The Journal of Neuroscience, November 15, 2002, 22(22):9841-9849
Dopamine-Dependent Desensitization of Dopaminergic Signaling in
the Developing Mouse Striatum
Douglas S.
Kim1,
Glenda
J.
Froelick2, and
Richard D.
Palmiter1, 2, 3
1 Molecular and Cellular Biology Program,
2 Howard Hughes Medical Institute, and
3 Department of Biochemistry, University of Washington,
Seattle, Washington 98195-7370
The dynamics of dopamine receptor signaling efficacy were
characterized in developing mice by measuring striatal c-Fos expression after dopaminergic agonist treatment at postnatal day 4 (P4) to P18.
Control mice and mutant mice, in which dopamine production is
inactivated in dopaminergic neurons by gene targeting, were treated
with saline; a synthetic dopamine precursor,
L-3,4-dihydroxyphenylalanine (L-DOPA) methyl
ester; a direct dopamine D1 receptor agonist, N-allyl-SKF 38393; or a dopamine reuptake
inhibitor, cocaine. L-DOPA methyl ester treatment failed to
induce striatal c-Fos immunoreactivity in control and mutant mice
deficient in dopamine production at P4 and P6 compared with saline
treatment. However, at P10 through P18 it induced abundant c-Fos
expression in mutants. At these later stages, c-Fos expression remained
at basal levels in control mice after L-DOPA methyl ester
treatment. Control and mutant mice responded to D1 receptor
agonist administration to a similar degree at P4 and P6, but the
responses were greatly enhanced in mutants at later stages. Cocaine
treatment elicited expression in control mice at P10 through P18 but
not at P4 and P6. Mutant mice were largely unresponsive to cocaine
treatment. The results suggest that striatal dopamine receptors are
capable of transducing extracellular signals at P4 and P6, but
dopaminergic neurotransmission begins thereafter. Dopaminoceptive
neurons appear to reduce their sensitivity to dopamine as dopaminergic
terminals innervate the striatum and functional neurotransmission begins.
Key words:
aromatic L-amino acid decarboxylase; c-Fos; cocaine; D1 receptor; development; dopamine; dopamine-deficient; L-DOPA; mouse; µ-opioid receptor; N-allyl-SKF 38393; postnatal; striatum; tyrosine
hydroxylase
Copyright © 2002 Society for Neuroscience 0270-6474/02/22229841-09$05.00/0