Benzodiazepines impair a behavioral effect induced by stimulation of 5-HT1B receptors

Seven days of isolation induce in mice a social behavioral deficit (decrease in escape attempts) reversed by TFMPP acting through activation of 5-HT1B receptors. The present experiments were performed to investigate the interaction between tranquillizing drugs and one aspect of the serotonergic functioning through the TFMPP-induced increase in escape attempts. The benzodiazepines diazepam, alprazolam, triazolam and chlordiazepoxide impaired significantly TFMPP-induced increase in escape attempts at behaviorally inactive doses. Buspirone opposed TFMPP effect, but the active doses 4 and 16 mg/kg alone decreased the number of escape attempts. ICS 205-930 in a large dose range (0.001-1 mg/kg) modified neither the number of escape attempts nor the increase induced by TFMPP. Chronic (11 days) treatment with buspirone (16 mg/kg) or ICS 205-930 (1 mg/kg) modified neither the number of escape attempts of isolated mice nor the increase induced by TFMPP. These results suggest that tranquillizing drugs of the benzodiazepines group, but not of other groups, interact with the 5-HT1B receptors; they add to the knowledge of relations between benzodiazepines and serotonin by specifying the involvement of 5-HT1B receptors.