[Potentiating effect of clonidine on anxiolytic action of buspirone in rats].
The anxiolytic effects of buspirone (Bus) and clonidine (Clo) were studied in the social interaction (SI) test and the elevated plus-maze (EPM) in rats. Bus 1 mg.kg-1 (ip, 15 min) and Clo 10 micrograms.kg-1 (ip, 15 min) prolonged the active interaction time (AIT) in the SI test. While neither Bus 0.3 mg.kg-1 nor Clo 3 micrograms.kg-1 was effective in this model, combination of them increased AIT. Yohimbine 30 micrograms.kg-1 (ip, 15 min before Bus) reversed such a potentiating effect. On the other hand. Bus 0.3 mg.kg-1 or/and Clo 3 micrograms.kg-1 did not affect the VI (variable interval) schedule-controlled behavior. In EPM test, neither Bus 0.5 mg.kg-1 nor Clo 30 micrograms.kg-1 increased the percentages of open-arms entries (OE%) or of the time spent in open-arms (OT%). But these 2 indices were increased by combining Bus 0.5 mg.kg-1 with Clo 30 micrograms.kg-1. The results suggested that Clo potentiated the anxiolytic effect of Bus probably by its alpha 2-adrenoceptor agonist action in SI and EPM tests.