A scoring system for abstinence syndrome in morphine dependent mice and application to evaluate morphine type dependence liability of drugs.

Mice were made physically dependent after 10 days morphinization and subjected to natural withdrawal. The spontaneously developing signs in behavior were classified depending on type and frequency and utilizing same a scoring system was developed. The scoring system permitted an approximate appraisal of the rise and fall of abstinence state up to 10 hr after the start of withdrawal. When the single suppression technique was applied, it thus became possible to generally estimate the dependence liability of a given drug and at the same time, to determine whether or not a drug could be substituted for an opiate thereby predicting the liability of morphine-type dependence.