Interactions of Ro 15-1788, CGS 8216 and diazepam on head-turning in rats

Ro 15-1788 (10 mg/kg, ip) and CGS 8216 (10 mg/kg, ip) significantly reversed the inhibitory effect of diazepam (5 mg/kg, ip) on electrically induced head-turning in rats. Neither antagonist alone, at the dose level which blocked diazepam, had any intrinsic activity in this model. The specificity of the interaction between CGS 8216 and diazepam was further confirmed by the lack of antagonism by CGS 8216 of muscimol's inhibitory effect on head-turning. These results provide additional evidence that the inhibition of head-turning induced by diazepam is mediated via the benzodiazepine binding site. Furthermore, this model provides a functional expression of the interaction between the benzodiazepine recognition site, the chloride ionophore, and the GABA receptor complex.