A new easy accessible and low-cost method for screening olfactory sensitivity in mice: behavioural and nociceptive response in male and female CD-1 mice upon exposure to millipede aversive odour.

In a previous study, mice were found to be repelled by the odour emitted by the millipede (Ommatoiulus sabulosus) as a defensive strategy against predators [Physiol. Behav. 74 (2001) 305-311]. To develop a standardised test for screening olfactory capabilities in rodents, we have characterised the behavioural response displayed by adult male and female CD-1 mice when exposed to a Stimulus Object (SO) consisting of a millipede-shaped sponge previously soaked either in a Toluquinone (TQ) solution (5g/100ml; Fluka), a chemical component of the exudate secreted by the millipede, or in distilled water. In Experiment 1, behaviours performed when exposed to the SO were scored (15min for 5 consecutive days). TQ exposure suppressed nearly completely Catching and Eating the SO, and increased general activity in a sex-dependent fashion. In Experiment 2, performances in a hot-plate test (50+/-0.5 degrees C, cut-off 60s) were assessed immediately after a 15-min exposure to the SO. Toluquinone-exposed mice showed a subtle yet significant decrease of pain threshold. TQ exposure assay is a new, easily testable, and low-cost method for measuring rodents olfactory sensitivity relevant for the analysis of the pharmacological agents, lesions and transgenesis.