Abstracts Psychology

Quantifying formalin-induced behaviours and morphine analgesia

by Rok. Ocvirk

The present investigation validated a time-sampling method of scoring formalin-induced pain-specific behaviours. The method improves efficiency by at least a factor of five, and also provides measures of other aspects of behaviour, without the loss of statistical power of the results. Formalin-induced behaviours were examined over the entire range of commonly used formalin concentrations, for a prolonged period of time. The pain response increased dose-dependently up to 2% formalin in the first phase and up to 10% in the second phase if behaviour was scored for at least 90 minutes postformalin. Significant residual pain occurred only at 10% formalin. When morphine dose-effect relationships were examined at varying formalin concentrations, there was a systematic rightward shift in the morphine dose-effect relationships up to about 2% formalin, at which point, further increases in formalin concentration did not produce any further shift, and morphine appeared to noncompetitively antagonize formal in-induced pain. (Abstract shortened by UMI.)