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Mechanical sensitization, increased axonal excitability, and spontaneous activity in C-nociceptors after ultraviolet B irradiation in pig skin.
Pain. 2021 07 01; 162(7):2002-2013.PAIN

Abstract

ABSTRACT

Ultraviolet B (UVB) irradiation induces hyperalgesia in human and animal pain models. We investigated mechanical sensitization, increase in axonal excitability, and spontaneous activity in different C-nociceptor classes after UVB in pig skin. We focused on units with receptive fields covering both irradiated and nonirradiated skin allowing intraindividual comparisons. Thirty-five pigs were irradiated in a chessboard pattern, and extracellular single-fibre recordings were obtained 10 to 28 hours later (152 fibers). Units from the contralateral hind limb served as a control (n = 112). Irradiated and nonirradiated parts of the same innervation territory were compared in 36 neurons; low threshold C-touch fibers (n = 10) and sympathetic efferents (n = 2) were unchanged, but lower mechanical thresholds and higher discharge frequency at threshold were found in mechanosensitive nociceptors (n = 12). Half of them could be activated with nonnoxious brush stimuli in the sunburn. Four of 12 mechanoinsensitive nociceptors were found sensitized to mechanical stimulation in the irradiated part of the receptive field. Activity-dependent slowing of conduction was reduced in the irradiated and in the nonirradiated skin as compared with the control leg, whereas increased ability to follow high stimulation frequencies was restricted to the sunburn (108.5 ± 37 Hz UVB vs 6.3 ± 1 Hz control). Spontaneous activity was more frequent in the sunburn (72/152 vs 31/112). Mechanical sensitization of primary nociceptors and higher maximum after frequency are suggested to contribute to primary hyperalgesia, whereas the spontaneous activity of silent nociceptors might offer a mechanistic link contributing to ongoing pain and facilitated induction of spinal sensitization.

Authors+Show Affiliations

Department of Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.Department of Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.Department of Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.Department of Mathematics and Computer Science, Bethel University, Saint Paul, MI, United States. Dr. Obreja is now with the Klinik für Rheumatologie und Schmerzmedizin, Bethesda Spital Basel, Basel, Switzerland.Department of Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.Department of Experimental Pain Research, MCTN, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany.

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

33449511

Citation

Werland, Fiona, et al. "Mechanical Sensitization, Increased Axonal Excitability, and Spontaneous Activity in C-nociceptors After Ultraviolet B Irradiation in Pig Skin." Pain, vol. 162, no. 7, 2021, pp. 2002-2013.
Werland F, de Col R, Hirth M, et al. Mechanical sensitization, increased axonal excitability, and spontaneous activity in C-nociceptors after ultraviolet B irradiation in pig skin. Pain. 2021;162(7):2002-2013.
Werland, F., de Col, R., Hirth, M., Turnquist, B., Schmelz, M., & Obreja, O. (2021). Mechanical sensitization, increased axonal excitability, and spontaneous activity in C-nociceptors after ultraviolet B irradiation in pig skin. Pain, 162(7), 2002-2013. https://doi.org/10.1097/j.pain.0000000000002197
Werland F, et al. Mechanical Sensitization, Increased Axonal Excitability, and Spontaneous Activity in C-nociceptors After Ultraviolet B Irradiation in Pig Skin. Pain. 2021 07 1;162(7):2002-2013. PubMed PMID: 33449511.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Mechanical sensitization, increased axonal excitability, and spontaneous activity in C-nociceptors after ultraviolet B irradiation in pig skin. AU - Werland,Fiona, AU - de Col,Roberto, AU - Hirth,Michael, AU - Turnquist,Brian, AU - Schmelz,Martin, AU - Obreja,Otilia, PY - 2020/10/12/received PY - 2020/12/30/accepted PY - 2021/1/16/pubmed PY - 2021/6/25/medline PY - 2021/1/15/entrez SP - 2002 EP - 2013 JF - Pain JO - Pain VL - 162 IS - 7 N2 - ABSTRACT: Ultraviolet B (UVB) irradiation induces hyperalgesia in human and animal pain models. We investigated mechanical sensitization, increase in axonal excitability, and spontaneous activity in different C-nociceptor classes after UVB in pig skin. We focused on units with receptive fields covering both irradiated and nonirradiated skin allowing intraindividual comparisons. Thirty-five pigs were irradiated in a chessboard pattern, and extracellular single-fibre recordings were obtained 10 to 28 hours later (152 fibers). Units from the contralateral hind limb served as a control (n = 112). Irradiated and nonirradiated parts of the same innervation territory were compared in 36 neurons; low threshold C-touch fibers (n = 10) and sympathetic efferents (n = 2) were unchanged, but lower mechanical thresholds and higher discharge frequency at threshold were found in mechanosensitive nociceptors (n = 12). Half of them could be activated with nonnoxious brush stimuli in the sunburn. Four of 12 mechanoinsensitive nociceptors were found sensitized to mechanical stimulation in the irradiated part of the receptive field. Activity-dependent slowing of conduction was reduced in the irradiated and in the nonirradiated skin as compared with the control leg, whereas increased ability to follow high stimulation frequencies was restricted to the sunburn (108.5 ± 37 Hz UVB vs 6.3 ± 1 Hz control). Spontaneous activity was more frequent in the sunburn (72/152 vs 31/112). Mechanical sensitization of primary nociceptors and higher maximum after frequency are suggested to contribute to primary hyperalgesia, whereas the spontaneous activity of silent nociceptors might offer a mechanistic link contributing to ongoing pain and facilitated induction of spinal sensitization. SN - 1872-6623 UR - https://www.unboundmedicine.com/medline/citation/33449511/Mechanical_sensitization_increased_axonal_excitability_and_spontaneous_activity_in_C_nociceptors_after_ultraviolet_B_irradiation_in_pig_skin_ L2 - https://doi.org/10.1097/j.pain.0000000000002197 DB - PRIME DP - Unbound Medicine ER -