Potential anxiolytic properties of R-(+)-8-OSO2CF3-PAT, a 5-HT 1A receptor agonist

The anxiolytic property of R-(+)-8-OSO2CF3-PAT(R-(+)-8- [[(trifluoromethyl)sulfonyl]oxy]-2-(n-propyl-amino)tetralin), a 5-HT1A receptor agonist, was evaluated in Wistar rats by means of animal models of anxiety, the conditioned defensive burying model and the conditioned stress-induced freezing response followed by the elevated plus-maze test, respectively. In addition, the 5-HIAA/5-HT ratio (5-hydroxy-indole acetic acid/5-hydroxytryptamine) of rat brain homogenates was studied. Acute drug administration resulted in abolition of the burying behaviour (3 mg/kg i.p.), a dose-dependent decrease of rearing and induction of hyperphagia. R-(+)-8-OSO2CF3-PAT had no effect on conditioned footshock-induced freezing behaviour but increased open-arm activity in the rats on the plus-maze. The 5-HIAA/5-HT ratio was decreased in the lateral septum (1 and 3 mg/kg), dorsal hippocampus (3 mg/kg) and somatosensory cortex (3 mg/kg), implying that R-(+)-8-OSO2CF3-PAT affects particularly the limbic system in anxiety-inducing situations.