Conditioned avoidance response test

The conditioned avoidance response (CAR) test, also known as the active avoidance test, is an animal test used to identify drugs with antipsychotic-like effects by checking if they limit the animals' will. It is most commonly employed as a two-way active avoidance test with rodents. The test assesses the conditioned ability of an animal to avoid an unpleasant stimulus. Drugs that selectively suppress conditioned avoidance responses without affecting escape behavior are considered to have antipsychotic-like activity. Variations of the test, like testing for enhancement of avoidance and escape responses, have also been used to assess other drug effects, like pro-motivational and antidepressant-like effects.

Dopamine D2 receptor antagonists, like most classical antipsychotics, are active in the CAR test once occupancy of the dopamine D2 receptor reaches around 70%. Dopamine D2 receptor partial agonists like aripiprazole are likewise active in the test. Serotonin 5-HT2A receptor antagonists can enhance suppression of conditioned avoidance responses in the test. Various other types of drugs have also been found to be active in the CAR test. The effects of drugs that are active in the test are thought to be mediated by inhibition of signaling in the nucleus accumbens or ventral striatum of the mesolimbic pathway.