The up-and-down method for the determination of nociceptive thresholds in rats.

The up-and-down method applied to the jump-flinch technique provided estimates of shock thresholds for jump and flinch with high statistical efficiency and a much reduced amount of experimentation compared with traditional methods. Reproducible results were obtained after repeated testing and flinch and jump thresholds were significantly increased by treatment with morphine or oxotremorine.