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Vol. 289, Issue 1, 455-463, April 1999
Departments of
Pharmacology (A.F.H., G.A.G.) and
Psychiatry
(G.A.G.),
Neuroscience Training Program (G.A.G.), and
Rocky Mountain
Center for Sensor Technology (G.A.G.), University of Colorado Health
Sciences Center, Denver, Colorado
The properties of dopamine (DA) release in the rat substantia nigra
(SN) and striatum were investigated using high-speed chronoamperometric recordings in brain slices. In both brain regions, a 2-min bath superfusion with 30 mM KCl produced robust DA-like electrochemical signals, with the mean amplitude of the signal being >10-fold greater
in the striatum than the SN. The reproducibility of the response was
confirmed by a second stimulus (S2)/first-stimulus (S1) ratio of >0.8
in both regions. The bath application of tetrodotoxin significantly
reduced the S2/S1 ratio in both the striatum and SN, implicating the
requirement for voltage-sensitive sodium channels in the DA-release
process. However, the application of cadmium chloride, a nonselective
blocker of voltage-sensitive calcium channels, reduced the S2/S1 ratio
only in the striatum and not within the SN. Moreover, removal of
Ca2+ from the buffer did not significantly affect release
within the SN, despite a >85% reduction in release within the
striatum. In addition, although the D2 receptor antagonist
sulpiride enhanced the S2/S1 ratio in the striatum, no effect of this
agent was seen in the SN. Finally, the application of
d-amphetamine produced DA-like electrochemical signals
in both the striatum and SN. However, the amplitude of the
d-amphetamine-evoked response, relative to the
KCl-evoked release, was much smaller in the striatum than in the SN.
Taken together, these data support the hypothesis that differences in
the mechanism or mechanisms of release exist between somatodendritic
and axonal elements within the nigrostriatal pathway.
This article has been cited by other articles:
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 C. P. J. de Kock, L. N. Cornelisse, N. Burnashev, J. C. Lodder, A. J. Timmerman, J. J. Couey, H. D. Mansvelder, and A. B. Brussaard NMDA receptors trigger neurosecretion of 5-HT within dorsal raphe nucleus of the rat in the absence of action potential firing J. Physiol., December 15, 2006; 577(3): 891 - 905. [Abstract] [Full Text] [PDF]
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B. T. Chen and M. E. Rice Novel Ca2+ Dependence and Time Course of Somatodendritic Dopamine Release: Substantia Nigra versus Striatum J. Neurosci., October 1, 2001; 21(19): 7841 - 7847. [Abstract] [Full Text] [PDF]
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 B. H. Falkenburger, K. L. Barstow, and I. M. Mintz Dendrodendritic Inhibition Through Reversal of Dopamine Transport Science, September 28, 2001; 293(5539): 2465 - 2470. [Abstract] [Full Text] [PDF]
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