Alpha‐2A‐adrenergic receptors are present on neurons in the central nucleus of the amygdala that project to the dorsal vagal complex in the rat

Alpha‐2A‐adrenergic receptors are present on neurons in the central nucleus of the amygdala... The descending pathway between the central nucleus of the amygdala (CeA) and the dorsal vagal complex (DVC) is an important substrate for autonomic functions associated with emotion. Activity in this circuit is crucially modulated by catecholamines and agonists of the alpha‐2A‐adrenergic receptor (α2A‐AR), which relieve cardiovascular and gastrointestinal symptoms associated with experience of aversive stimuli. The subcellular distribution of α2A‐AR within the CeA, however, has not been characterized. It is also not known if any α2A‐AR‐expressing neurons in the CeA project to the dorsal vagal complex. In order to address these questions, we examined the immunocytochemical labeling of α2A‐AR in the CeA of rats receiving microinjection of the retrograde tracer fluorogold (FG) into the dorsal vagal complex at the level of the area postrema, an area involved in cardiorespiratory and gastrointestinal functions. Of all α2A‐AR‐labeled profiles in the CeA, the majority were either dendrites (42%) or somata (24%). α2A‐AR labeling was often present on the plasmalemma in dendrites and was mainly found in endosome‐like organelles in somata. Of all α2A‐AR immunoreactive somata, 62% also contained immunolabeling for FG and 23% of all dendrites also showed labeling for the retrograde tracer. The intracellular distribution of α2A‐AR did not differ in somata or dendrites with or without detectable FG. The remaining singly labeled α2A‐AR profiles consisted of axons (11%), axon terminals (12%), and glial processes (13%). In numerous instances, α2A‐AR‐labeled glia or axon terminals were apposed to DVC projecting neurons. Together, this evidence suggests that the principal site for α2A‐AR activation is at extrasynaptic sites on dendrites of CeA neurons, many of which project to the DVC and also show endosomal receptor labeling. In addition, these results indicate that activation of α2A‐AR in the CeA may influence the activity of DVC projecting neurons through indirect mechanisms, including changes in presynaptic transmitter release or glial function. These results suggest that α2A‐AR agonists in the CeA may modulate numerous processes including stress‐evoked autonomic reactions and feeding behavior. Synapse 46:258–268, 2002. © 2002 Wiley‐Liss, Inc. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Synapse Wiley

Alpha‐2A‐adrenergic receptors are present on neurons in the central nucleus of the amygdala that project to the dorsal vagal complex in the rat

Loading next page...
 
/lp/wiley/alpha-2a-adrenergic-receptors-are-present-on-neurons-in-the-central-1h3jDq5woQ
Publisher
Wiley
Copyright
Copyright © 2002 Wiley‐Liss, Inc.
ISSN
0887-4476
eISSN
1098-2396
DOI
10.1002/syn.10136
pmid
12373741
Publisher site
See Article on Publisher Site

Abstract

The descending pathway between the central nucleus of the amygdala (CeA) and the dorsal vagal complex (DVC) is an important substrate for autonomic functions associated with emotion. Activity in this circuit is crucially modulated by catecholamines and agonists of the alpha‐2A‐adrenergic receptor (α2A‐AR), which relieve cardiovascular and gastrointestinal symptoms associated with experience of aversive stimuli. The subcellular distribution of α2A‐AR within the CeA, however, has not been characterized. It is also not known if any α2A‐AR‐expressing neurons in the CeA project to the dorsal vagal complex. In order to address these questions, we examined the immunocytochemical labeling of α2A‐AR in the CeA of rats receiving microinjection of the retrograde tracer fluorogold (FG) into the dorsal vagal complex at the level of the area postrema, an area involved in cardiorespiratory and gastrointestinal functions. Of all α2A‐AR‐labeled profiles in the CeA, the majority were either dendrites (42%) or somata (24%). α2A‐AR labeling was often present on the plasmalemma in dendrites and was mainly found in endosome‐like organelles in somata. Of all α2A‐AR immunoreactive somata, 62% also contained immunolabeling for FG and 23% of all dendrites also showed labeling for the retrograde tracer. The intracellular distribution of α2A‐AR did not differ in somata or dendrites with or without detectable FG. The remaining singly labeled α2A‐AR profiles consisted of axons (11%), axon terminals (12%), and glial processes (13%). In numerous instances, α2A‐AR‐labeled glia or axon terminals were apposed to DVC projecting neurons. Together, this evidence suggests that the principal site for α2A‐AR activation is at extrasynaptic sites on dendrites of CeA neurons, many of which project to the DVC and also show endosomal receptor labeling. In addition, these results indicate that activation of α2A‐AR in the CeA may influence the activity of DVC projecting neurons through indirect mechanisms, including changes in presynaptic transmitter release or glial function. These results suggest that α2A‐AR agonists in the CeA may modulate numerous processes including stress‐evoked autonomic reactions and feeding behavior. Synapse 46:258–268, 2002. © 2002 Wiley‐Liss, Inc.

Journal

SynapseWiley

Published: Dec 15, 2002

References

  • Anatomical substrates for baroreflex sympathoinhibition in the rat
    Aicher, Aicher; Milner, Milner; Pickel, Pickel; Reis, Reis
  • Regulation of signal transduction by endocytosis
    Ceresa, Ceresa; Schmid, Schmid
  • Induction and adaptation of Fos expression in the rat brain by two types of acute restraint stress
    Chowdhury, Chowdhury; Fujioka, Fujioka; Nakamura, Nakamura
  • Tonic GABA(A) receptor‐mediated neurotransmission in the dorsal vagal complex regulates intestinal motility in rats
    Greenwood‐Van Meerveld, Greenwood‐Van Meerveld; Barron, Barron
  • Influence of GABA in the nucleus of the solitary tract on blood pressure in baroreceptor‐denervated rats
    Ito, Ito; Sved, Sved
  • Neurochemical modulation of cardiovascular control in the nucleus tractus solitarius
    Lawrence, Lawrence; Jarrott, Jarrott
  • Emotion circuits in the brain
    LeDoux, LeDoux
  • GABAergic neurons in rat nuclei of solitary tracts receive inhibitory‐type synapses from amygdaloid efferents lacking detectable GABA‐immunoreactivity
    Pickel, Pickel; Van Bockstaele, Van Bockstaele; Chan, Chan; Cestari, Cestari
  • Vagal circuitry mediating cephalic‐phase responses to food
    Powley, Powley

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create folders to
organize your research

Export folders, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off