title: Neurochemical properties of the synapses between the parabrachial nucleus-derived CGRP-positive axonal terminals and the GABAergic neurons in the lateral capsular division of central nucleus of amygdala.
abstract: The lateral capsular division of central nucleus of amygdala (CeC) contains neurons using γ-amino butyric acid (GABA) as the predominant neurotransmitter and expresses abundant calcitonin gene-related peptide (CGRP)-positive terminals. However, the relationship between them has not been revealed yet. Using GAD67-green fluorescent protein (GFP) knock-in mouse, we investigated the neurochemical features of synapses between CGRP-positive terminals and GABAergic neurons within CeC and the potential involvement of CGRP1 receptor by combining fluorescent in situ hybridization for CGRP1 receptor mRNA with immunofluorescent histochemistry for GFP and CGRP. The ultrastructures of these synapses were investigated with pre-embedding electron microscopy for GFP and CGRP. We found that some GABAergic neurons in the CeC received parabrachial nucleus (PBN) derived CGRP innervations and some of these GABAergic neurons can be activated by subcutaneous injection of formalin. Moreover, more than 90 % GABAergic neurons innervated by CGRP-positive terminal also express CGRP1 receptor mRNA. The CGRP-positive fibers made symmetric synapses onto the GABAergic somata, and asymmetric synapses onto the GABA-LI dendritic shafts and spines. This study provides direct ultrastructural evidences for the synaptic contacts between CGRP-positive terminals and GABAergic neurons within the CeC, which may underlie the pain-related neural pathway from PBN to CeC and be involved in the chronic pain modulation.
authors.affiliation: Department of Anatomy, Histology and Embryology and K.K. Leung Brain Research Centre, The Fourth Military Medical University, Xi'an, 710032, People's Republic of China.
authors.forename: Ya-Cheng
authors.initials: YC
authors.lastname: Lu
authors.forename: Yan-Zhou
authors.initials: YZ
authors.lastname: Chen
authors.forename: Yan-Yan
authors.initials: YY
authors.lastname: Wei
authors.forename: Xiao-Tao
authors.initials: XT
authors.lastname: He
authors.forename: Xia
authors.initials: X
authors.lastname: Li
authors.forename: Wei
authors.initials: W
authors.lastname: Hu
authors.forename: Yuchio
authors.initials: Y
authors.lastname: Yanagawa
authors.forename: Wen
authors.initials: W
authors.lastname: Wang
authors.forename: Sheng-Xi
authors.initials: SX
authors.lastname: Wu
authors.forename: Yu-Lin
authors.initials: YL
authors.lastname: Dong
mesh_terms: D000818:Animals; D015740:Calcitonin Gene-Related Peptide / Q000378:metabolism*; D066274:Central Amygdaloid Nucleus / Q000378:metabolism* / Q000648:ultrastructure; D005455:Fluorescent Antibody Technique; D059330:GABAergic Neurons / Q000378:metabolism*; D049452:Green Fluorescent Proteins / Q000378:metabolism; D007249:Inflammation / Q000473:pathology; D008297:Male; D051379:Mice; D059225:Nociception; D010146:Pain / Q000473:pathology; D065823:Parabrachial Nucleus / Q000378:metabolism*; D017729:Presynaptic Terminals / Q000378:metabolism* / Q000648:ultrastructure; D018015:Receptors, Calcitonin Gene-Related Peptide / Q000378:metabolism; D013569:Synapses / Q000737:chemistry* / Q000378:metabolism / Q000648:ultrastructure
chemical_list: D018015:Receptors, Calcitonin Gene-Related Peptide; D049452:Green Fluorescent Proteins; D015740:Calcitonin Gene-Related Peptide