Volume 17, Number 21,
Issue of November 1, 1997
pp. 8498-8505
Copyright ©1997 Society for Neuroscience
Substantia Nigra D1 Receptors and Stimulation of
Striatal Cholinergic Interneurons by Dopamine: A Proposed Circuit
Mechanism
Received June 10, 1997; revised Aug. 4, 1997; accepted Aug. 13, 1997.
Elizabeth D. Abercrombie and
Peter DeBoer
Center for Molecular and Behavioral Neuroscience, Rutgers
University, Newark, New Jersey 07102
Dopamine release can regulate striatal acetylcholine efflux
in vivo through at least two receptor mechanisms: (1)
direct inhibition by dopamine D2 receptors on the
cholinergic neurons, and (2) excitation initiated by dopamine
D1 receptors. The neuroanatomical locus of the latter
population of D1 receptors and the pathway(s) involved in
the expression of their influence are controversial issues. We have
tested the hypothesis that D1 receptors in substantia nigra
pars reticulata are involved in the excitatory component of
dopaminergic actions on striatal acetylcholine output. In
vivo microdialysis was used in awake rats. Infusion of the
selective D1 receptor agonist
R(+)-1-Phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine-7,8-diol (SKF 38393) hydrochloride into pars reticulata of substantia nigra elicited a significant increase in striatal acetylcholine efflux. Likewise, D-amphetamine applied into pars reticulata of
substantia nigra by reverse dialysis produced an elevation in
acetylcholine output measured at a second microdialysis probe in the
striatum. Application of D-amphetamine in the striatum by
reverse dialysis elicited a decrease in striatal acetylcholine efflux
that could be reversed subsequently by local application of
D-amphetamine in substantia nigra pars reticulata. A 2 mg/kg intraperitoneal dose of D-amphetamine, which has no
net effect on striatal acetylcholine output under control conditions,
elicited a significant decrease in acetylcholine efflux when the
D1 receptor antagonist
R(+)-7-Chloro-8-hydroxy-3-methyl-1-phenyl-2,3,4,5-tetrahydro-1H-3-benzazepine (SCH 23390) hydrochloride was applied simultaneously via a second microdialysis probe in substantia nigra pars reticulata. Thus, an
excitatory D1-mediated influence on striatal acetylcholine output is initiated in substantia nigra pars reticulata, and this influence contributes to the effects of indirect dopaminergic agonists
such as D-amphetamine on striatal acetylcholine efflux. These results indicate an important role of somatodendritic dopamine release, in addition to nerve terminal dopamine release, in the regulation of activity in basal ganglia circuits.
Key words:
acetylcholine;
dopamine;
GABA;
substantia nigra;
striatum;
D-amphetamine;
dopamine D1 receptor;
in vivo microdialysis