Naloxone blocks the effect of diazepam and meprobamate on conflict behaviour in rats

The effect of naloxone on the anticonflict action of diazepam was studied in a model involving foot shock-induced suppression of food-rewarded operant behaviour. Both 1 and 10 mg/kg naloxone SC abolished the increase in punished responding produced by diazepam and chlordiazepoxide. Naloxone also blocked the anticonflict effect of meprobamate. These observations are discussed in terms of a possible involvement of endogenous opioid peptides in the anxiolytic effects of tranquillizers.