Low dose aspirin attenuates escape/avoidance behavior, but does not reduce mechanical hyperalgesia in a rodent model of inflammatory pain

Neurosci Lett. 2001 May 25;304(3):137-40. doi: 10.1016/s0304-3940(01)01787-6.

Abstract

The present experiment examined the effect of aspirin on the escape/avoidance behavioral response to a mechanical stimulus (476 mN von Frey monofilament) in the place escape avoidance paradigm (PEAP) following subcutaneous administration of carrageenan (CARR). Forty-one male Sprague-Dawley rats received subcutaneous injection of CARR or saline in the left hindpaw and 3 1/2 h later were administered aspirin (0, 50 or 150 mg/kg). Thirty minutes later, animals were tested in the PEAP and then the mechanical paw withdrawal threshold was measured. Compared with Saline vehicle-treated controls, all CARR-treated animals displayed hyperalgesia, as reflected by enhanced responding to mechanical stimulation applied to the CARR-injected paw. Mechanical hyperalgesia was significantly reduced by the pre-treatment of 150 mg/kg, but not 50 mg/kg aspirin. In the PEAP, CARR vehicle-treated animals avoided a preferred location of the test chamber that was associated with mechanical stimulation of the hyperalgesic paw. The shift from a preferred dark side of the chamber to the light side was attenuated by pre-treatment with both doses of aspirin (50 and 150 mg/kg). The lack of anti-hyperalgesia and avoidance behavior with 50 mg/kg aspirin suggests a decrease in the aversive nature of mechanical stimulation of the afflicted paw. It is suggested that the mechanisms underlying the affective/motivational dimension of nociception (escape/avoidance) can be dissociated from the processing of nociceptive information related to withdrawal responding.

MeSH terms

  • Animals
  • Aspirin / administration & dosage*
  • Aspirin / pharmacology
  • Avoidance Learning / drug effects*
  • Carrageenan / administration & dosage
  • Dose-Response Relationship, Drug
  • Escape Reaction / drug effects*
  • Hindlimb
  • Hyperalgesia / physiopathology*
  • Inflammation / chemically induced
  • Inflammation / physiopathology*
  • Injections, Subcutaneous
  • Male
  • Pain / physiopathology
  • Physical Stimulation
  • Rats
  • Rats, Sprague-Dawley
  • Reference Values

Substances

  • Carrageenan
  • Aspirin