Cold fiber heat sensitivity: dependency of ‘paradoxical’ discharge on body temperature

Long, Randall R.

doi:10.1016/0006-8993(73)90110-8

Cited by 19 publications

(7 citation statements)

References 4 publications

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“…However, the possibility that LTN arises from classically defined cold fibers and warm fibers cannot be ruled out, as the thresholds of fibers that express TRPM8 and TRPV3 fall within the range of putative cold and warm fibers. Support for involvement of cold fibers comes from their 'paradoxical' response to high temperatures (Dodt and Zotterman 1952;Long 1973;Campero et al 2001) and from the phenomenon of the heat grill illusion, or 'synthetic heat' (Green 1977;Green 2002;Fruhstorfer et al 2003). Whereas the high threshold [>50°C; (Long 1977)] and temporal irregularity of the paradoxical discharge rule out a role for cold fibers in encoding heat pain, evidence that repeated heating sensitizes cold fibers to heat and lowered the threshold of the paradoxical discharge (Dubner et al 1975;Long 1977) led to speculation that cold fibers may contribute to heat hyperalgesia (Dubner et al 1975;Price and Dubner 1977).…”

Section: Discussionmentioning

confidence: 99%

Nociceptive sensations evoked from ‘spots’ in the skin by mild cooling and heating

Green

Roman

Schoen

et al. 2008

Pain

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It was recently found that nociceptive sensations (stinging, pricking, or burning) can be evoked by cooling or heating the skin to innocuous temperatures (e.g., 29°, 37°C). Here we show that this lowthreshold thermal nociception (LTN) can be traced to sensitive 'spots' in the skin equivalent to classically defined warm spots and cold spots. Because earlier work had shown that LTN is inhibited by simply touching a thermode to the skin, a spatial search procedure was devised that minimized tactile stimulation by sliding small thermodes (16 mm 2 and 1 mm 2 ) set to 28° or 36°C slowly across the lubricated skin of the forearm. The procedure uncovered three types of temperature-sensitive sites (thermal, bimodal and nociceptive) that contained one or more thermal, nociceptive or (rarely) bimodal spots. Repeated testing indicated that bimodal and nociceptive sites were less stable over time than thermal sites, and that mechanical contact differentially inhibited nociceptive sensations. Intensity ratings collected over a range of temperatures showed that LTN increased monotonically on heat-sensitive sites but not on cold-sensitive sites. These results provide psychophysical evidence that stimulation from primary afferent fibers with thresholds in the range of warm fibers and cold fibers is relayed to the pain pathway. However, the labile nature of LTN implies that these lowthreshold nociceptive inputs are subject to inhibitory controls. The implications of these findings for the roles of putative temperature receptors and nociceptors in innocuous thermoreception and thermal pain are discussed.

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Section: Discussionmentioning

confidence: 99%

Nociceptive sensations evoked from ‘spots’ in the skin by mild cooling and heating

Green

Roman

Schoen

et al. 2008

Pain

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“…Although cool cells are often inhibited by noxious heat (Fig. 3A, top), they are sometimes activated by noxious heat after a brief period of inhibition, often referred to as the "paradoxical" heat response (Long 1973(Long , 1977. Neurons recorded in dry eye animals were significantly more likely to be activated by noxious heat, which was defined as a positive Rmag value (P Ͻ 0.01, 2 analysis).…”

Section: Dry Eye Conditionmentioning

confidence: 99%

Dry eye modifies the thermal and menthol responses in rat corneal primary afferent cool cells

Kurose

Meng

2013

Journal of Neurophysiology

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Kurose M, Meng ID. Dry eye modifies the thermal and menthol responses in rat corneal primary afferent cool cells. J Neurophysiol 110: 495-504, 2013. First published May 1, 2013 doi:10.1152/jn.00222.2013.-Dry eye syndrome is a painful condition caused by inadequate or altered tear film on the ocular surface. Primary afferent cool cells innervating the cornea regulate the ocular fluid status by increasing reflex tearing in response to evaporative cooling and hyperosmicity. It has been proposed that activation of corneal cool cells via a transient receptor potential melastatin 8 (TRPM8) channel agonist may represent a potential therapeutic intervention to treat dry eye. This study examined the effect of dry eye on the response properties of corneal cool cells and the ability of the TRPM8 agonist menthol to modify these properties. A unilateral dry eye condition was created in rats by removing the left lacrimal gland. Lacrimal gland removal reduced tears in the dry eye to 35% compared with the contralateral eye and increased the number of spontaneous blinks in the dry eye by over 300%. Extracellular single-unit recordings were performed 8 -10 wk following surgery in the trigeminal ganglion of dry eye animals and age-matched controls. Responses of corneal cool cells to cooling were examined after the application of menthol (10 M-1.0 mM) to the ocular surface. The peak frequency of discharge to cooling was higher and the cooling threshold was warmer in dry eye animals compared with controls. The dry condition also altered the neuronal sensitivity to menthol, causing desensitization to cold-evoked responses at concentrations that produced facilitation in control animals. The mentholinduced desensitization of corneal cool cells would likely result in reduced tearing, a deleterious effect in individuals with dry eye.

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“…In other aspects, the local cooling causes vasoconstriction and reduces the tissue metabolism, the inflow of inflammatory mediators during penetration of needle. Also, as mentioned before, it stimulates myelinated Ad fibers, activating inhibitory pain pathways, which in turn raises the pain threshold,[ 24 ] especially to noxious stimuli such as local anesthetic agents.…”

Section: Resultsmentioning

confidence: 99%

A brief review on the efficacy of different possible and nonpharmacological techniques in eliminating discomfort of local anesthesia injection during dental procedures

et al. 2016

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Dental anxiety and fear of needle injection is one of the most common problems encountered by dental practitioners, especially in the pediatric patient. In consequences, it might affect the patient's quality of life. Several methods are suggested to lower the discomfort of local anesthesia injection during dental procedures. Desensitization of injection site is one of the recommended strategies. Among chemical anesthetic topical agents that are effective but might have allergic side effects, using some nonpharmacological and safe techniques might be useful. This study aimed to overview the efficacy of using cooling techniques, mostly by ice or popsicles, warming or pH buffering of drug, and using modern devices to diminish the discomfort of local anesthesia injection during dental procedures.

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Cold fiber heat sensitivity: dependency of ‘paradoxical’ discharge on body temperature

Cited by 19 publications

References 4 publications

Nociceptive sensations evoked from ‘spots’ in the skin by mild cooling and heating

Nociceptive sensations evoked from ‘spots’ in the skin by mild cooling and heating

Dry eye modifies the thermal and menthol responses in rat corneal primary afferent cool cells

A brief review on the efficacy of different possible and nonpharmacological techniques in eliminating discomfort of local anesthesia injection during dental procedures

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