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Dietary constituent, decanoic acid suppresses the excitability of nociceptive trigeminal neuronal activity associated with hypoalgesia via muscarinic M(2) receptor signaling

BACKGROUND: Although decanoic acid (DA) is thought to act as a muscarinic cholinergic agonist, effect of DA on nociceptive behavioral responses and the excitability of nociceptive neuronal activity under in vivo conditions remain to be determined. The aim of the present study, therefore, was to inve...

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Autores principales: Noguchi, Yuna, Matsuzawa, Nichiwa, Akama, Youichi, Sekiguchi, Kenta, Takehana, Shiori, Shimazu, Yoshihito, Takeda, Mamoru
Formato: Online Artículo Texto
Lenguaje:English
Publicado: SAGE Publications 2017
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5448867/
https://www.ncbi.nlm.nih.gov/pubmed/28474958
http://dx.doi.org/10.1177/1744806917710779
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author Noguchi, Yuna
Matsuzawa, Nichiwa
Akama, Youichi
Sekiguchi, Kenta
Takehana, Shiori
Shimazu, Yoshihito
Takeda, Mamoru
author_facet Noguchi, Yuna
Matsuzawa, Nichiwa
Akama, Youichi
Sekiguchi, Kenta
Takehana, Shiori
Shimazu, Yoshihito
Takeda, Mamoru
author_sort Noguchi, Yuna
collection PubMed
description BACKGROUND: Although decanoic acid (DA) is thought to act as a muscarinic cholinergic agonist, effect of DA on nociceptive behavioral responses and the excitability of nociceptive neuronal activity under in vivo conditions remain to be determined. The aim of the present study, therefore, was to investigate whether in vivo acute administration of ointment containing DA affects the excitability of nociceptive trigeminal spinal nucleus caudalis (SpVc) neurons associated with hypoalgesia in naïve rats. RESULTS: After local application of DA, the threshold of escape from mechanical stimulation applied to the shaved orofacial skin was significantly higher than before DA application. Vehicle treatment (without DA) had no significant effect on the escape threshold from mechanical stimulation. Extracellular single unit recordings were made from SpVc wide-dynamic range (WDR) neurons in response to orofacial non-noxious and noxious mechanical stimuli of pentobarbital-anesthetized rats. The mean firing frequency of SpVc WDR neurons in response to noxious, but not non-noxious, mechanical stimuli was inhibited by local application of DA, and the maximum inhibition of discharge frequency of both non-noxious and noxious mechanical stimuli was seen within 1–5 min. The DA-induced short-term inhibitory effects were reversed after approximately 10 min. Pretreatment intravenously with the muscarinic-specific M(2) receptor antagonist, methoctramine, abolished the DA-induced suppression of firing frequency of SpVc WDR neurons in response to noxious stimulation. Fluorogold (FG) labeling was identified as the trigeminal ganglion (TG) neurons innervating orofacial skin. FG-labeled small-diameter TG neurons expressed M(2) receptor immunoreactivity. CONCLUSION: These results suggest that acute DA application induces short-term mechanical hypoalgesia and this effect was mainly due to suppression of the excitability of SpVc WDR neurons via the peripheral M(2) receptor signaling pathway in the trigeminal primary afferents. These findings support the idea that DA is a potential therapeutic agent and complementary alternative medicine for the attenuation of trigeminal nociception in the absence of inflammatory/neuropathic conditions.
