Modality-specific hyper-responsivity of regenerated cat cutaneous nociceptors

Research output: Contribution to journalArticle

Abstract

1. Experiments were performed on anaesthetized cats to investigate the receptive properties of regenerated cutaneous tibial nerve nociceptors, and to obtain evidence for coupling between them and other afferent fibres as being possible peripheral mechanisms involved in neuropathic pain. These properties were studied 6-7 months after nerve section and repair. 2. Recordings were made from 25 regenerated nociceptors; 14 were A fibres and the remainder were C fibres. Their receptive field sizes and conduction velocities were similar to controls. There was no significant difference between their mechanical thresholds and those of a control population of nociceptors. 3. Regenerated nociceptors were significantly more responsive to suprathreshold mechanical stimuli than were uninjured control fibres. This increase in mechanical sensitivity occurred in both A and C fibres, although A fibres showed a greater increase in mechano-sensitivity than C fibres. Over half of the regenerated nociceptors (13/25) showed after-discharge to mechanical stimuli which was never seen in controls; the mean firing rate during this period of after-discharge was significantly related to both stimulus intensity and stimulus area. 4. There was no significant difference between the heat encoding properties of regenerated nociceptors and control nociceptors. Cold sensitivity was similarly unchanged. Thus, abnormal peripheral sprouting was unlikely to account for the increased mechanical sensitivity of the regenerated fibres. None of the regenerated nociceptors were found to be coupled to other fibres. 5. These results suggest that the clinical observation of mechanical hyperalgesia in patients after nerve injury may have a peripheral basis. Based on this model, other signs of neuropathic pain (i.e. tactile or thermal allodynia) are more likely to be due to altered central processing.

Original languageEnglish (US)
Pages (from-to)897-906
Number of pages10
JournalJournal of Physiology
Volume516
Issue number3
DOIs
StatePublished - May 1 1999
Externally publishedYes

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Nociceptors
Cats
Skin
Myelinated Nerve Fibers
Unmyelinated Nerve Fibers
Hyperalgesia
Neuralgia
Tibial Nerve
Hot Temperature
Observation
Wounds and Injuries

ASJC Scopus subject areas

  • Physiology

Cite this

Modality-specific hyper-responsivity of regenerated cat cutaneous nociceptors. / Andrew, D.; Greenspan, Joel Daniel.

In: Journal of Physiology, Vol. 516, No. 3, 01.05.1999, p. 897-906.

Research output: Contribution to journalArticle

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