Spontaneous alternation behavior: an animal model for obsessive-compulsive disorder?

This study entailed the adoption of a well-established behavioral paradigm, spontaneous alternation, as a possible animal model for some of the symptoms observed in obsessive-compulsive disorder (OCD) in humans. Food-deprived rats were run in a T-maze in which both a black and a white goal box were equally baited with a small amount of chocolate milk. Each rat was given 7 trials every other day during which it was placed in the start box and allowed to make a choice. The mean number of choices until an alternation occurred was recorded. After a stable baseline of spontaneous alternation was achieved the effects of manipulating the serotonergic system were tested. Both the nonselective 5-HT agonist 5-MeODMT (1.25 mg/kg) and the more selective 5-HT1A agonist 8-OH-DPAT (2 mg/kg) disrupted spontaneous alternation. A course of chronic treatment (2 x 5 mg/kg for 21 days) with the selective 5-HT uptake blocking agent fluoxetine had a protective effect on the 5-MeODMT-induced disruption of spontaneous alternation behavior. Serotonergic manipulations of spontaneous alternation may be a simple animal model for the perseverative symptoms or indecisiveness seen in people diagnosed with OCD.