DIFFERENTIAL TEMPORAL DYNAMICS OF SERUM AND BRAIN COCAINE - RELATIONSHIP TO BEHAVIORAL, NEUROENDOCRINE AND NEUROCHEMICAL COCAINE-INDUCED RESPONSES

Rats administered cocaine 10 mg/kg i.p. exhibited hyperlocomotion which occurred within 5 min post injection. Subsequently, rats were injected with 10 mg/kg cocaine and brain and serum concentrations of cocaine were measured at 5, 10, and 20 min post injection. Within this time frame, cocaine concentration in limbic brain tissue was maximal at 5 min post injection and then declined substantially by 20 min post injection. In contrast, serum cocaine concentration increased from 5 to 20 min. post injection. Neurochemical effects of cocaine upon limbic dopamine turnover and plasma corticosterone had a time course similar to serum cocaine. Brain cocaine concentrations paralleled the locomotor stimulant cocaine response whereas cocaine neuroendocrine effects paralleled serum cocaine concentrations. These findings point to the importance of brain cocaine concentration determinations in neurobehavioral studies of cocaine.