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Regulatory Effects of D2 Receptors in the Ventral Tegmental Area on the Mesocorticolimbic Dopaminergic Pathway
Author(s) -
Chen Nancy N. H.,
Pan Wynn H. T.
Publication year - 2000
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 - 10.1046/j.1471-4159.2000.0742576.x
Subject(s) - ventral tegmental area , dopaminergic , neuroscience , receptor , dopamine receptor , dopaminergic pathways , dopamine , biology , chemistry , biochemistry
To investigate the regulatory effects of somatodendritic D2 receptors on the terminal’s extracellular dopamine (DA) concentration, a D2 antagonist (eticlopride) was infused directly into the ventral tegmental area via a microdialysis probe in chloral hydrate‐anesthetized rats. Extracellular DA changes in both the nucleus accumbens (N ACC) and the medial prefrontal cortex (mPFC) were monitored. Infusion of 10.0 f M eticlopride had no effect on DA in the mPFC (110.2 ± 10.0% of baseline) but significantly increased DA in the N ACC (150.1 ± 11.7%). Infusion of a higher dose of eticlopride (100.0 or 1,000.0 f M ) significantly augmented the DA in the mPFC (121.1 ± 7.6 and 180.7 ± 25.8%, respectively) but surprisingly had no effect on DA in the N ACC (111.5 ± 7.3 and 104.1 ± 8.7%, respectively). To further investigate whether the bluntness of DA increase in the N ACC was due to DA receptor activation in the mPFC, eticlopride or SCH23390 was infused into the mPFC prior to and during intrategmental eticlopride infusion, and the change of DA in the N ACC was simultaneously monitored. During intra‐mPFC 1.0 n M eticlopride infusion but not during 10.0 n M SCH23390 administration (95.5 ± 6.1%), intrategmental 1,000.0 f M eticlopride infusion could further elevate DA in the N ACC (130.0 ± 4.6%). Our results indicated that (1) the mesolimbic and the mesocortical pathways were under tonic inhibition by somatodendritic D2 receptors; (2) the DA concentration in the N ACC first increased and then returned to baseline while the intrategmental infusion dose of eticlopride increased; and (3) the bluntness of DA increase in the N ACC resulted from the D2 receptor activation in the mPFC.