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Morphological and physiological evidence of a synaptic connection between the lateral parabrachial nucleus and neurons in the A7 catecholamine cell group in rats

BACKGROUND: The descending noradrenergic (NAergic) system is one of the important endogenous analgesia systems. It has been suggested that noxious stimuli could activate descending NAergic system; nevertheless, the underlying neuronal circuit remains unclear. As NAergic neurons in the A7 catecholami...

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Autores principales: Liu, Chia-Yi, Lee, Meng-Lam, Yang, Chi-Sheng, Chen, Chuan-Mu, Min, Ming-Yuan, Yang, Hsiu-Wen
Formato: Online Artículo Texto
Lenguaje:English
Publicado: BioMed Central 2015
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4575445/
https://www.ncbi.nlm.nih.gov/pubmed/26385355
http://dx.doi.org/10.1186/s12929-015-0179-2
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author Liu, Chia-Yi
Lee, Meng-Lam
Yang, Chi-Sheng
Chen, Chuan-Mu
Min, Ming-Yuan
Yang, Hsiu-Wen
author_facet Liu, Chia-Yi
Lee, Meng-Lam
Yang, Chi-Sheng
Chen, Chuan-Mu
Min, Ming-Yuan
Yang, Hsiu-Wen
author_sort Liu, Chia-Yi
collection PubMed
description BACKGROUND: The descending noradrenergic (NAergic) system is one of the important endogenous analgesia systems. It has been suggested that noxious stimuli could activate descending NAergic system; nevertheless, the underlying neuronal circuit remains unclear. As NAergic neurons in the A7 catecholamine cell group (A7) are a part of the descending NAergic system and the lateral parabrachial nucleus (LPB) is an important brainstem structure that relays ascending nociceptive signal, we aimed to test whether LPB neurons have direct synaptic contact with NAergic A7 neurons. RESULTS: Stereotaxic injections of an anterograde tracer, biotinylated dextran-amine (BDA), were administered to LPB in rats. The BDA-labeled axonal terminals that have physical contacts with tyrosine hydroxylase-positive (presumed noadrenergic) neurons were identified in A7. Consistent with these morphological observations, the excitatory synaptic currents (EPSCs) were readily evoked in NAergic A7 neurons by extracellular stimulation of LPB. The EPSCs evoked by LPB stimulation were blocked by CNQX, a non-NMDA receptor blocker, and AP5, a selective NMDA receptor blocker, showing that LPB-A7 synaptic transmission is glutamatergic. Moreover, the amplitude of LPB-A7 EPSCs was significantly attenuated by DAMGO, a selective μ-opioid receptor agonist, which was associated with an increase in paired-pulse ratio. CONCLUSIONS: Taken together, the above results showed direct synaptic connections between LPB and A7 catecholamine cell group, the function of which is subject to presynaptic modulation by μ-opioid receptors.
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spelling pubmed-45754452015-09-20 Morphological and physiological evidence of a synaptic connection between the lateral parabrachial nucleus and neurons in the A7 catecholamine cell group in rats Liu, Chia-Yi Lee, Meng-Lam Yang, Chi-Sheng Chen, Chuan-Mu Min, Ming-Yuan Yang, Hsiu-Wen J Biomed Sci Research BACKGROUND: The descending noradrenergic (NAergic) system is one of the important endogenous analgesia systems. It has been suggested that noxious stimuli could activate descending NAergic system; nevertheless, the underlying neuronal circuit remains unclear. As NAergic neurons in the A7 catecholamine cell group (A7) are a part of the descending NAergic system and the lateral parabrachial nucleus (LPB) is an important brainstem structure that relays ascending nociceptive signal, we aimed to test whether LPB neurons have direct synaptic contact with NAergic A7 neurons. RESULTS: Stereotaxic injections of an anterograde tracer, biotinylated dextran-amine (BDA), were administered to LPB in rats. The BDA-labeled axonal terminals that have physical contacts with tyrosine hydroxylase-positive (presumed noadrenergic) neurons were identified in A7. Consistent with these morphological observations, the excitatory synaptic currents (EPSCs) were readily evoked in NAergic A7 neurons by extracellular stimulation of LPB. The EPSCs evoked by LPB stimulation were blocked by CNQX, a non-NMDA receptor blocker, and AP5, a selective NMDA receptor blocker, showing that LPB-A7 synaptic transmission is glutamatergic. Moreover, the amplitude of LPB-A7 EPSCs was significantly attenuated by DAMGO, a selective μ-opioid receptor agonist, which was associated with an increase in paired-pulse ratio. CONCLUSIONS: Taken together, the above results showed direct synaptic connections between LPB and A7 catecholamine cell group, the function of which is subject to presynaptic modulation by μ-opioid receptors. BioMed Central 2015-09-18 /pmc/articles/PMC4575445/ /pubmed/26385355 http://dx.doi.org/10.1186/s12929-015-0179-2 Text en © Liu et al. 2015 Open AccessThis article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated.
spellingShingle Research
Liu, Chia-Yi
Lee, Meng-Lam
Yang, Chi-Sheng
Chen, Chuan-Mu
Min, Ming-Yuan
Yang, Hsiu-Wen
Morphological and physiological evidence of a synaptic connection between the lateral parabrachial nucleus and neurons in the A7 catecholamine cell group in rats
title Morphological and physiological evidence of a synaptic connection between the lateral parabrachial nucleus and neurons in the A7 catecholamine cell group in rats
title_full Morphological and physiological evidence of a synaptic connection between the lateral parabrachial nucleus and neurons in the A7 catecholamine cell group in rats
title_fullStr Morphological and physiological evidence of a synaptic connection between the lateral parabrachial nucleus and neurons in the A7 catecholamine cell group in rats
title_full_unstemmed Morphological and physiological evidence of a synaptic connection between the lateral parabrachial nucleus and neurons in the A7 catecholamine cell group in rats
title_short Morphological and physiological evidence of a synaptic connection between the lateral parabrachial nucleus and neurons in the A7 catecholamine cell group in rats
title_sort morphological and physiological evidence of a synaptic connection between the lateral parabrachial nucleus and neurons in the a7 catecholamine cell group in rats
topic Research
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4575445/
https://www.ncbi.nlm.nih.gov/pubmed/26385355
http://dx.doi.org/10.1186/s12929-015-0179-2
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