The formalin test: a validation of the weighted-scores method of behavioural pain rating

Abstract

The formalin test was developed using an ordinal scale of weighted scores to rate the intensity of pain-related behaviours in animals. However, no studies have been carried out to establish the ordinal relationship of the behavioural categories used to generate the weighted pain intensity scores. The purpose of the present study was to evaluate the validity of the weighted-scores technique by assessing the ordinality of the behavioural categories associated with the specific category weights. The amount of time spent in each of 4 behavioural categories was measured as a function of the concentration of the formalin solution injected into the hindpaw of rats, and as a function of the dose of systemic morphine given to rats injected with a concentrated (5.0%) solution of formalin. The ordinal nature of the category weights was supported when the data were subjected to a polychotomous logistic regression for fitting an ordinal model.

The bee venom test: a new tonic-pain test

“…• • 29 of analgesic drugs, as has been demonstrated for morphine in the formalin test (Coderre et al, 1993), aspirin in the formalin test (Hunskaar et al, 1986b), morphine in the tailflick test (Abbott et al, 1982b), and for morphine and aspirin in the hot-plate test (Hunskaar et al, 1986a).…”

Activation of Spinal μ- and δ-Opioid Receptors Potently Inhibits Substance P Release Induced by Peripheral Noxious Stimuli

“…Their behaviors were then observed for the next 60 min. Intradermal injection of formalin produces a biphasic nociceptive response typical of this tonic pain model (Tjølsen et al, 1992;Coderre et al, 1993). Nocifensive behaviors were assessed using a weighted score, as described previously (Dubuisson and Dennis, 1977;Coderre et al, 1993).…”

“…Intradermal injection of formalin produces a biphasic nociceptive response typical of this tonic pain model (Tjølsen et al, 1992;Coderre et al, 1993). Nocifensive behaviors were assessed using a weighted score, as described previously (Dubuisson and Dennis, 1977;Coderre et al, 1993). Nociceptive mean score was determined for each 3 min block during the recording period by measuring the amount of time spent in each of four behavioral categories: 0, the injected paw is comparable with the contralateral paw and is used normally by the animal; 1, the injected paw has little or no weight placed on it; 2, the injected paw is elevated and is not in contact with any surface; and 3, the injected paw is licked, bitten, or flinched.…”

Conjugation of a brain-penetrant peptide with neurotensin provides antinociceptive properties

“…Nocifensive behaviors were first assessed using a weighted score method, as described previously (89,90). After injection of formalin into the right hind paw, the experimenter measured the time spent in each of 4 behavioral categories: 0, injected paw is comparable to contralateral paw; 1, injected paw has little or no weight placed on it; 2, injected paw is elevated, not in contact with any surface; 3, injected paw is licked, bitten, or flinched.…”