Subthalamic nucleus microinjections of 5-HT2 receptor antagonists suppressstereotypy in rats

The subthalamic nucleus (STN) is an important mediator of basal ganglia out put. We studied the effects of STN microinjections of the serotonin-2 (5-HT 2) antagonists clozapine, mesulergine and M100,907 on apomorphine-induced s tereotypic activity in the rat. Each compound profoundly decreased the expr ession of stereotypic behavior, with particularly strong effects to reduce gnawing behavior. Because M100,907 does not have appreciable affinity for d opamine D-1 and D-2 receptors, and since all three agents are 5-HT2 antagon ists, the current data suggest that basal ganglia output related to orofaci al movements can be significantly modified by 5-HT2 receptors. The results suggest that antipsychotics with serotonergic properties may have direct ac tions on the STN that influence their potential to produce orofacial and ot her motor side effects. NeuroReport 11:267-270 (C) 2000 Lippincott Williams & Wilkins.