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Dopamine is a critical modulator of striatal function; its absence produces Parkinson's disease. Most cellular actions of dopamine are still unknown. This work describes the presynaptic actions of dopaminergic receptor agonists on GABAergic transmission between neostriatal projection neurons. Axon collaterals interconnect projection neurons, the main axons(More)
Here we have explored whether dopamine is able to modulate the release of gamma-aminobutyric acid (GABA) from striatal terminals to substantia nigra pars reticulata, entopeduncular nucleus, globus pallidus and caudate-putamen. The type of dopamine receptors involved was assessed by the blocking effect of either SCH 23390 (D1 antagonist) or (-)-sulpiride (D2(More)
We analysed the expression of dopamine receptor subtypes in the subthalamic nucleus by means of reverse transcriptase-polymerase chain reaction. We also studied, using autoradiography, all pharmacologically characterized dopamine receptors in four subregions of the subthalamic nucleus. For comparison, dopamine receptor subtypes were also evaluated in brain(More)
Intracellular spontaneous activity was recorded in neostriatal slices from rats with 6-hydroxydopamine-induced lesion of the left nigrostriatal dopaminergic system. Recordings were made at different times after denervation. Dopaminergic denervation caused the appearance of spontaneous synaptic potentials, which were present even after 8 months. The results(More)
1. Intracellular recordings from neostriatal neurons in an in vitro slice preparation of the rat brain were used to analyze the pharmacological sensitivity of the action potential (AP) repolarization and the afterhyperpolarization (AHP) that follows a single action potential. The interspike voltage trajectory and the AHP could be divided into two main(More)
We studied the interactions between glutamate and dopamine in the pars reticulata of the substantia nigra by using microdialysis in unanaesthetized rats. Increased extracellular levels of glutamate in the pars reticulata were obtained by microinjecting the muscarinic agonist carbachol into the ipsilateral subthalamic nucleus. The increase of glutamate(More)
The effect of 5-hydroxytryptamine on the spontaneous activity of neurons of the subthalamic nucleus was examined by recording the extracellular unitary activity in an in vitro slice preparation. The most frequent response to 5-hydroxytryptamine (84% of 57 neurons tested) was an increase (twofold of basal at 10 microM) of the discharge frequency. The EC50(More)
Because activation of D2 dopamine receptors inhibits gamma-aminobutyric acid (GABA) release from intrapallidal nerve terminals, we measured the effects of modifiers of dopamine D2 receptors on the firing rate of single neurons in the globus pallidus (GP) of the anesthetized rat. The predominant effect of intrapallidal administration of the selective D2(More)
Attempting to better understand the role of the dopaminergic innervation in the rat globus pallidus, we examined here whether or not endogenous dopamine modulates the release of [3H]GABA in superfused pallidal slices. The superfusion medium contained elevated (15 mM) potassium. The release of endogenous dopamine was induced by the dopamine releaser drug,(More)
GABA(B) receptors decrease the release of GABA from the striatal terminals within the pars reticulata of the substantia nigra by opposing the increase in the release caused by dopamine D₁ receptors. The dopamine D₁ receptors also increase the release of glutamate from subthalamic terminals in the pars reticulata. Because GABA(B) receptors decrease the(More)