Evidence for a GABAergic projection from the central nucleus of the amygdala to the brainstem of the macaque monkey: A combined retrograde tracing and in situ hybridization study

Ana L. Jongen-Rêlo, David G Amaral

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Abstract

The central nucleus of the amygdala is interconnected with a variety of visceral and autonomic nuclei of the brainstem. These include the parabrachial nucleus, the nucleus of the solitary tract, the nucleus ambiguus and the dorsal motor nucleus of the vagus. Despite repeated attempts, neurochemical characterization of the major subcortical connections of the central nucleus has not yet been accomplished. Based on earlier immunohistochemical and in situ hybridization evidence indicating the presence of numerous GABAergic neurons in the macaque monkey central nucleus, we predicted that a sizeable portion of the descending projections may be GABAergic. We tested this hypothesis using a novel double labelling method with gold conjugated WGA-apoHRP as a retrograde tracer and in situ hybridization for detecting the mRNA that encodes the enzyme glutamic acid decarboxylase (GAD67) as a marker for GABAergic cells. Following WGA-apoHRP-gold injections into the brainstem, a large number of retrogradely labelled cells was observed in the medial and lateral divisions of the central nucleus. Of the retrogradely labelled cells observed in the medial division of the central nucleus, approximately half were double-labelled for GAD67 mRNA; about 30% double labelling was observed in the lateral division. These data support the view that a sizeable component of the central nucleus projection to the brainstem is GABAergic.

Original languageEnglish (US)
Pages (from-to)2924-2933
Number of pages10
JournalEuropean Journal of Neuroscience
Volume10
Issue number9
DOIs
StatePublished - 1998

Fingerprint

Macaca
Intralaminar Thalamic Nuclei
Brain Stem
Haplorhini
In Situ Hybridization
Solitary Nucleus
GABAergic Neurons
Medulla Oblongata
Messenger RNA
Glutamate Decarboxylase
Injections
Enzymes
Central Amygdaloid Nucleus
wheat germ agglutinin-apohorseradish peroxidase conjugate gold complex

Keywords

  • Connections
  • Dorsal motor nucleus of the vagus
  • GABA
  • GAD67-mRNA
  • Nucleus ambiguus
  • Parabrachial nucleus
  • WGA-apoHRP-gold

ASJC Scopus subject areas

  • Neuroscience(all)

Cite this

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abstract = "The central nucleus of the amygdala is interconnected with a variety of visceral and autonomic nuclei of the brainstem. These include the parabrachial nucleus, the nucleus of the solitary tract, the nucleus ambiguus and the dorsal motor nucleus of the vagus. Despite repeated attempts, neurochemical characterization of the major subcortical connections of the central nucleus has not yet been accomplished. Based on earlier immunohistochemical and in situ hybridization evidence indicating the presence of numerous GABAergic neurons in the macaque monkey central nucleus, we predicted that a sizeable portion of the descending projections may be GABAergic. We tested this hypothesis using a novel double labelling method with gold conjugated WGA-apoHRP as a retrograde tracer and in situ hybridization for detecting the mRNA that encodes the enzyme glutamic acid decarboxylase (GAD67) as a marker for GABAergic cells. Following WGA-apoHRP-gold injections into the brainstem, a large number of retrogradely labelled cells was observed in the medial and lateral divisions of the central nucleus. Of the retrogradely labelled cells observed in the medial division of the central nucleus, approximately half were double-labelled for GAD67 mRNA; about 30{\%} double labelling was observed in the lateral division. These data support the view that a sizeable component of the central nucleus projection to the brainstem is GABAergic.",
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