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Increasing Pain Sensation Eliminates the Inhibitory Effect of Depression on Evoked Pain in Rats

Although previous studies have suggested that depression may be associated with inhibition of evoked pain but facilitation of spontaneous pain, the mechanisms underlying these relationships are unclear. The present study investigated whether the difference between evoked and spontaneous pain on sens...

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Autores principales: Wang, Ning, Li, Sheng-Guang, Lin, Xiao-Xiao, Su, Yuan-Lin, Qi, Wei-Jing, Wang, Jin-Yan, Luo, Fei
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Frontiers Media S.A. 2016
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5039174/
https://www.ncbi.nlm.nih.gov/pubmed/27733820
http://dx.doi.org/10.3389/fnbeh.2016.00183
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author Wang, Ning
Li, Sheng-Guang
Lin, Xiao-Xiao
Su, Yuan-Lin
Qi, Wei-Jing
Wang, Jin-Yan
Luo, Fei
author_facet Wang, Ning
Li, Sheng-Guang
Lin, Xiao-Xiao
Su, Yuan-Lin
Qi, Wei-Jing
Wang, Jin-Yan
Luo, Fei
author_sort Wang, Ning
collection PubMed
description Although previous studies have suggested that depression may be associated with inhibition of evoked pain but facilitation of spontaneous pain, the mechanisms underlying these relationships are unclear. The present study investigated whether the difference between evoked and spontaneous pain on sensory (descending inhibition) and affective (avoidance motivation) components contributes to the divergent effects of depression on them. Depressive-like behavior was produced in male Wistar rats by unpredictable chronic mild stress (UCMS). Tone-laser conditioning and formalin-induced conditioned place avoidance (F-CPA) were used to explore avoidance motivation in evoked and spontaneous pain, respectively. Behavioral pharmacology experiments were conducted to examine descending inhibition of both evoked (thermal stimulation) and spontaneous pain behavior (formalin pain). The results revealed that the inhibitory effect of depression on evoked pain was eliminated following repeated thermal stimuli. Avoidance behavior in the tone-laser conditioning task was reduced in UCMS rats, relative to controls. However, avoidance motivation for formalin pain in the UCMS group was similar to controls. 5-HT(1A) receptor antagonism interfered with inhibition of pain responses over time. The present study demonstrated that the inhibitory effect of depression on evoked pain dissipates with increased nociception and that the sensory-discriminative and affective-motivational components of pain are jointly involved in the divergent effects of depression on pain.
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spelling pubmed-50391742016-10-12 Increasing Pain Sensation Eliminates the Inhibitory Effect of Depression on Evoked Pain in Rats Wang, Ning Li, Sheng-Guang Lin, Xiao-Xiao Su, Yuan-Lin Qi, Wei-Jing Wang, Jin-Yan Luo, Fei Front Behav Neurosci Neuroscience Although previous studies have suggested that depression may be associated with inhibition of evoked pain but facilitation of spontaneous pain, the mechanisms underlying these relationships are unclear. The present study investigated whether the difference between evoked and spontaneous pain on sensory (descending inhibition) and affective (avoidance motivation) components contributes to the divergent effects of depression on them. Depressive-like behavior was produced in male Wistar rats by unpredictable chronic mild stress (UCMS). Tone-laser conditioning and formalin-induced conditioned place avoidance (F-CPA) were used to explore avoidance motivation in evoked and spontaneous pain, respectively. Behavioral pharmacology experiments were conducted to examine descending inhibition of both evoked (thermal stimulation) and spontaneous pain behavior (formalin pain). The results revealed that the inhibitory effect of depression on evoked pain was eliminated following repeated thermal stimuli. Avoidance behavior in the tone-laser conditioning task was reduced in UCMS rats, relative to controls. However, avoidance motivation for formalin pain in the UCMS group was similar to controls. 5-HT(1A) receptor antagonism interfered with inhibition of pain responses over time. The present study demonstrated that the inhibitory effect of depression on evoked pain dissipates with increased nociception and that the sensory-discriminative and affective-motivational components of pain are jointly involved in the divergent effects of depression on pain. Frontiers Media S.A. 2016-09-28 /pmc/articles/PMC5039174/ /pubmed/27733820 http://dx.doi.org/10.3389/fnbeh.2016.00183 Text en Copyright © 2016 Wang, Li, Lin, Su, Qi, Wang and Luo. http://creativecommons.org/licenses/by/4.0/ This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution and reproduction in other forums is permitted, provided the original author(s) or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
spellingShingle Neuroscience
Wang, Ning
Li, Sheng-Guang
Lin, Xiao-Xiao
Su, Yuan-Lin
Qi, Wei-Jing
Wang, Jin-Yan
Luo, Fei
Increasing Pain Sensation Eliminates the Inhibitory Effect of Depression on Evoked Pain in Rats
title Increasing Pain Sensation Eliminates the Inhibitory Effect of Depression on Evoked Pain in Rats
title_full Increasing Pain Sensation Eliminates the Inhibitory Effect of Depression on Evoked Pain in Rats
title_fullStr Increasing Pain Sensation Eliminates the Inhibitory Effect of Depression on Evoked Pain in Rats
title_full_unstemmed Increasing Pain Sensation Eliminates the Inhibitory Effect of Depression on Evoked Pain in Rats
title_short Increasing Pain Sensation Eliminates the Inhibitory Effect of Depression on Evoked Pain in Rats
title_sort increasing pain sensation eliminates the inhibitory effect of depression on evoked pain in rats
topic Neuroscience
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5039174/
https://www.ncbi.nlm.nih.gov/pubmed/27733820
http://dx.doi.org/10.3389/fnbeh.2016.00183
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