Hypothesis for novel classes of chemoreceptors mediating chemogenic pain and itch

LaMotte, R. H.; Simone, Donald A.; Baumann, Thomas; Shain, C. N.; Alreja, Meenakshi

doi:10.1016/0304-3959(87)91109-2

Cited by 24 publications

(16 citation statements)

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“…LaMotte and co-workers (LaMotte, Simone, Baumann, Shain & Alreja, 1988;LaMotte et al 1991) have postulated the existence of a novel class of chemonociceptors in humans which could be particularly powerful in mediating secondary hyperalgesia to various forms of mechanical stimuli applied to a region surrounding a tissue injury. A particular feature of at least some of these nociceptors would be their widespread branches in the skin.…”

Section: Discussionmentioning

confidence: 99%

Sensitization of insensitive branches of C nociceptors in human skin.

Schmelz

Schmidt

Ringkamp

et al. 1994

The Journal of Physiology

116

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Section: Discussionmentioning

confidence: 99%

Sensitization of insensitive branches of C nociceptors in human skin.

Schmelz

Schmidt

Ringkamp

et al. 1994

The Journal of Physiology

116

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“…Evidence from studies in both humans and monkeys indicate that intradermal injection of capsaicin stimulates c-polymodal afferents much less vigorously than does more superficial administration, yet intense burning sensations can result from both modes of application (Simone, Ngeow, Whitehouse, et al, 1987). The latter observation leaves open the possibility that one or more cutaneous chemoreceptors exist that have not yet been identified (see Lamotte, Simone, Baumann, Shain, & Alreja, 1988;Meyer & Campbell, 1988).…”

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confidence: 99%

Spatial summation of chemical irritation and itch produced by topical application of capsaicin

Green

1990

Perception & Psychophysics

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The effect of increasing the total area of stimulation on the sensations of irritation produced by topical application of capsaicin was studied in two experiments. In the first experiment, stimulus area was varied by changing the size of filter paper disks on which capsaicin was delivered to the skin of the forearm. Subjects rated the intensity and quality of the cutaneous sensations over a 15-min period. Increasing stimulus area by a factor of 15 resulted in a relatively modest increase in the peak perceived intensity of irritation, a shortening of the latency to the onset of irritation, and shifts in the frequency of reports of sensations of itching and stinging/pricking. However, itch was the most frequently reported sensation regardless of stimulus size. In Experiment 2, stimulus area was manipulated by varying the number of stimuli applied to the skin. Despite a smaller difference in total stimulus areas (9-fold vs. 15-fold),the difference in perceived irritation was more pronounced than it was in Experiment 1 and reached statistical significance. It is therefore concluded that spatial summation does occur in the afferent system or systems responsible for the perception of capsaicin on the skin. This result is consistent with previous reports of summation at the threshold for heat pain and constitutes new information about the spatial integration of pruritic stimulation.Spatial summation is a common property of the cutaneous senses. Enlarging the area of stimulation has been shown to increase the sensitivity of the skin to vibration

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“…It has been proven that most experimental itch stimuli act via histamine release from mast cells, and that application of different concentrations of histamine into the skin causes different degrees of itching (Handwerker et al, 1987;Simone et al, 1987;Magerl et al, 1990). From these observations nerve fibers sensitive to histamine have been postulated (LaMotte et al, 1988;LaMotte, 1992). These presumed "itch units" are probably unmyelinated, because differential blocking of the myelinated fibers in skin nerves does not abolish histamineinduced itching (Handwerker et al, 1987).…”

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Specific C-Receptors for Itch in Human Skin

et al. 1997

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In microneurography experiments 56 unmyelinated nerve fibers were studied in the cutaneous branch of the peroneal nerve of healthy volunteers. Units were identified with the "marking" technique as mechanically and heat-responsive (CMH; n ϭ 30), heat-responsive (CH; n ϭ 13), or unresponsive to mechanical and heat stimulation (CM i H i ; n ϭ 13). None of the units showed spontaneous activity.These units were tested for responsiveness to iontophoresis of histamine (1 mA, 20 sec) from a small probe (diameter, 6 mm), which induced itch sensations lasting several minutes. Twenty-three units were unresponsive to histamine, and 25 units responded weakly with a few spike discharges after iontophoresis.Eight units, however, responded with sustained discharges to histamine, and their discharge patterns were matching the time course of the itch sensations. All C-units in this group were mechanically insensitive, and five of them were heat-responsive. They had very low conduction velocities of only 0.5 m/sec, on average, which is significantly lower than conduction velocities of the "polymodal" CMH units. This slow conduction velocities attributable to small axon diameters may be one reason why these units have not been encountered in previous studies. Histaminesensitive C-units had very large innervation territories extending up to a diameter of 85 mm on the lower leg.We conclude that these C-fibers represent a new class of afferent nerve fibers with particularly thin axons but excessive terminal branching. This type of C-fiber probably represents the afferent units long searched for mediating itch sensations.

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Hypothesis for novel classes of chemoreceptors mediating chemogenic pain and itch

Cited by 24 publications

References 0 publications

Sensitization of insensitive branches of C nociceptors in human skin.

Sensitization of insensitive branches of C nociceptors in human skin.

Spatial summation of chemical irritation and itch produced by topical application of capsaicin

Specific C-Receptors for Itch in Human Skin

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