title: Structural and functional characterization of dendritic arbors and GABAergic synaptic inputs on interneurons and principal cells in the rat basolateral amygdala.
abstract: The basolateral amygdala (BLA) is a complex brain region associated with processing emotional states, such as fear, anxiety, and stress. Some aspects of these emotional states are driven by the network activity of synaptic connections, derived from both local circuitry and projections to the BLA from other regions. Although the synaptic physiology and general morphological characteristics are known for many individual cell types within the BLA, the combination of morphological, electrophysiological, and distribution of neurochemical GABAergic synapses in a three-dimensional neuronal arbor has not been reported for single neurons from this region. The aim of this study was to assess differences in morphological characteristics of BLA principal cells and interneurons, quantify the distribution of GABAergic neurochemical synapses within the entire neuronal arbor of each cell type, and determine whether GABAergic synaptic density correlates with electrophysiological recordings of inhibitory postsynaptic currents. We show that BLA principal neurons form complex dendritic arborizations, with proximal dendrites having fewer spines but higher densities of neurochemical GABAergic synapses compared with distal dendrites. Furthermore, we found that BLA interneurons exhibited reduced dendritic arbor lengths and spine densities but had significantly higher densities of putative GABAergic synapses compared with principal cells, which was correlated with an increased frequency of spontaneous inhibitory postsynaptic currents. The quantification of GABAergic connectivity, in combination with morphological and electrophysiological measurements of the BLA cell types, is the first step toward a greater understanding of how fear and stress lead to changes in morphology, local connectivity, and/or synaptic reorganization of the BLA.
authors.affiliation: Translational Research Institute and Institute for Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia;
authors.forename: Paul M
authors.initials: PM
authors.lastname: Klenowski
authors.affiliation: School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia; and.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Fogarty
authors.affiliation: Translational Research Institute and Institute for Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia;
authors.forename: Arnauld
authors.initials: A
authors.lastname: Belmer
authors.affiliation: School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia; and Queensland Brain Institute, The University of Queensland, Brisbane, Queensland, Australia.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Noakes
authors.affiliation: School of Biomedical Sciences, The University of Queensland, Brisbane, Queensland, Australia; and.
authors.forename: Mark C
authors.initials: MC
authors.lastname: Bellingham
authors.affiliation: Translational Research Institute and Institute for Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Queensland, Australia; selena.bartlett@qut.edu.au.
authors.forename: Selena E
authors.initials: SE
authors.lastname: Bartlett
mesh_terms: D000818:Animals; D066272:Basolateral Nuclear Complex / Q000166:cytology* / Q000502:physiology; D048429:Cell Size; D003712:Dendrites / Q000502:physiology*; D021621:Imaging, Three-Dimensional; D007150:Immunohistochemistry; D053444:Inhibitory Postsynaptic Potentials / Q000502:physiology*; D007395:Interneurons / Q000166:cytology* / Q000502:physiology; D008297:Male; D018613:Microscopy, Confocal; D018408:Patch-Clamp Techniques; D017208:Rats, Wistar; D013569:Synapses / Q000502:physiology*; D046509:Tissue Culture Techniques; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D005680:gamma-Aminobutyric Acid
keywords: GABA; basolateral amygdala; dendritic spines; synaptic currents