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 (0.1-1.0mg/kg) dose-dependently impaired performance independent of delay, indicating no specific effect on working memory. The non-sedative BDZ receptor partial agonist bretazenil (0.06-0.6mg/kg), the inverse agonist beta-CCM (0.05-0.45mg/kg), the partial inverse agonist FG 7142 (0.5-5.0mg/kg), the antagonist flumazenil (1-10mg/kg), and the antagonist ZK 93 426 (1-10mg/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.
Herremans
A.H.J.
AH
Department of Psychopharmacology, Rudolf Magnus Institute for Neurosciences, Faculty of Pharmacy, Utrecht University, PO Box 80082, 3508 TB Utrecht, The Netherlands.
Hijzen
T.H.
TH
Olivier
B.
B
Slangen
J.L.
JL