Involvement of the catecholaminergic and serotonergic mechanisms in formation of morphine addiction was investigated in mongrel male pubescent rats. Involvement of the cerebral emotiogenic neurotransmitter systems in the morphine-induced reaction and subsequent suppression of the peripheral neurotransmission link resulting from repetitive morphine administrations are initially nonspecific. Neurochemical correlates of disadaptation in the pubescent age, which results in an early drug dependence, are discussed. This may be indicative of the existence of a special risk factor within this period of ontogenesis; this factor is responsible for the development of an artificially acquired motivation to morphine, which plays the role of a reinforcement agent for the system of positive emotional reaction.