Depletion of catecholaminesin vivo induced by electrical stimulation of central monoamine pathways

It seems likely that, with certain electrode placements, the levels of stimulation used in such behavioral experiments may be effective in releasing central catecholamines.

Abstract

Intermittent electrical stimulation of central monoamine pathways has been carried out in anesthetized rats pretreated with inhibitors of amine synthesis. Depletion of catecholamines, as assessed by the histochemical fluorescence technique, was observed in DA and NA nerve terminal systems in various areas of the brain according to the area of stimulation. Without inhibition of amine synthesis no amine depletion was observed. Stimulation of the dorsal bundle (a collection of NA-containing fibere probably mainly arising from the locus coeruleus (group A6)) resulted in amine depletion mainly of NA terminals in the cortex cerebri and the hippocampal formation. Stimulation of the ventral NA bundle in the mesencephalon resulted in amine depletion mainly of NA terminals in the ventral diencephalon (e.g. hypothalamus) and the ventral parts of the limbic system. Similarly, stimulation of the DA axons arising from the zona compacta of the substantia nigra (group A9) led to depletion of amine from DA nerve terminals in the neostriatum. Stimulation in the A10 cell body area resulted in depletion of amines from NA (hypothalamus + ventral parts of the limbic system) and/or DA (limbic forebrain and/or neostriatum) nerve terminals in the tel- and diencephalon. It is suggested that these effects are the results of stimulation of DA cell bodies and fibers in this area and NA fibers of passage originating from the ventral NA bundle. As the stimulus parameters used in this study were determined in separate experiments on intracerebral self-stimulation, it seems likely that, with certain electrode placements, the levels of stimulation used in such behavioral experiments may be effective in releasing central catecholamines.