The effect of aspartic acid on the intensity of physical dependence in morphine dependent mice.

The mice (Balb/C strain) given 2% aspartic acid in 5% saccharose solution or only saccharose solution (p. os) starting 12 hr before the sc morphine pellet implantation until the removal of pellet were rendered physically morphine dependent. During the development of morphine dependence and after the removal of pellets (on 3-d day) spontaneous motor activity and analgesic threshold were measured as reliable abrupt withdrawal signs. Aspartic acid prevented to some extent the appearance of symptoms of physical morphine dependence.