Capsaicin-induced secondary hyperalgesia differences between the trigeminal and spinal innervation

Abstract This study compared the degree of secondary hyperalgesia and somatosensory threshold changes induced by topical capsaicin between spinal and trigeminal innervation. This crossover clinical trial included 40 healthy individuals in which 0.25 g of 1% capsaicin cream was randomly applied for 4...

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Main Authors: Isabela C. Novaes, Soraya S. Ardestani, Allen Matheus S. Nascimento, Paulo C. R. Conti, Leonardo R. Bonjardim, Peter Svensson, Fernando G. Exposto, Yuri M. Costa
Format: Article
Language:English
Published: Nature Portfolio 2025-01-01
Series:Scientific Reports
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Online Access:https://doi.org/10.1038/s41598-024-83312-8
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author Isabela C. Novaes
Soraya S. Ardestani
Allen Matheus S. Nascimento
Paulo C. R. Conti
Leonardo R. Bonjardim
Peter Svensson
Fernando G. Exposto
Yuri M. Costa
author_facet Isabela C. Novaes
Soraya S. Ardestani
Allen Matheus S. Nascimento
Paulo C. R. Conti
Leonardo R. Bonjardim
Peter Svensson
Fernando G. Exposto
Yuri M. Costa
author_sort Isabela C. Novaes
collection DOAJ
description Abstract This study compared the degree of secondary hyperalgesia and somatosensory threshold changes induced by topical capsaicin between spinal and trigeminal innervation. This crossover clinical trial included 40 healthy individuals in which 0.25 g of 1% capsaicin cream was randomly applied for 45 minutes to a circular area of 2 cm2 to the skin covering the masseter muscle and forearm in 2 different sessions, separated by at least 24 hours and no more than 72 hours (washout period). The main outcome variables were the area of allodynia and pinprick hyperalgesia, as well as electrical and mechanical pain thresholds within the area of pinprick hyperalgesia. Mixed ANOVA models and McNemar tests were applied to the data (p = 0.050). The occurrence of allodynia and pinprick hyperalgesia was higher in the forearm than in the masseter (p < 0.050). Additionally, the areas of pinprick hyperalgesia and allodynia were larger in the forearm compared to the masseter (p < 0.050). The electrical and mechanical pain thresholds demonstrated a loss of somatosensory function following capsaicin application to the masseter (p < 0.050). However, no significant somatosensory threshold changes were observed at the forearm after capsaicin (p > 0.050). In conclusion, these findings indicate potential differences compatible with central sensitization related to secondary hyperalgesia between trigeminal and spinal innervation.
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spelling doaj-art-02881bedc74b4333bbc5e459b10024c32025-01-05T12:18:55ZengNature PortfolioScientific Reports2045-23222025-01-0115111310.1038/s41598-024-83312-8Capsaicin-induced secondary hyperalgesia differences between the trigeminal and spinal innervationIsabela C. Novaes0Soraya S. Ardestani1Allen Matheus S. Nascimento2Paulo C. R. Conti3Leonardo R. Bonjardim4Peter Svensson5Fernando G. Exposto6Yuri M. Costa7Department of Biosciences, Universidade Estadual de Campinas (UNICAMP), Faculdade de Odontologia de Piracicaba (FOP)Department of Biosciences, Universidade Estadual de Campinas (UNICAMP), Faculdade de Odontologia de Piracicaba (FOP)Department of Biosciences, Universidade Estadual de Campinas (UNICAMP), Faculdade de Odontologia de Piracicaba (FOP)Department of Prosthetic Dentistry, Bauru School of Dentistry, University of Sao PauloSection of Head and Face Physiology, Department of Biological Sciences, Bauru School of Dentistry, University of Sao PauloFaculty of Dentistry, National University of SingaporeSection for Orofacial Pain and Jaw Function, Department of Dentistry and Oral Health, Aarhus UniversityDepartment of Biosciences, Universidade Estadual de Campinas (UNICAMP), Faculdade de Odontologia de Piracicaba (FOP)Abstract This study compared the degree of secondary hyperalgesia and somatosensory threshold changes induced by topical capsaicin between spinal and trigeminal innervation. This crossover clinical trial included 40 healthy individuals in which 0.25 g of 1% capsaicin cream was randomly applied for 45 minutes to a circular area of 2 cm2 to the skin covering the masseter muscle and forearm in 2 different sessions, separated by at least 24 hours and no more than 72 hours (washout period). The main outcome variables were the area of allodynia and pinprick hyperalgesia, as well as electrical and mechanical pain thresholds within the area of pinprick hyperalgesia. Mixed ANOVA models and McNemar tests were applied to the data (p = 0.050). The occurrence of allodynia and pinprick hyperalgesia was higher in the forearm than in the masseter (p < 0.050). Additionally, the areas of pinprick hyperalgesia and allodynia were larger in the forearm compared to the masseter (p < 0.050). The electrical and mechanical pain thresholds demonstrated a loss of somatosensory function following capsaicin application to the masseter (p < 0.050). However, no significant somatosensory threshold changes were observed at the forearm after capsaicin (p > 0.050). In conclusion, these findings indicate potential differences compatible with central sensitization related to secondary hyperalgesia between trigeminal and spinal innervation.https://doi.org/10.1038/s41598-024-83312-8CapsaicinCentral sensitizationSecondary hyperalgesiaOrofacial pain
spellingShingle Isabela C. Novaes
Soraya S. Ardestani
Allen Matheus S. Nascimento
Paulo C. R. Conti
Leonardo R. Bonjardim
Peter Svensson
Fernando G. Exposto
Yuri M. Costa
Capsaicin-induced secondary hyperalgesia differences between the trigeminal and spinal innervation
Scientific Reports
Capsaicin
Central sensitization
Secondary hyperalgesia
Orofacial pain
title Capsaicin-induced secondary hyperalgesia differences between the trigeminal and spinal innervation
title_full Capsaicin-induced secondary hyperalgesia differences between the trigeminal and spinal innervation
title_fullStr Capsaicin-induced secondary hyperalgesia differences between the trigeminal and spinal innervation
title_full_unstemmed Capsaicin-induced secondary hyperalgesia differences between the trigeminal and spinal innervation
title_short Capsaicin-induced secondary hyperalgesia differences between the trigeminal and spinal innervation
title_sort capsaicin induced secondary hyperalgesia differences between the trigeminal and spinal innervation
topic Capsaicin
Central sensitization
Secondary hyperalgesia
Orofacial pain
url https://doi.org/10.1038/s41598-024-83312-8
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