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spelling pubmed-54488672017-06-08 Dietary constituent, decanoic acid suppresses the excitability of nociceptive trigeminal neuronal activity associated with hypoalgesia via muscarinic M(2) receptor signaling Noguchi, Yuna Matsuzawa, Nichiwa Akama, Youichi Sekiguchi, Kenta Takehana, Shiori Shimazu, Yoshihito Takeda, Mamoru Mol Pain Research Article BACKGROUND: Although decanoic acid (DA) is thought to act as a muscarinic cholinergic agonist, effect of DA on nociceptive behavioral responses and the excitability of nociceptive neuronal activity under in vivo conditions remain to be determined. The aim of the present study, therefore, was to investigate whether in vivo acute administration of ointment containing DA affects the excitability of nociceptive trigeminal spinal nucleus caudalis (SpVc) neurons associated with hypoalgesia in naïve rats. RESULTS: After local application of DA, the threshold of escape from mechanical stimulation applied to the shaved orofacial skin was significantly higher than before DA application. Vehicle treatment (without DA) had no significant effect on the escape threshold from mechanical stimulation. Extracellular single unit recordings were made from SpVc wide-dynamic range (WDR) neurons in response to orofacial non-noxious and noxious mechanical stimuli of pentobarbital-anesthetized rats. The mean firing frequency of SpVc WDR neurons in response to noxious, but not non-noxious, mechanical stimuli was inhibited by local application of DA, and the maximum inhibition of discharge frequency of both non-noxious and noxious mechanical stimuli was seen within 1–5 min. The DA-induced short-term inhibitory effects were reversed after approximately 10 min. Pretreatment intravenously with the muscarinic-specific M(2) receptor antagonist, methoctramine, abolished the DA-induced suppression of firing frequency of SpVc WDR neurons in response to noxious stimulation. Fluorogold (FG) labeling was identified as the trigeminal ganglion (TG) neurons innervating orofacial skin. FG-labeled small-diameter TG neurons expressed M(2) receptor immunoreactivity. CONCLUSION: These results suggest that acute DA application induces short-term mechanical hypoalgesia and this effect was mainly due to suppression of the excitability of SpVc WDR neurons via the peripheral M(2) receptor signaling pathway in the trigeminal primary afferents. These findings support the idea that DA is a potential therapeutic agent and complementary alternative medicine for the attenuation of trigeminal nociception in the absence of inflammatory/neuropathic conditions. SAGE Publications 2017-05-05 /pmc/articles/PMC5448867/ /pubmed/28474958 http://dx.doi.org/10.1177/1744806917710779 Text en © The Author(s) 2017 http://creativecommons.org/licenses/by-nc/4.0/ This article is distributed under the terms of the Creative Commons Attribution-NonCommercial 4.0 License (http://www.creativecommons.org/licenses/by-nc/4.0/) which permits non-commercial use, reproduction and distribution of the work without further permission provided the original work is attributed as specified on the SAGE and Open Access pages (https://us.sagepub.com/en-us/nam/open-access-at-sage).
spellingShingle Research Article
Noguchi, Yuna
Matsuzawa, Nichiwa
Akama, Youichi
Sekiguchi, Kenta
Takehana, Shiori
Shimazu, Yoshihito
Takeda, Mamoru
Dietary constituent, decanoic acid suppresses the excitability of nociceptive trigeminal neuronal activity associated with hypoalgesia via muscarinic M(2) receptor signaling
title Dietary constituent, decanoic acid suppresses the excitability of nociceptive trigeminal neuronal activity associated with hypoalgesia via muscarinic M(2) receptor signaling
title_full Dietary constituent, decanoic acid suppresses the excitability of nociceptive trigeminal neuronal activity associated with hypoalgesia via muscarinic M(2) receptor signaling
title_fullStr Dietary constituent, decanoic acid suppresses the excitability of nociceptive trigeminal neuronal activity associated with hypoalgesia via muscarinic M(2) receptor signaling
title_full_unstemmed Dietary constituent, decanoic acid suppresses the excitability of nociceptive trigeminal neuronal activity associated with hypoalgesia via muscarinic M(2) receptor signaling
title_short Dietary constituent, decanoic acid suppresses the excitability of nociceptive trigeminal neuronal activity associated with hypoalgesia via muscarinic M(2) receptor signaling
title_sort dietary constituent, decanoic acid suppresses the excitability of nociceptive trigeminal neuronal activity associated with hypoalgesia via muscarinic m(2) receptor signaling
topic Research Article
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5448867/
https://www.ncbi.nlm.nih.gov/pubmed/28474958
http://dx.doi.org/10.1177/1744806917710779
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