Pinch-induced catalepsy in mice: a useful model to investigate antidepressant or anxiolytic drugs.

1. Repeated pinching at the scruff produces, in experimental test/retest sessions, prolonged cataleptic-like immobility in mice that may mimic immobilities seen in some natural situations. 2. In the first experiment, on male mice, imipramine and amitriptiline (20 and 30 mg/kg i.p.) augmented the number of pinches necessary to reach the criterion of induced catalepsy and reduced the total time of catalepsy. 3. In the second experiment, on female mice, compounds that modulate the central 5-HT transmission, like fluvoxamine, fluoxetine (20 mg/kg i.p.) and ondansetron (0.1 and 1 mg/kg i.p.), retarded the occurrence and shortened the duration of pinch induced catalepsy at doses that did not modify the open field performances. Maprotiline (a selective inhibitor of the NA reuptake) did not modify the mice's performances in respect to controls. 4. Female mice presented a more rapid occurrence and a prolonged duration of pinch-induced catalepsy in respect to male controls. The present behavioral test may become a simple experimental model to detect new antidepressant or anxiolytic compounds and the significant sex difference could make the test a more useful tool in investigating anxiety behaviour in rodents.