Enhancing effects of Hoe 175 on memory in mice.

These experiments investigated the effects of the nootropic compound Hoe 175 [3,8-dimethyl-4-phenyl-5,6,7,8-tetrahydro-pyrazolo-(3,4-b) (1,5)-diazepine-1H,4H-5,7-dione] on retention performance of mice in three training tasks. When administered prior to both training and retention testing on a one-trial inhibitory avoidance task, Hoe 175 (6-25 mg/kg PO) attenuated the amnestic effect of transcorneal electroconvulsive shock. Post-training administration of Hoe 175 enhanced retention of otherwise untreated mice in both inhibitory (3-12 mg/kg IP) and active avoidance (1-25 mg/kg IP) learning tasks. The drug was most effective at intermediate doses. The enhancing effect of post-training administration of Hoe 175 was time-dependent: enhancement of retention was obtained with injections administered 2 h but not 6 h after training. The findings are interpreted as suggesting that Hoe 175 affects retention performance through influences on memory storage and retrieval.