BENZODIAZEPINE RECEPTOR LIGANDS HAVE NO SPECIFIC ACTION ON WORKING-MEMORY IN A DELAYED CONDITIONAL DISCRIMINATION TASK IN RATS

We investigated effects of benzodiazepine (BDZ) receptor ligands on working memory in a delayed conditional discrimination (DCD) task The BDZ receptor full agonist midazolam (0.1-1.0 mg/kg) dose-dependently impaired performance independent of delay, indicating no specific effect on working memory. The non-sedative BDZ receptor partial agonist bretazenil (0.06-0.6 mg/kg), the inverse agonist beta-CCM(0.05-0.45 mg/kg), the partial inverse agonist FG 7142 (0.5-5.0 mg/kg), the antagonist flumazenil (1-10 mg/kg), and the antagonist ZK 93 426 (1-10 mg/kg) did not significantly affect performance. It is concluded that BDZ ligands do not affect working memory in a positively-motivated DCD task Midazolam also impaired performance in the no-delay condition, suggesting loss of stimulus control, possibly through an attentional impairment.