Behavioural effects of PK 8165 that are not mediated by benzodiazepine binding sites.

The phenylquinoline, PK 8165 (5-25 mg/kg), produced dose-related reductions in locomotor activity, rearing and exploratory head-dipping in a holeboard. Neither Ro 15-1788 (1, 10 or 20 mg/kg) nor CGS 8216 (1 or 10 mg/kg) was able to reverse the reductions in locomotor activity or rearing. This suggests that at least some of the behavioural effects of PK 8165 are not mediated by a site on the GABA-benzodiazepine receptor complex. This conclusion is supported by the recent report [9] that, whereas PK 8165 potently displaces benzodiazepines from their binding site in vitro, it is without effect in vivo.