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This Article Full Text Full Text (PDF) All Versions of this Article: 96/6/2877    most recent 00664.2006v1 Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (6) Citing Articles via Google Scholar Google Scholar Articles by Hernández, A. Articles by Aceves, J. Search for Related Content PubMed PubMed Citation Articles by Hernández, A. Articles by Aceves, J.

Control of the Subthalamic Innervation of the Rat Globus Pallidus by D_2/3 and D₄ Dopamine Receptors

¹Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y Estudios Avanzados; ²Departamento de Biofísica, Instituto de Fisiología Celular; and ³Neurociencias, Facultad de Estudios Superiores-Iztacala, Universidad Nacional Autónoma de México, Federal District, Mexico City, Mexico

Submitted 26 June 2006; accepted in final form 3 August 2006

The effects of activating dopaminergic D_2/3 and D₄ receptors during activation of the subthalamic projection to the globus pallidus (GP) were explored in rat brain slices using the whole cell patch-clamp technique. Byocitin labeling and both orthodromic and antidromic activation demonstrated the integrity of some subthalamopallidal connections in in vitro parasagittal brain slices. Excitatory postsynaptic currents (EPSCs) that could be blocked by CNQX and AP5 were evoked onto pallidal neurons by local field stimulation of the subthalamopallidal pathway in the presence of bicuculline. Bath application of dopamine and quinpirole, a dopaminergic D₂-class receptor agonist, reduced evoked EPSCs by about 35%. This effect was only partially blocked by sulpiride, a D_2/3 receptor antagonist. The sulpiride-sensitive reduction of the subthalamopallidal EPSC was associated with an increase in the paired-pulse ratio (PPR) and a reduction in the frequency but not the mean amplitude of spontaneous EPSCs (sEPSCs), indicative of a presynaptic site of action, which was confirmed by variance–mean analysis. The sulpiride-resistant EPSC reduction was mimicked by PD 168,077 and blocked by L-745,870, selective D₄ receptor agonist and antagonist, respectively, suggesting the involvement of D₄ receptors. The reduction of EPSCs produced by PD 168,077 was not accompanied by changes in PPR or the frequency of sEPSCs; however, it was accompanied by a reduction in mean sEPSC amplitude, indicative of a postsynaptic site of action. These results show that dopamine modulates subthalamopallidal excitation by presynaptic D_2/3 and postsynaptic D₄ receptors. The importance of this modulation is discussed.

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