Behavioral and physiological studies have implicated the central nucleus of the amygdala (CNA) in the motoric (both somatic and visceral) expression of fear behavior. Anatomically, the CNA is well situated to modulate information concerning the external and internal environment, via limbic cortices, amygdala and hypothalamus, and to affect autonomic and somatc behavior via projections to the basal forebrain, ventral mid-brain and brain stem. The distribution pattern of cortical afferent termination in the CNA is poorly understood though the available evidence indicates that these afferents terminate in specific cytoarchitectonic zones. This may reflect specific interactions with efferent projection neuron populations in the CNA that likewise show highly specific distributions. Moreover, terminals containing met-enkephalin and pro-opiomelanocortin (POMC) derived peptides are distributed over specific parts of the CNA. Preliminary studies suggest that these distribution patterns are congruent with both the distribution of certain cortical afferents and with specific populations of projection neurons. The proposed investigations are designed to test the applicant's hypotheses that (a) cortical afferents that show nonoverlapping distributions in the CNA innervate different populations of projection neurons and (b) that met-enkephalin and POMC peptides interact with cortical afferents contacting similar projection neurons. Results may lead to a better understanding of how the CNA processes cortical information and how endogenous peptides (and drugs that mimic/block these peptides) influence behavior. The distribution of cortical afferents in the CNA will be determined using the anterograde transport of peroxidase conjugated lectins. Data will be correlated with the applicant's previous work on the distributions of projection neurons in the CNA. Evidence of direct cortical innervation of CNA projection neurons and interactions with terminals containing met-enkephalin and POMC peptides will be sought at the ultrastructural level using combined lesion-induced degeneration of cortical afferents, peptide immunocytochemistry and retrograde transport of horseradish peroxidase from focal injections into the medulla and basal forebrain.

Agency
National Institute of Health (NIH)
Institute
National Institute of Neurological Disorders and Stroke (NINDS)
Type
First Independent Research Support & Transition (FIRST) Awards (R29)
Project #
5R29NS025139-05
Application #
3477012
Study Section
Neurology A Study Section (NEUA)
Project Start
1987-07-01
Project End
1992-06-30
Budget Start
1991-07-01
Budget End
1992-06-30
Support Year
5
Fiscal Year
1991
Total Cost
Indirect Cost
Name
University of Iowa
Department
Type
Schools of Medicine
DUNS #
041294109
City
Iowa City
State
IA
Country
United States
Zip Code
52242
Sun, N; Yi, H; Cassell, M D (1994) Evidence for a GABAergic interface between cortical afferents and brainstem projection neurons in the rat central extended amygdala. J Comp Neurol 340:43-64
Davis, M; Rainnie, D; Cassell, M (1994) Neurotransmission in the rat amygdala related to fear and anxiety. Trends Neurosci 17:208-14
Sun, N; Cassell, M D (1993) Intrinsic GABAergic neurons in the rat central extended amygdala. J Comp Neurol 330:381-404
Freedman, L J; Yi, H (1993) Confocal imaging of the retrograde tracer fluoro-gold using a non-ultraviolet laser. Brain Res Bull 31:749-51
Shi, C; Cassell, M D (1993) Combination of intracellular staining of retrogradely labeled neurons and anterograde fluorescent tracing: use of the confocal laser scanning microscope. J Neurosci Methods 47:23-31
Sun, N; Roberts, L; Cassell, M D (1991) Rat central amygdaloid nucleus projections to the bed nucleus of the stria terminalis. Brain Res Bull 27:651-62
Cassell, M D; Roberts, L (1991) Ultrastructural evidence for an olfactory-autonomic pathway through the rat central amygdaloid nucleus. Neurosci Lett 133:100-4
Cassell, M D; Gray, T S (1989) Morphology of peptide-immunoreactive neurons in the rat central nucleus of the amygdala. J Comp Neurol 281:320-33
Thompson, R L; Cassell, M D (1989) Differential distribution and non-collateralization of central amygdaloid neurons projecting to different medullary regions. Neurosci Lett 97:245-51
Cassell, M D; Gray, T S (1989) The amygdala directly innervates adrenergic (C1) neurons in the ventrolateral medulla in the rat. Neurosci Lett 97:163-8

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