Polish journal of pharmacology
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The drug addiction may be regarded as the disease of the brain reward system. This system, closely related to the system of emotional arousal, is located predominantly in the limbic structures of the brain. Its existence was proved by demonstration of the "pleasure centers," that were discovered as location from which electrical self-stimulation is readily evoked. ⋯ The adaptation of an organism to a chronic intake of drugs involves development of adaptive changes, sensitization or tolerance. It is thought that the gap between sensitization developing for the incentive value of the drug and tolerance to the reward induced by its consumption underlies the vicious circle of events leading to drug dependence. The vulnerability to addiction is dependent not only on the environment, but also on genetic factors.