Effect of nitrazepam and its combined administration with fenfluramine and cyproheptadine on explorative behaviour, muscle tone and coordination in normal mice and in mice with isolation syndrome.

The benzodiazepine nitrazepam, which has a marked hypnotic effect in human subjects and a myorelaxating effect in mice with aggressive behaviour, was applied in non-isolated and isolated non-aggressive and aggressive mice. The observed weaker inhibition of exploration behaviour is isolated mice (mice with isolation syndrome) compared with non-isolated mice suggests the significance of the functional activity of the serotoninergic system in the brain for the manifestation of the effects of the drug, since in mice with isolation syndrome the serotonin turnover is changed. The results obtained by combined application of nitrazepam with cyproheptadine suggest that nitrazepam exercises its influence partly by stimulation of the postsynaptic serotonin receptors. Combined application of nitrazepam with fenfluramine shows that serotonin and to a lesser extent the remaining neurotransmitters affected by fenfluramine play a considerable role in the mechanism of action of this benzodiasepine.