Effect of the serotonin agonist 8-OH-DPAT on the sensorimotor system of the rat

8-Hydroxy-2-(di-n-propylamino)-tetralin hydrobromide (8-OH-DPAT, 2 mg/kg) is used to induce perseverative behavior in rats in a T-maze as a model for obsessive-compulsive disorder (OCD). Using the open-field test, radiant heat test, and the test with von Frey filaments, we examined whether alterations in sensorimotor functioning could contribute to the perseverative tendencies in this model by measuring differences in left versus right hind paw reactions after 8-OH-DPAT administration (2 mg/kg, sc). Also, the effect of repeated 8-OH-DPAT administration on sensorimotor functioning was tested every third day. 8-OH-DPAT administration induced a significantly decreased sensorimotor performance in the open-field test, an increased threshold for noxious thermal stimulation (increased withdrawal latency, WL, and decreased elevation time, ET) in the radiant heat test, and a decreased nociceptive threshold for mechanical stimulation in the test with von Frey filaments. All changes in sensorimotor functioning were similar for left and right hind paws suggesting that, these changes as measured with the tests in the present study, are not likely to contribute to the perseverative behavior of rats in a T-maze. Further, repeated administration of 8-OH-DPAT had no effect in the radiant heat test and the test with the Frey filaments, but produced a tolerance effect in the open-field test.