Abstract: The experiment studied the changes of behaviors and brain contents ofmonoamine neurotransmitters in 64 rats with morphine addiction that wereaffected by daily drinking and hypodermic injection of morphine. The resultshowed that both drinking and injection of morphine could bring all of therats into morphine dependent condition at the fourth week of the experiment.The morphine dependent rats obviously preferred solution of morphine andwater to water, and the morphine intake was stabilized at approx. 35mg/kg/day. If the drug stopped suddenly, the rats became active, then the foodintake decreased and body wieght reduced. At the same time, the conditionedfood-seeking running accelerated and the mistakes made at the turninggreatly decreased, The transmitter contents of monoamines in the wholebrain of morphine dependent rats also changed, NE and DA slightlydecreased, but 5--HT and 5--HIAA markedly increased. Whether thesechanges are primary or secondary needs further study.

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