SUSTAINED 5-HYDROXYTRYPTAMINE RELEASE-INHIBITORY AND ANXIOLYTIC-LIKE ACTION OF THE PARTIAL 5-HT(1A) RECEPTOR AGONIST, BUSPIRONE, AFTER PROLONGED CHRONIC ADMINISTRATION

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