Effect of rat immunization with antimorphine antibodies on morphine sensitivity and predisposition to dependence formation.

Active immunization of rats with mouse antibodies to morphine leads to the formation of antiidiotypic antibodies. This is paralleled by an increase in animal sensitivity to the analgesic and positive reinforcing effects of morphine, slower development of tolerance and formation of craving. These data indicate the possibility of active immunization against antibodies to morphine/heroin for the prevention of opium addiction relapses.