Anxiolytic effect of the 5-HT_1A compounds 8-hydroxy-2-(di-n-propylamino) tetralin and ipsapirone in the social interaction paradigm: Evidence of a presynaptic action

This study analyses at which site, pre- or postsynaptic, the 5-HT_1A ligands-8-hydroxy-2(dl-n-propyilamino)tetralin (8-OH-DPAT) and ipsapirone-induce their amdoytic action. The experimental anxiety was assessed in the social interaction test. An anxioyfic action was observed after the systemic administration of 8-OH-DPAT (025 and 0.5 mg/kg and ipsapirone (5 but not 10 mg/kg). In 5,7-dihydroxytrpytamine (5,7-DHT, 150 μg 10 μl) lesioned rats the arodoytie effect of 8-OH-DPAT and ipsapirone was not observed, suggesting a presynaptic action of these drugs.dnVs. When directly injected into the dorsal raphe nucleus 8-OH-DPAT (0.1 μgμl) and ipsapirone (0.2 μg/μl), both compounds produce an)dolytic effects. At same doses, these drugs lacked an effect after their intrahippocampal infusion. All data strongly suggest that both drugs act presynaptically to reduce the anxiety levels in the social interaction paradigm.