory Integrative and Comparative Physiology
Volume272
Issue number3 41-3
StatePublished - Mar 1997
Externally publishedYes

Fingerprint

Baroreflex
Raphe Nuclei
Reticular Formation
Hypertension
Neurons
Spinal Cord
Kynurenic Acid
Muscimol
Injections
Sympathetic Nervous System
Microinjections
Neurosciences
Glutamic Acid

Keywords

  • baroreflex function
  • cardiovascular regulation
  • rat
  • reticular formation
  • reticulospinal neurons

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)

Cite this

@article{3c88b880be8441ec9f8263e779d77303,
title = "Gigantocellular vasodepressor area is tonically active and distinct from caudal ventrolateral vasodepressor area",
abstract = "The gigantocellular depressor area (GiDA) is a functionally defined subdivision of the medullary gigantocellular reticular formation where vasodepressor responses are evoked by glutamate microinjections (Aicher, S. A., D. J. Reis, D. A. Ruggiero, and T. A. Milner. Neuroscience 60: 761-779, 1994). The present experiments sought to determine whether the GiDA 1) tonically inhibits the sympathetic nervous system; 2) is necessary for baroreflex function; and 3) is functionally distinct from adjacent vasodepressor regions in the medullary reticular formation, including the midline raphe nuclei and the caudal ventrolateral medulla (CVL). Excitotoxic lesions of the GiDA abolished the baroreflex and significantly increased sympathetic nerve activity in anesthetized rats. Equivalent injections into the midline raphe nuclei elevated sympathetic activity but did not alter baroreflex responses. Therefore, the GiDA is functionally distinct from the raphe nuclei, although both contain tonically active sympathoinhibitory neurons. Because the effects of GiDA lesions were identical to those seen after lesions of the CVL, further studies were required to demonstrate that the GiDA and CVL are functionally and anatomically distinct. First, intramedullary injections of kynurenic acid produced hypertension and blocked the baroreflex when placed in the CVL, but not when placed in the GiDA. Second, muscimol inactivation of the RVL blocked the hypertension produced by excitotoxic lesions of the CVL, but failed to block the hypertension produced by similar lesions of the GiDA. Third, CVL neurons project to the RVL but not the spinal cord, whereas GiDA neurons project to the spinal cord but not the RVL. These studies show that the CVL and GiDA are both tonically sympathoinhibitory regions, but they are distinct with regard to their functional connectivity with other autonomic regions.",
keywords = "baroreflex function, cardiovascular regulation, rat, reticular formation, reticulospinal neurons",
author = "Sue Aicher and Reis, {Donald J.}",
year = "1997",
month = "3",
language = "English (US)",
volume = "272",
journal = "American Journal of Physiology - Renal Fluid and Electrolyte Physiology",
issn = "1931-857X",
publisher = "American Physiological Society",
number = "3 41-3",

}

TY - JOUR

T1 - Gigantocellular vasodepressor area is tonically active and distinct from caudal ventrolateral vasodepressor area

AU - Aicher, Sue

AU - Reis, Donald J.

PY - 1997/3

Y1 - 1997/3

N2 - The gigantocellular depressor area (GiDA) is a functionally defined subdivision of the medullary gigantocellular reticular formation where vasodepressor responses are evoked by glutamate microinjections (Aicher, S. A., D. J. Reis, D. A. Ruggiero, and T. A. Milner. Neuroscience 60: 761-779, 1994). The present experiments sought to determine whether the GiDA 1) tonically inhibits the sympathetic nervous system; 2) is necessary for baroreflex function; and 3) is functionally distinct from adjacent vasodepressor regions in the medullary reticular formation, including the midline raphe nuclei and the caudal ventrolateral medulla (CVL). Excitotoxic lesions of the GiDA abolished the baroreflex and significantly increased sympathetic nerve activity in anesthetized rats. Equivalent injections into the midline raphe nuclei elevated sympathetic activity but did not alter baroreflex responses. Therefore, the GiDA is functionally distinct from the raphe nuclei, although both contain tonically active sympathoinhibitory neurons. Because the effects of GiDA lesions were identical to those seen after lesions of the CVL, further studies were required to demonstrate that the GiDA and CVL are functionally and anatomically distinct. First, intramedullary injections of kynurenic acid produced hypertension and blocked the baroreflex when placed in the CVL, but not when placed in the GiDA. Second, muscimol inactivation of the RVL blocked the hypertension produced by excitotoxic lesions of the CVL, but failed to block the hypertension produced by similar lesions of the GiDA. Third, CVL neurons project to the RVL but not the spinal cord, whereas GiDA neurons project to the spinal cord but not the RVL. These studies show that the CVL and GiDA are both tonically sympathoinhibitory regions, but they are distinct with regard to their functional connectivity with other autonomic regions.

AB - The gigantocellular depressor area (GiDA) is a functionally defined subdivision of the medullary gigantocellular reticular formation where vasodepressor responses are evoked by glutamate microinjections (Aicher, S. A., D. J. Reis, D. A. Ruggiero, and T. A. Milner. Neuroscience 60: 761-779, 1994). The present experiments sought to determine whether the GiDA 1) tonically inhibits the sympathetic nervous system; 2) is necessary for baroreflex function; and 3) is functionally distinct from adjacent vasodepressor regions in the medullary reticular formation, including the midline raphe nuclei and the caudal ventrolateral medulla (CVL). Excitotoxic lesions of the GiDA abolished the baroreflex and significantly increased sympathetic nerve activity in anesthetized rats. Equivalent injections into the midline raphe nuclei elevated sympathetic activity but did not alter baroreflex responses. Therefore, the GiDA is functionally distinct from the raphe nuclei, although both contain tonically active sympathoinhibitory neurons. Because the effects of GiDA lesions were identical to those seen after lesions of the CVL, further studies were required to demonstrate that the GiDA and CVL are functionally and anatomically distinct. First, intramedullary injections of kynurenic acid produced hypertension and blocked the baroreflex when placed in the CVL, but not when placed in the GiDA. Second, muscimol inactivation of the RVL blocked the hypertension produced by excitotoxic lesions of the CVL, but failed to block the hypertension produced by similar lesions of the GiDA. Third, CVL neurons project to the RVL but not the spinal cord, whereas GiDA neurons project to the spinal cord but not the RVL. These studies show that the CVL and GiDA are both tonically sympathoinhibitory regions, but they are distinct with regard to their functional connectivity with other autonomic regions.

KW - baroreflex function

KW - cardiovascular regulation

KW - rat

KW - reticular formation

KW - reticulospinal neurons

UR - http://www.scopus.com/inward/record.url?scp=0030975762&partnerID=8YFLogxK

UR - http://www.scopus.com/inward/citedby.url?scp=0030975762&partnerID=8YFLogxK

M3 - Article

C2 - 9087634

AN - SCOPUS:0030975762

VL - 272

JO - American Journal of Physiology - Renal Fluid and Electrolyte Physiology

JF - American Journal of Physiology - Renal Fluid and Electrolyte Physiology

SN - 1931-857X

IS - 3 41-3

ER -