Housing conditions and the anxiolytic efficacy of buspirone: the relationship between main and side effects

Serotonergic anxiolytics yield contradictory results both in the laboratory and clinically. In an attempt to investigate the cause of discrepancies, t he anxiolytic effect of buspirone (0, 3 or 10 mg/kg, single treatment) was tested 1 h and 4 h after injection in rats In different housing conditions. At 1 h after drug administration, buspirone increased corticosterone produ ction and decreased locomotor behaviour in both the elevated plus-maze and the social interaction tests. No anxiolytic-like effect was produced in eit her test. At 4 h after drug injection, no corticosterone or locomotor effec ts of buspirone were observed. In contrast, anxiolytic effects emerged in t his phase, Open arm exploration and social investigation were increased in the plus-maze and social interaction test, respectively. In the plus-maze, the anxiolytic effect was significant in isolated animals only. In the soci al interaction test, the anxiolytic effect was stronger in isolated than in group-housed animals. When corticosterone secretion was inhibited by adren alectomy, a full anxiolytic effect of buspirone was observed 1 h after drug administration. It appears that the side effects of buspirone have a short er duration than the main anxiolytic effect. The buspirone-induced increase in corticosterone may have abolished the anxiolytic effects of the drug sh ortly after injection. Individual housing enhanced the anxiolytic efficacy of buspirone 4 h after administration. (C) 2000 Lippincott Williams & Wiiki ns.