Amphetamine and noradrenergic reward pathways

Abstract

Publisher Summary This chapter reviews amphetamine and noradrenergic reward pathways. The effects of norepinephrine, and dopamine on self-stimulation were directly examined by injecting these agents in the lateral ventricle through permanently-indwelling cannulas. l-Norepinephrine facilitated medial forebrain bundle self-stimulation over a wide range of doses. Similar doses of dopamine are much less effective, or may even suppress self-stimulation. The mild facilitating effects of dopamine are sometimes observed after a delay of several minutes, and thus may reflect conversion of the dopamine to norepinephrine. It is found that to further evaluate the hypothesis that dopamine mediates rewarding effects, rostally-projecting dopamine pathways were mapped for self-stimulation at points in the brain where a somewhat better separation of noradrenergic, and dopaminergic systems than that in the substantia nigra is described. Self-stimulation was obtained from some electrodes in the dopamine tracts of the internal capsule, particularly from sites surrounding the tip of the crus cerebri, but maximal rates were only about 20% of the maximal rates obtained from medial forebrain bundle electrodes.