Pharmacological validation of an automated method of pain scoring in the formalin test in rats.
In 1997, we described a new automated method of scoring the pain behaviors in the formalin test. The algic behavior was automatically measured with the help of a video-analysis system. The time during which the animal grooms, licks, or bites itself was used as the parameter of pain. In the present study, we tested various analgesics to realize a pharmacological validation of the system. The effect of opiate analgesic (morphine, i.v.), nonsteroidal anti-inflammatory drugs (paracetamol, i.v., piroxicam, i.v., indomethacin, i.v.), antidepressant drugs (clomipramine, desipramine, nortryptyline, and paroxetine, i.p.), and serotonin (i.t.) were analyzed. A dose of 1.25 mg/kg of morphine induced a decrease in the scores of phases 1 and 2. Naloxone (0.25 mg/kg) reversed the effect of morphine (2.5 mg/kg). A 20-mg/kg dose of indomethacin induced a decrease in the second phase, and paracetamol induced a decrease in both phases (analgesic doses were 400 mg/kg and 200 mg/kg for first and second phases, respectively). Piroxicam had no effect on the pain scores. Clomipramine, desipramine, and paroxetine at a dose of 5 mg/kg induced a significant decrease in the second phase. Nortriptyline had no effect on the pain scores. A dose of 75 microg of serotonin induced a decrease in both phases 1 and 2. This study demonstrated that this system shows a good pharmacological sensitivity, although it is lower than that of manual assessment.
Jourdan
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INSERM EPI9904, Laboratoire de Pharmacologie Médicale, Faculté de Médecine, 63001, Clermont-Ferrand Cedex, France.
Alloui
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Eschalier
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D000700:Analgesics / Q000627:therapeutic use*; D000818:Animals; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D000928:Antidepressive Agents / Q000627:therapeutic use; D001331:Automation; D001522:Behavior, Animal / Q000187:drug effects*; D004347:Drug Interactions; D005557:Formaldehyde / Q000633:toxicity*; D007091:Image Processing, Computer-Assisted / Q000379:methods; D008297:Male; D009020:Morphine / Q000627:therapeutic use; D009270:Naloxone / Q000494:pharmacology; D010146:Pain / Q000188:drug therapy* / Q000517:prevention & control; D010147:Pain Measurement; D051381:Rats; D017207:Rats, Sprague-Dawley; D015203:Reproducibility of Results; D012701:Serotonin / Q000627:therapeutic use
D000700:Analgesics; D000894:Anti-Inflammatory Agents, Non-Steroidal; D000928:Antidepressive Agents; D005557:Formaldehyde; D012701:Serotonin; D009270:Naloxone; D009020:Morphine