Faculty Opinions recommendation of Mechanical allodynia in human glabrous skin mediated by low-threshold cutaneous mechanoreceptors with unmyelinated fibres.

2013 ◽  
Author(s):  
Wilfrid Jänig
Keyword(s):  
Mechanical Allodynia ◽  
Glabrous Skin ◽  
Cutaneous Mechanoreceptors ◽  
Low Threshold

Mechanoreceptors in rat glabrous skin: redevelopment of function after nerve crush

1986 ◽  
Vol 55 (4) ◽  
pp. 644-659 ◽  
Author(s):  
K. H. Sanders ◽  
M. Zimmermann
Keyword(s):  
Normal Skin ◽  
Control Level ◽  
Underlying Mechanism ◽  
Nerve Fibers ◽  
Glabrous Skin ◽  
High Threshold ◽  
Cutaneous Mechanoreceptors ◽  
Nerve Crush ◽  
Low Threshold ◽  
Skin Indentation

In the glabrous skin of the rat's hindfoot the same triple set of low-threshold mechanoreceptors is present as has been found in other mammals: slowly adapting (SA), rapidly adapting (RA), and very rapidly adapting Pacinian corpuscle-like (PC) receptors. Their functional characteristics were examined in normal rats and compared with those of sensitive mechanoreceptors found in the glabrous skin of the foot 2-24 wk after crush of the plantar nerves, resulting in regeneration of the transected nerve fibers. After 2 wk of nerve regeneration, low-threshold RA and SA cutaneous mechanoreceptors reappeared in the foot skin. Responses of PC receptors were recorded again after 3 wk, at which time the proportion of fibers that could be identified as low-threshold cutaneous mechanoreceptors had regained control level. Discharge patterns of regenerated cutaneous mechanosensitive receptors were very similar to those of normal skin mechanoreceptors. Their sensitivity to controlled mechanical stimulation was, however, still reduced 4 wk after the lesion. After 8 wk RA and SA receptors had regained their normal dynamic sensitivity, i.e., the responsiveness to the velocity of skin indentation. The static sensitivity of SA receptors, i.e., responsiveness to maintained skin indentation, was not consistently reestablished within 24 wk. No shift in sensitivity could be deduced from tuning curves of PC receptors examined 3-24 wk after nerve crush. In addition to the low-threshold mechanoreceptors, high-threshold (HT) mechanoreceptive fibers were found in controls and in animals with regenerating nerves. This type of fiber was most frequently found 1 wk after the nerve crush, when reinnervation of the foot started. They probably represent fibers not connected to specific mechanoreceptor end organs. Thus, functional restitution of the highly specific cutaneous mechanoreceptors occurs fairly soon after invasion of the original territory by the regenerating nerve. It is assumed that the underlying mechanism is the rapid reconnection of fibers with the end organs that have either survived during the period of denervation or regenerated subsequent to reinnervation of the skin.

scholarly journals Low-threshold mechanoreceptors play a frequency-dependent dual role in subjective ratings of mechanical allodynia

2017 ◽  
Vol 118 (6) ◽  
pp. 3360-3369 ◽  
Author(s):  
Line S. Löken ◽  
Eugene P. Duff ◽  
Irene Tracey
Keyword(s):  
Mechanical Allodynia ◽  
Brain Activity ◽  
Normal Skin ◽  
Dual Role ◽  
Apparent Paradox ◽  
Frequency Dependent ◽  
Firing Rates ◽  
Dynamic Mechanical ◽  
Gate Control Theory ◽  
Low Threshold

