The presence in mice chronically treated with morphine of a substance (S) that modifies morphine responses

A principle that shortens and reduces the intensity of the abstinence syndrome to morphine in white mice was obtained from whole mouse extracts and from urine of mice chronically intoxicated with morphine pellets. Furthermore, a substance that prolongs morphine analgesia was found in extracts from mice implanted with pellets of morphine. At present, it is not known whether both principles are the same. Procedures followed to obtain the indicated principle(s) are described.