Effects of buspirone on an animal model of tardive dyskinesia

1. The effects of buspirone were studied on an animal model of tardive dysk inesia, i.e., the quantification of orofacial dyskinesia in rats repeatedly treated with reserpine. 2. Rats were co-treated with saline [SAL] or buspirone [BUS] (3.0 mg/kg, i. p., twice daily) and vehicle [VEH] or reserpine [RES] (0.1 mg/kg, s.c., onc e every other day) for 19 days. On the day 20, the animals were observed fo r quantification of the behavioral parameters of orofacial dyskinesia: tong ue protrusion and vacuous chewing movements frequencies and duration of twi tching of the facial musculature. 3. Rats of the SAL+RES group exhibited a significant increase in the three behavioral parameters of orofacial dyskinesia relative to the rats of the S AL+VEH group. However, animals of the BUS+RES group showed only an increase d frequency of vacuous chewing movements when compared to animals of the SA L+VEH group. In addition, the duration of the facial twitching was signific antly decreased in the BUS+RES group in relation to rats of the SAL+RES gro up. There were no significant differences in the orofacial parameters betwe en the BUS+VEH and the SAL+VEH groups. 4. Because it was also verified that chronic buspirone treatment was able t o increase apomorphine-induced yawning behavior, the possibility is raised that buspirone attenuates reserpine-induced orofacial dyskinesia through th e development of dopamine autoreceptor supersensitivity.