Divya Tumbala Gutti, Richard Carr, Martin Schmelz, Roman Rukwied
{"title":"缓慢的去极化电刺激揭示了人体皮肤局部长时间使用辣椒素后痛觉感受器恢复的不同时间过程","authors":"Divya Tumbala Gutti, Richard Carr, Martin Schmelz, Roman Rukwied","doi":"10.1002/ejp.4726","DOIUrl":null,"url":null,"abstract":"BackgroundWe examined de‐functionalization and temporal functional recovery of C‐nociceptor evoked pain after topical 8% capsaicin applied for 4 consecutive days.MethodsCapsaicin and placebo patches were applied to human forearm skin (<jats:italic>n</jats:italic> = 14). Cold, warmth and heat pain thresholds, pain NRS to electrical and thermal (48°C, 5 s) stimuli and axon reflex flare were recorded weekly for 49 days. Mechanical and heat sensitive (‘polymodal’) nociceptors were activated by single electrical half‐period sinusoidal pulses (0.5 s, 1 Hz). Mechanical and heat <jats:italic>in</jats:italic>sensitive (‘silent’) nociceptors were activated by 4 Hz sinusoidal stimuli.ResultsCapsaicin abolished heat pain. Sensation to electrical sinusoidal stimulation was reduced but never abolished during the treatment. Pain to electrical 1 Hz ‘polymodal’ nociceptor stimulation took longer to recover than pain ratings to 4 Hz 2.5 s sinusoidal stimulation activating ‘polymodal’ and ‘silent’ nociceptors (35 vs. 21 days). Heat pain was indifferent to placebo from day 21–49. Axon reflex flare was abolished during capsaicin and only recovered to ~50% even after 49 days.ConclusionsCapsaicin abolishes heat transduction at terminal nociceptive endings, whereas small‐diameter axons sensitive to sinusoidal electrical stimulation can still be activated. 1 Hz depolarizing stimuli evoke burst discharges, as demonstrated before, and recover slower after capsaicin than single pulses induced by 4 Hz. The difference in recovery suggests differential time course of functional regeneration for C‐nociceptor sub‐types after capsaicin. All sensations recovered completely within 7 weeks in healthy subjects. Our findings contrast analgesia lasting for months in spontaneous neuropathic pain patients treated with 8% capsaicin.SignificanceSinusoidal electrical stimulation can still activate small diameter axons desensitized to heat after 4 consecutive days of topical 8% capsaicin application and reveals differential temporal functional regeneration of C‐nociceptor sub‐types. Electrical sinusoidal stimulation may detect such axons that no longer respond to heat stimuli in neuropathic skin.","PeriodicalId":12021,"journal":{"name":"European Journal of Pain","volume":null,"pages":null},"PeriodicalIF":3.5000,"publicationDate":"2024-09-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"Slow depolarizing electrical stimuli reveal differential time courses of nociceptor recovery after prolonged topical capsaicin in human skin\",\"authors\":\"Divya Tumbala Gutti, Richard Carr, Martin Schmelz, Roman Rukwied\",\"doi\":\"10.1002/ejp.4726\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"BackgroundWe examined de‐functionalization and temporal functional recovery of C‐nociceptor evoked pain after topical 8% capsaicin applied for 4 consecutive days.MethodsCapsaicin and placebo patches were applied to human forearm skin (<jats:italic>n</jats:italic> = 14). Cold, warmth and heat pain thresholds, pain NRS to electrical and thermal (48°C, 5 s) stimuli and axon reflex flare were recorded weekly for 49 days. Mechanical and heat sensitive (‘polymodal’) nociceptors were activated by single electrical half‐period sinusoidal pulses (0.5 s, 1 Hz). Mechanical and heat <jats:italic>in</jats:italic>sensitive (‘silent’) nociceptors were activated by 4 Hz sinusoidal stimuli.ResultsCapsaicin abolished heat pain. Sensation to electrical sinusoidal stimulation was reduced but never abolished during the treatment. Pain to electrical 1 Hz ‘polymodal’ nociceptor stimulation took longer to recover than pain ratings to 4 Hz 2.5 s sinusoidal stimulation activating ‘polymodal’ and ‘silent’ nociceptors (35 vs. 21 days). Heat pain was indifferent to placebo from day 21–49. Axon reflex flare was abolished during capsaicin and only recovered to ~50% even after 49 days.ConclusionsCapsaicin abolishes heat transduction at terminal nociceptive endings, whereas small‐diameter axons sensitive to sinusoidal electrical stimulation can still be activated. 