The ITFR, impulsive tail flick reflex by short duration nociceptive stimuli

Massimo Leandri, Silia Leandri, Mariaisabella Ghignotti, Michele Cilli, Gianluigi Lunardi

Research output: Contribution to journalArticlepeer-review


A new method for evoking the tail flick reflex is introduced, using short duration or "impulsive" nociceptive stimuli, which allow synchronization and recording of electrophysiological responses. Ten adult rats were studied, by means of thermal (CO2 laser infrared pulse with 30ms duration, 7.5 or 10W), electric (a 25ms train of five 0.2ms pulses, with 5 or 10mA intensity) or mechanical (pin pressed with 5g force) stimuli. Both electromyographic and strain gauge mechanical responses were recorded from the tail. All three types of stimulation gave rise to three components, named early, late and ultralate, respectively occurring in the range of 19-97ms, 190-519ms, 1523-2765ms. Conduction velocities of the underlying afferent fibres were calculated by moving the stimulation site. The early component could be linked to Aδ afferents, while late and ultralate components were due to unmylinated C afferents. Experiments with Fentanyl (20μg/kg) showed that only the C linked components were depressed, with the ultralate component the most affected, possibly because supraspinally originated. Tail flick reflex evoked by impulsive stimuli is believed to be an important electrophysiological complement to behavioural procedures, useful in identifying the site of action of analgesics and other drugs upon the spinal and supraspinal centres involved in nociception.

Original languageEnglish
Pages (from-to)69-77
Number of pages9
JournalJournal of Neuroscience Methods
Issue number1
Publication statusPublished - Jul 15 2011


  • Analgesics
  • EMG
  • Laser
  • Neurophysiology
  • Nociception
  • Strain gauge
  • Tail flick

ASJC Scopus subject areas

  • Neuroscience(all)


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