Sustained 5-hydroxytryptamine release-inhibitory and anxiolytic-like action of the partial 5-HT1A receptor agonist, buspirone, after prolonged chronic administration.

The effect of prolonged administration of high doses of buspirone on its 5-hydroxytryptamine (5-HT) release-inhibitory and anxiolytic-like properties was investigated. The 5-HT release-inhibitory effect of a challenge dose of buspirone (0.5 mg/kg, s.c.) was identical in rats chronically treated with vehicle or buspirone (10 mg/kg, b.i.d. for 10 weeks), as estimated by in vivo microdialysis in the ventral hippocampus. In the same set of animals there was a significant anxiolytic-like effect in the elevated plus-maze after 5 weeks of treatment with buspirone. The results indicate that the functional capacity of 5-HT release-controlling 5-HT1A autoreceptors is retained upon chronic administration of buspirone, and that this effect may well be associated with the anxiolytic-like action of the compound.