Effects of central and systemic injections of peripheral benzodiazepine receptor ligands on the anxiolytic actions of ethanol in rats

The influence of peripheral benzodiazepine receptor ligands Ro5-4864 (0.05 or 1.0 mg/kg, i.p.) or PK11195 (0.05 or 1.0 mg/kg, i.p.) on the anxiolytic effect of ethanol (1.2 g/kg; 14% p/v; i.p.) was investigated in rats tested on the elevated plus-maze. Other animals were injected through intrahippoc ampal administrations of the ligands (0.5 or 1.0 nmol/0.5 mul) before ethan ol (1.2 g/kg; 14% p/v; i.p) and submitted to the elevated plus-maze test. T he results showed that the systemic administration of either ligands 24 hou rs before the ethanol treatment resulted in a reduced anxiolytic effect of this drug. Only PK11195 reversed the effect of ethanol after intrahippocamp al injection. These data suggest that peripheral benzodiazepine receptors p lays a role in ethanol anxiolysis.