Journal of Neuroscience, Vol 6, 974-982, Copyright © 1986 by Society for Neuroscience
In vivo comparison of the regulation of releasable dopamine in the caudate nucleus and the nucleus accumbens of the rat brain
WG Kuhr, JC Bigelow and RM Wightman
In vivo voltammetry has been used to measure the release of dopamine evoked
by electrical stimulation of the medial forebrain bundle (MFB).
Simultaneous measurements have been made with voltammetric-sensing
electrodes ipsilateral to the stimulating electrode in the nucleus
accumbens and the caudate nucleus of the anesthetized rat. During the
stimulation, the species observed in both regions is voltammetrically
identical to dopamine. Further evidence for the identity of dopamine is
provided by anatomical, physiological, pharmacological, and postmortem
data. Postmortem analysis of these brain regions after a single stimulation
demonstrates that dopamine levels are unchanged, while
dihydroxyphenylacetic acid (DOPAC) levels are increased in both regions.
Systemic application of synthesis inhibitors results in a decrease in
evoked release for each brain region. Amfonelic acid results in a
restoration of stimulated release after synthesis inhibition. Evoked
release is affected differently by pargyline in the two brain regions. The
evoked release of dopamine is significantly elevated in the nucleus
accumbens as a result of pargyline administration, but similar effects are
not seen in the caudate nucleus. Tissue levels of dopamine are increased in
both brain regions by pargyline, but the increase is significantly greater
in the accumbens. Electrolytic lesions of the striatonigral pathway or
systemic administration of picrotoxin eliminates the pargyline-induced
difference in evoked release of dopamine. Amphetamine causes a reduction in
stimulated release in the caudate nucleus with little effect on that
observed in the nucleus accumbens.(ABSTRACT TRUNCATED AT 250 WORDS)