Overview of the study

Our study describes the results of five electrochemical experiments conducted in awake, freely-moving rats. In two experiments, we examined the effects of intravenous heroin on extracellular levels of oxygen (experiment 1) and glucose (experiment 2) in the NAc. To clarify possible mechanisms underlying heroin-induced changes in NAc oxygen and glucose, in two experiments we examined the effect of intravenous heroin on oxygen (experiment 3) and glucose (experiment 4) levels in the subcutaneous space. To explore the relationship between changes in oxygen, glucose, and metabolic brain activation, we analyzed oxygen and glucose data in conjunction with data from a thermorecording experiment (experiment 5), in which we assessed heroin-induced temperature changes recorded in the NAc, temporal muscle, and skin. In experiment 6 we examined the effects of heroin at a very high dose (3.2 mg/kg) within the range of presumed overdose, on NAc oxygen, glucose, and multiple temperature parameters.