Pharmacological characterisation of place escape/avoidance behaviour in the rat chronic constriction injury model of neuropathic pain

Psychopharmacology (Berl). 2006 Apr;185(2):208-17. doi: 10.1007/s00213-005-0281-3. Epub 2006 Feb 15.


Rationale: Classical pain tests performed in animals routinely measure evoked nociceptive behaviours. These almost exclusively reflect sensory processing of nociceptive transmission, although a recently described place escape/avoidance paradigm may be used to selectively assess affective pain processing.

Objective: To establish if drugs with proven analgesic efficacy selectively attenuate sensory-discriminative or affective-motivational aspects of nociceptive processing.

Methods: The mu-opioid receptor agonist morphine, the anti-epileptic gabapentin, the anti-depressant duloxetine, the 5HT1A receptor agonist 8-OH-DPAT, the GABA(A) receptor agonist gaboxadol and the mixed cannabinoid receptor agonist WIN55,212-2 were tested after systemic administration in the chronic constriction injury (CCI) model of neuropathic pain. For the place escape/avoidance paradigm, CCI rats had free access between the 'non-aversive' dark and 'aversive' light side of an enclosed chamber. Either the injured or non-injured hindpaw was routinely stimulated if the rat was in the dark or light area, respectively. Escape/avoidance behaviour was defined as a shift from the dark to the light area. Mechanical allodynia and hyperalgesia were determined prior to and following escape/avoidance testing.

Results: Morphine (3 and 6 mg/kg), gabapentin (50 and 100 mg/kg), duloxetine (10 and 30 mg/kg) and 8-OH-DPAT (0.1 and 0.5 mg/kg) attenuated the time spent by CCI rats in the light area; gaboxadol (1 and 3 mg/kg) and WIN55,212-2 (0.3 and 1 mg/kg) were ineffective. Only gabapentin and 8-OH-DPAT attenuated mechanical nociceptive behaviours at non-sedative doses.

Conclusions: The place escape/avoidance paradigm may enable discrimination between selected drug classes on distinct components of sensory and affective pain processing in rats with neuropathic pain.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Analgesics / pharmacology*
  • Analgesics, Opioid / pharmacology
  • Animals
  • Anticonvulsants / pharmacology
  • Antidepressive Agents / pharmacology
  • Avoidance Learning / drug effects*
  • Chronic Disease
  • Constriction, Pathologic
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Escape Reaction / drug effects*
  • GABA Agonists / pharmacology
  • Male
  • Neuralgia / physiopathology*
  • Pain / physiopathology*
  • Pain Measurement
  • Peripheral Nervous System Diseases / physiopathology*
  • Rats
  • Rats, Sprague-Dawley
  • Serotonin Receptor Agonists / pharmacology


  • Analgesics
  • Analgesics, Opioid
  • Anticonvulsants
  • Antidepressive Agents
  • GABA Agonists
  • Serotonin Receptor Agonists