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.