EFFECTS OF THE BENZODIAZEPINE RECEPTOR INVERSE AGONIST, DMCM, ON THE BEHAVIOR OF MICE - AN ETHOPHARMACOLOGICAL STUDY

Ethopharmacological procedures and a two-compartment black and white test box were used to examine behavioural effects produced by the benzodiazepine receptor inverse agonist, methyl-6,7-dimethoxy-4-ethyl-beta-carboline-3-carboxylate (DMCM), when given by intraperitoneal injection (0.4 and 1.0 mg/kg) to pair-housed adult CD1 male mice. Control mice received injections of the solvent. Behaviour in the light-dark box was examined at 30 min after the injection and behaviour during encounters with an untreated group-housed male, in a neutral cage, was then assessed by ethological procedures. In dominant mice, aggressive behaviour was significantly reduced and the ratio of flight, relative to aggression received, was significantly increased by DMCM at 0.4 mg/kg. At 1 mg/kg but not 0.4 mg/kg, DMCM decreased time spent by dominant mice in the light compartment of the test box. In both dominant and subordinate mice, flight was increased by DMCM at 1 mg/kg to a level close to statistical significance. Treatment with DMCM had no other detectable effect on the behaviour of subordinate animals. It is suggested that anxiogenic activity of this compound might induce a shift of agonistic behaviour from aggression to "fear-induced flight".