Beta-adrenoreceptor antagonists enhance the benzodiazepine-induced suppression of footshock induced fighting in mice.

Aggressive behavior in the footshock induced fighting test (FIFT) was studied after treatment with benzodiazepines (diazepam, nitrazepam, temazepam, medazepam) given alone or in combination with beta-adrenoreceptor antagonists (propranolol, oxprenolol, practolol). With the combinations of those drugs it was found that diazepam (0.5 mg/kg) with propranolol, oxprenolol, and practolol (20 mg/kg); nitrazepam (0.25 mg/kg) with propranolol (10 mg/kg) and nitrazepam (0.1 mg/kg) with practolol (20 mg/kg); temazepam (0.5 mg/kg) with propranolol (10 mg/kg) and temazepam (1 mg/kg) with oxprenolol and practolol (20 mg/kg); medazepam (1.5 mg/kg) with propranolol (10.mg/kg) and medazepam (1 mg/kg) with practolol (20 mg/kg) produced a statistically significant decrease in frequency of fighting episodes in mice as compared with benzodiazepines alone and with control animals. The results demonstrate that beta-adrenoreceptor antagonists potentiate the antiaggressive action of benzodiazepines when given in doses which by themselves do not suppress aggression.