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Dopamine receptor regulation of Ca 2+ levels in individual isolated nerve terminals from rat striatum: comparison of presynaptic D 1 ‐like and D 2 ‐like receptors
Author(s) -
Wu Jianlin,
Dougherty John. J.,
Nichols Robert A.
Publication year - 2006
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.2006.03901.x
Subject(s) - striatum , neuroscience , dopamine , receptor , dopamine receptor d2 , dopamine receptor , d1 like receptor , dopamine receptor d1 , chemistry , biology , biochemistry
We have directly observed the effects of activating presynaptic D 1 ‐like and D 2 ‐like dopamine receptors on Ca 2+ levels in isolated nerve terminals (synaptosomes) from rat striatum. R‐(+)‐SKF81297, a selective D 1 ‐like receptor agonist, and (–)‐quinpirole, a selective D 2 ‐like receptor agonist, induced increases in Ca 2+ levels in different subsets of individual striatal synaptosomes. The SKF81297‐ and quinpirole‐induced effects were blocked by R‐(+)‐SCH23390, a D 1 ‐like receptor antagonist, and (–)‐sulpiride, a D 2 ‐like receptor antagonist, respectively. SKF81297‐ or quinpirole‐induced Ca 2+ increases were inhibited following blockade of voltage‐gated calcium channels or sodium channels. In a larger subset of synaptosomes, quinpirole decreased baseline Ca 2+ . Quinpirole also inhibited veratridine‐induced increases in intrasynaptosomal Ca 2+ level. Immunostaining confirmed the presynaptic expression of D 1 , D 5 , D 2 and D 3 receptors, but not D 4 receptors. The array of neurotransmitter phenotypes of the striatal nerve endings expressing D 1 , D 5 , D 2 or D 3 varied for each receptor subtype. These results suggest that presynaptic D 1 ‐like and D 2 ‐like receptors induce increases in Ca 2+ levels in different subsets of nerve terminals via Na + channel‐mediated membrane depolarization, which, in turn, induces the opening of voltage‐gated calcium channels. D 2 ‐like receptors also reduce nerve terminal Ca 2+ in a different but larger subset of synaptosomes, consistent with the predominant presynaptic action of dopamine in the striatum being inhibitory.