Efflux of dopamine from the synaptic cleft in the nucleus accumbens of the rat brain

Synaptic release of dopamine in the nucleus accumbens of the intact rat brain elicited by a single electrical impulse applied to ascending dopaminergic fibers results in extracellular concentrations sufficient to bind the known dopamine receptors. The dopamine concentration observed after four rapid...

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Bibliographic Details
Published in:The Journal of neuroscience 1994-10, Vol.14 (10), p.6084-6093
Main Authors: Garris, PA, Ciolkowski, EL, Pastore, P, Wightman, RM
Format: Article
Language:English
Subjects:
Animals
Dopamine - analysis
Dopamine - physiology
Dopamine - secretion
Electric Stimulation
Extracellular Space - chemistry
Extracellular Space - physiology
Male
Nomifensine - pharmacology
Nucleus Accumbens - chemistry
Nucleus Accumbens - drug effects
Nucleus Accumbens - secretion
Rats
Rats, Sprague-Dawley
Receptors, Dopamine - analysis
Sulpiride - pharmacology
Synapses - drug effects
Synapses - secretion
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Summary:Synaptic release of dopamine in the nucleus accumbens of the intact rat brain elicited by a single electrical impulse applied to ascending dopaminergic fibers results in extracellular concentrations sufficient to bind the known dopamine receptors. The dopamine concentration observed after four rapid, sequential pulses is exactly four times greater and is unaffected by pharmacological antagonism of dopamine uptake and receptor sites at supramaximal concentrations. Thus, dopamine efflux from the synaptic cleft is not restricted by binding to intrasynaptic proteins on the time scale of the measurements (50-100 msec). The extracellular concentration, as a result of a single stimulus pulse, is 0.25 microM and is rapidly removed by extrasynaptic uptake. This maximal, transient concentration of dopamine is 60 times higher than steady-state concentrations reported previously using dialysis techniques, illustrating that dopamine extracellular concentrations are spatially and temporally heterogenous. In contrast to ACh transmission at the neuromuscular junction, the dopamine synapse in the telencephalon is designed for the effective efflux of dopamine from the synaptic cleft to the extrasynaptic compartment during neurotransmission.
ISSN:0270-6474
1529-2401
DOI:10.1523/jneurosci.14-10-06084.1994