DIFFERENT BEHAVIORAL PROFILES OF THE R(-ENANTIOMER AND S(-)-ENANTIOMER OF 8-HYDROXY-2-(DI-N-PROPYLAMINO)TETRALIN IN THE MURINE ELEVATED PLUS-MAZE())

(+/-)8-Hydroxy-2-(di-n-propylamino)tetralin (8-OH-DPAT) has been the m ost widely used pharmacological tool in research on 5-HT1A receptor fu nction. In the present study, the behavioural effects of 8-OH-DPAT ent antiomers were compared using an ethological version of the murine ele vated plus-maze test. Subcutaneous pretreatment (-20 min) with R(+)-8- OH-DPAT (0.03-1.0 mg/kg) produced a pronounced and dose-dependent beha vioural suppression (decreased open/closed/total arm entries and incre ased nonexploratory behaviours). In contrast, over the same dose range , S(-)-8-OH-DPAT reduced several ethological indices of anxiety withou t altering the majority of conventional parameters or general activity levels, e.g, arm entries and per cent time measures, as well as head dipping, Findings are discussed in relation to differences in the intr insic activity of 8-OH-DPAT isomers at 5-HT1A sites and the putative r ole of these receptors in anxiety-related processes. The differential behavioural profiles of 8-OH-DPAT enantiomers suggest that racemic 8-O H-DPAT may not be an ideal tool for research on the behavioural pharma cology of 5-HT1A receptors.