Behavioural effects of pentylenetetrazole reversed by chlordiazepoxide and enhanced by RO 15-1788.

The effects of low doses of pentylenetetrazole (PTZ) on exploratory behaviour and locomotor activity in the rat, were measured in the holeboard apparatus. PTZ (30 mg/kg) significantly reduced exploratory head-dipping, an effect that was significantly reversed by chlordiazepoxide (5 mg/kg) and enhanced by RO 15-1788 (20 mg/kg). RO 15-1788 (20 mg/kg) also significantly enhanced the reduction in locomotor activity produced by PTZ (30 mg/kg); although this reduction was not reversed by chlordiazepoxide (5 mg/kg) the reduction in locomotor activity with the drug combination was no greater than that with either drug alone. The results are discussed with respect to a coupling between the benzodiazepine receptors and the site at which PTZ acts.