1 Hz depolarizing stimuli evoke burst discharges, as demonstrated before, and recover slower after capsaicin than single pulses induced by 4 Hz. The difference in recovery suggests differential time course of functional regeneration for C‐nociceptor sub‐types after capsaicin. All sensations recovered completely within 7 weeks in healthy subjects. Our findings contrast analgesia lasting for months in spontaneous neuropathic pain patients treated with 8% capsaicin.SignificanceSinusoidal electrical stimulation can still activate small diameter axons desensitized to heat after 4 consecutive days of topical 8% capsaicin application and reveals differential temporal functional regeneration of C‐nociceptor sub‐types. Electrical sinusoidal stimulation may detect such axons that no longer respond to heat stimuli in neuropathic skin.\",\"PeriodicalId\":12021,\"journal\":{\"name\":\"European Journal of Pain\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":3.5000,\"publicationDate\":\"2024-09-19\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"European Journal of Pain\",\"FirstCategoryId\":\"3\",\"ListUrlMain\":\"https://doi.org/10.1002/ejp.4726\",\"RegionNum\":2,\"RegionCategory\":\"医学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"ANESTHESIOLOGY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"European Journal of Pain","FirstCategoryId":"3","ListUrlMain":"https://doi.org/10.1002/ejp.4726","RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ANESTHESIOLOGY","Score":null,"Total":0}
Slow depolarizing electrical stimuli reveal differential time courses of nociceptor recovery after prolonged topical capsaicin in human skin
BackgroundWe examined de‐functionalization and temporal functional recovery of C‐nociceptor evoked pain after topical 8% capsaicin applied for 4 consecutive days.MethodsCapsaicin and placebo patches were applied to human forearm skin (n = 14). Cold, warmth and heat pain thresholds, pain NRS to electrical and thermal (48°C, 5 s) stimuli and axon reflex flare were recorded weekly for 49 days. Mechanical and heat sensitive (‘polymodal’) nociceptors were activated by single electrical half‐period sinusoidal pulses (0.5 s, 1 Hz). Mechanical and heat insensitive (‘silent’) nociceptors were activated by 4 Hz sinusoidal stimuli.ResultsCapsaicin abolished heat pain. Sensation to electrical sinusoidal stimulation was reduced but never abolished during the treatment. Pain to electrical 1 Hz ‘polymodal’ nociceptor stimulation took longer to recover than pain ratings to 4 Hz 2.5 s sinusoidal stimulation activating ‘polymodal’ and ‘silent’ nociceptors (35 vs. 21 days). Heat pain was indifferent to placebo from day 21–49. Axon reflex flare was abolished during capsaicin and only recovered to ~50% even after 49 days.ConclusionsCapsaicin abolishes heat transduction at terminal nociceptive endings, whereas small‐diameter axons sensitive to sinusoidal electrical stimulation can still be activated. 1 Hz depolarizing stimuli evoke burst discharges, as demonstrated before, and recover slower after capsaicin than single pulses induced by 4 Hz. The difference in recovery suggests differential time course of functional regeneration for C‐nociceptor sub‐types after capsaicin. All sensations recovered completely within 7 weeks in healthy subjects. Our findings contrast analgesia lasting for months in spontaneous neuropathic pain patients treated with 8% capsaicin.SignificanceSinusoidal electrical stimulation can still activate small diameter axons desensitized to heat after 4 consecutive days of topical 8% capsaicin application and reveals differential temporal functional regeneration of C‐nociceptor sub‐types. Electrical sinusoidal stimulation may detect such axons that no longer respond to heat stimuli in neuropathic skin.
期刊介绍:
European Journal of Pain (EJP) publishes clinical and basic science research papers relevant to all aspects of pain and its management, including specialties such as anaesthesia, dentistry, neurology and neurosurgery, orthopaedics, palliative care, pharmacology, physiology, psychiatry, psychology and rehabilitation; socio-economic aspects of pain are also covered.
Regular sections in the journal are as follows:
• Editorials and Commentaries
• Position Papers and Guidelines
• Reviews
• Original Articles
• Letters
• Bookshelf
The journal particularly welcomes clinical trials, which are published on an occasional basis.
Research articles are published under the following subject headings:
• Neurobiology
• Neurology
• Experimental Pharmacology
• Clinical Pharmacology
• Psychology
• Behavioural Therapy
• Epidemiology
• Cancer Pain
• Acute Pain
• Clinical Trials.