In the setting of injury, myelinated primary afferent fibers that normally signal light touch are thought to switch modality and instead signal pain. In the absence of injury, touch is perceived as more intense when firing rates of Aβ afferents increase. However, it is not known if varying the firing rates of Aβ afferents have any consequence to the perception of dynamic mechanical allodynia (DMA). We hypothesized that, in the setting of injury, the unpleasantness of DMA would be intensified as the firing rates of Aβ afferents increase. Using a stimulus-response protocol established in normal skin, where an increase in brush velocity results in an increase of Aβ afferent firing rates, we tested if brush velocity modulated the unpleasantness of capsaicin-induced DMA. We analyzed how changes in estimated low-threshold mechanoreceptor firing activity influenced perception and brain activity (functional MRI) of DMA. Brushing on normal skin was perceived as pleasant, but brushing on sensitized skin produced both painful and pleasant sensations. Surprisingly, there was an inverse relationship between Aβ firing rates and unpleasantness such that brush stimuli that produced low firing rates were most painful and those that elicited high firing rates were rated as pleasant. Concurrently to this, we found increased cortical activity in response to low Aβ firing rates in regions previously implicated in pain processing during brushing of sensitized skin, but not normal skin. We suggest that Aβ signals do not merely switch modality to signal pain during injury. Instead, they exert a high- and low-frequency-dependent dual role in the injured state, with respectively both pleasant and unpleasant consequences. NEW & NOTEWORTHY We suggest that Aβ signals do not simply switch modality to signal pain during injury but play a frequency-dependent and dual role in the injured state with both pleasant and unpleasant consequences. These results provide a framework to resolve the apparent paradox of how touch can inhibit pain, as proposed by the Gate Control Theory and the existence of dynamic mechanical allodynia.

scholarly journals Interleukin-6 mediates low-threshold mechanical allodynia induced by intrathecal HIV-1 envelope glycoprotein gp120

2007 ◽  
Vol 21 (5) ◽  
pp. 660-667 ◽  
Author(s):  
Diana K. Schoeniger-Skinner ◽  
Annemarie Ledeboer ◽  
Matthew G. Frank ◽  
Erin D. Milligan ◽  
Stephen Poole ◽  
...  
Keyword(s):  
Interleukin 6 ◽  
Envelope Glycoprotein ◽  
Mechanical Allodynia ◽  
Envelope Glycoprotein Gp120 ◽  
Glycoprotein Gp120 ◽  
Low Threshold ◽  
Hiv 1

scholarly journals Sickle Cell Mice Exhibit Mechanical Allodynia and Enhanced Responsiveness in Light Touch Cutaneous Mechanoreceptors

2012 ◽  
Vol 8 ◽  
pp. 1744-8069-8-62 ◽  
Author(s):  
Sheldon R Garrison ◽  
Audra A Kramer ◽  
Nashaat Z Gerges ◽  
Cheryl A Hillery ◽  
Cheryl L Stucky
Keyword(s):  
Sickle Cell ◽  
Mechanical Allodynia ◽  
Light Touch ◽  
Cutaneous Mechanoreceptors

scholarly journals Tactile sensitivity in the rat: a correlation between receptor structure and function

2021 ◽  
Author(s):  
Lucia Guzun ◽  
Pascal Fortier-Poisson ◽  
Jean-Sébastien Langlais ◽  
Allan M. Smith
Keyword(s):  
Dermal Papilla ◽  
Glabrous Skin ◽  
Tactile Sensitivity ◽  
Pacinian Corpuscles ◽  
Cell Complexes ◽  
Anatomy And Physiology ◽  
Receptor Complexes ◽  
Receptor Structure ◽  
Low Threshold ◽  
And Function

AbstractSingle cutaneous fibers were recorded in the median nerve of the deeply anesthetized rat and the receptor morphology in the forelimb glabrous skin was analyzed to establish a probable correlation between receptor anatomy and physiology. Receptor complexes in the glabrous skin of the rat forelimb were stained immunologically with antibodies NF-200 and PGP-9.5, confirming the presence of Meissner corpuscles and Merkel complexes within the dermal papilla similar to other mammals including primates. Both the Meissner corpuscles and Merkel cell complexes were sparse and located in the pyramidal-shaped palmer pads and the apex of the digit extremities. They were almost totally absent elsewhere in the glabrous skin. No Ruffini receptors or Pacinian corpuscles were found in our samples. A total of 92 cutaneous fibers were retained long enough for analysis. Thirty-five (38%) were characterized as rapidly adapting fibers (RA) and 57 (62%) were slowly adapting afferents (SA). Despite the very limited number of receptors at the tip of the digit, RA receptors outnumbered SA fibers 3.2/1.0. In contrast, SA fibers on the thenar pad outnumbered RA receptors by a ratio of 3–1. Despite the very limited number of low threshold mechanoreceptors in the glabrous skin of the rat forelimb, the prevalence of SA afferents in the palm and more frequent occurrence of RA afferents in the digit extremity suggest differences in functionality both for locomotion and object manipulation.

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