A multi-scale view of skin thermal pain: from nociception to pain sensation

Abstract

All biological bodies live in a thermal environment, including the human body, where skin is the interface with a protecting function. When the temperature is out of the normal physiological range, skin fails to protect, and the pain sensation is evoked. Furthermore, in medicine, with advances in laser, microwave and similar technologies, various thermal therapeutic methods have been widely used to cure disease/injury involving skin tissue. However, the corresponding problem of pain relief has limited further application and development of these thermal treatments. Skin thermal pain is induced through both direct (i.e. an increase/decrease in temperature) and indirect (e.g. thermomechanical and thermochemical) ways, and is governed by complicated thermomechanical-chemicalneurophysiological responses. However, a complete understanding of the underlying mechanisms is still far from clear. In this article, starting from an engineering perspective, we aim to recast the biological behaviour of skin in engineering system parlance. Then, by coupling the concepts of engineering with established methods in neuroscience, we attempt to establish multi-scale modelling of skin thermal pain through ion channel to pain sensation. The model takes into account skin morphological plausibility, the thermomechanical response of skin tissue and the biophysical and neurological mechanisms of pain sensation.

Exploring the Mechanisms of Exercise-Induced Hypoalgesia Using Somatosensory and Laser Evoked Potentials

“…The activation of nociceptors by heat from a laser requires energy transmission to the receptor followed by transduction of this energy and action potential generation (Treede et al, 1995). A-delta fibers respond within approximately 40–100 ms of the rapid application of heat energy, depending on the stimulus intensity and the proximity of the laser beam to the receptive field of the nociceptor (Xu et al, 2008; Zhu and Lu, 2010). Thus, the approximately 230-ms onset latency of the N2P2 component of the LEP was consistent with the combination of the stimulus transduction time and the conduction velocity of A-delta fibers.…”

Purinergic Signaling in Healthy and Diseased Skin

“…Reviews concerning purinergic signaling and pain are available (Hamilton and McMahon, 2000;Burnstock, 2006Burnstock, , 2009bNakatsuka and Gu, 2008;Dussor et al, 2009;Zhu and Lu, 2010).…”

Dynamic and Permissive Roles of TRPV1 and TRPV4 Channels for Thermosensation in Mouse Supraoptic Magnocellular Neurosecretory Neurons

“…Finally, previous work has shown that supraoptic neurons do not express the full-length protein encoded by the trpv1 gene, but a variant lacking part of the channel's N-terminal cytoplasmic region (Sharif Naeini et al, 2006). Although it is the C-terminal region of the full-length TRPV1 protein that is required for thermosensation (Vlachová et al, 2003;Brauchi et al, 2006;Valente et al, 2008), it will be important to determine whether the variant expressed in supraoptic MNCs displays specific properties that somehow enhance its role as a thermosensory transducer.…”

“…In contrast to those located in the brain, which detect small deviations in temperature near Tb, thermosensory neurons located in the periphery must be capable of detecting and encoding an array of temperatures that ranges from nociceptive cooling (Ͻ15°C) to nociceptive heating (Ͼ40°C) (Foulkes and Wood, 2007;Zhu and Lu, 2010). Recent studies have suggested that this wide spectrum of sensitivity is achieved through the participation of distinct types of channels that are each sensitive to narrow yet overlapping ranges in temperature (Dhaka et al, 2006).…”