A comparative study of the effects of muscimol and diazepam on the recall of noxious events

Effects of benzodiazepines on acquisition and performance: a critical assessment

Evidence related to the effects of benzodiazepines on learning and memory is reviewed in the contexts of human verbal learning studies and animal studies using both aversive and non-aversive paradigms. While the impairment of acquisition by benzodiazepines appears to be a robust phenomenon generalizing across species and experimental conditions, the impairment in the performance of an already-learned task by such drugs appears to be more restrictive and highly dependent upon experimental contingencies. Thus far, performance impairment appears to be found mainly in animal studies using non-aversive, food-motivated tasks, with such tasks being particularly well suited for investigating such a phenomenon. At present, there is a noticeable lack of knowledge regarding the neurochemical substrates underlying BDZ-induced impairment. Finally, some issues that may contribute to the presence or absence of a BDZ-induced performance impairment in published studies are briefly considered.

Some evidence for amnesic-like effects of benzodiazepines in animals

In animals, as in humans, benzodiazepines affect memory, inducing almost exclusively an anterograde amnesia. The characteristics of this amnesic-like effect are reviewed in terms of alterations in acquisition, consolidation, recall and/or forgetting processes. Explanations alternative to a true amnesia, i.e., state-dependent learning, cognitive deficits, attenuation of the emotional weight of the conditioning events are examined. Finally, the interference of these putative amnesic effects with experimental procedures devoted to the study of the anxiolytic activities of benzodiazepines are considered.

The comparative effects of benzodiazepines, progabide and PK 9084 on acquisition of passive avoidance in mice

Acquisition of passive avoidance following aversive conditioning to a dark compartment was measured in mice under the influence of one of seven benzodiazepines, the GABA-mimetic drug progabide or PK 9084, a nonbenzodiazepine ligand on benzodiazepine receptors. The drugs were administered prior to the training trial and retention was measured in the absence of the drug 24 h later. Oral administration (dose in mg/kg in parentheses) of flunitrazepam (0.1), lorazepam (1.0), nitrazepam (3.0), diazepam (10), flurazepam (10) and chlordiazepoxide (30), all prevented retention whereas progabide (100-800) and PPK 9084 (10-100) were ineffective. In comparison to effects on motor capacity none of the benzodiazepines was outstanding in its acquisition interfering effects.

Diazepam-induced release of behavior in an extinction procedure: its reversal by Ro 15-1788

The effects of the benzodiazepine receptor antagonist Ro 15-1788, an imidazobenzodiazepine derivative, were studied with respect to three pharmacological activities exerted by diazepam in rats. Two of these, release of shock-induced suppression of drinking and attenuation of non-reward-induced cessation of responding for food, reflect the anxiolytic property of benzodiazepines. The amnesic-like effect of diazepam was also investigated. Ro 15-1788 (in doses ranging from 4 to 16 mg/kg p.o.) completely reversed diazepam (2 mg/kg)-induced release of behavior in both punishment and non-reward procedures. In contrast, Ro 15-1788 reduced but did not completely abolish diazepam-induced amnesia. These data suggest that the anticonflict and anti-frustration effects of benzodiazepines probably involve similar receptor types which nevertheless differ from those chiefly implicated in the amnesic-like activity of benzodiazepines.