TY - JOUR
T1 - Inhibitory control of the GABAergic transmission in the rat neostriatum by D2 dopamine receptors
AU - Delgado, A.
AU - Sierra, A.
AU - Querejeta, E.
AU - Valdiosera, R. F.
AU - Aceves, J.
N1 - Funding Information:
The study was supported by grants (3539P-N9607 and 1245-N9203) from the Consejo Nacional de Ciencia y Tecnologia (CONACYT) de México. A.D. was a CONACYT fellow.
PY - 1999/12
Y1 - 1999/12
N2 - The aim of the study was to determine the role of dopamine on the GABAergic input to striatal projection neurons. Accordingly, the effect of the activation of dopamine D2-like receptors on GABA-mediated depolarizing postsynaptic potentials evoked in striatal slices by local stimulation was studied. Conventional intracellular recording techniques were used to record the synaptic responses. The experiments were done in the presence of 6-cyano-7-nitroquinoxaline-2,3-dione (20μM) and (±)-2-amino-5-phosphonovaleric acid (40μM) to block the participation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate/kainate and N-methyl-D-aspartate receptors in the synaptic response. The GABAergic nature of the response was assessed by its potentiation by pentobarbital (50μM) and by its elimination by bicuculline or picrotoxin. At 100nM, a concentration already maximal, dopamine inhibited by 55% the GABAergic synaptic response. The inhibitory effect was totally blocked by the selective antagonist of D2-like receptors, sulpiride (100nM). The dopamine inhibition was observed only in one-third of the studied neurons and was concentration dependent (IC50=14nM). The inhibition was not associated with changes in the input resistance or any other membrane property. In addition, dopamine (50nM) reduced the frequency but not the amplitude of spontaneous, bicuculline-sensitive depolarizing postsynaptic potentials. The D2-like receptor agonist quinpirole also dose-dependently (IC50=10nM) inhibited the GABAergic synaptic response. As with dopamine, the inhibition did not change the membrane properties of the studied neurons. In addition, the quinpirole induced inhibition of the GABA response was accompanied by increased paired-pulse facilitation.The results indicate that D2-like receptors located on intrinsic GABAergic terminals in the rat striatum exert an inhibitory control of the GABAergic input to striatal projection neurons. The dopaminergic effect would be translated in facilitation of the firing of the neurons upon the arrival of the cortical input. Copyright (C) 1999 IBRO.
AB - The aim of the study was to determine the role of dopamine on the GABAergic input to striatal projection neurons. Accordingly, the effect of the activation of dopamine D2-like receptors on GABA-mediated depolarizing postsynaptic potentials evoked in striatal slices by local stimulation was studied. Conventional intracellular recording techniques were used to record the synaptic responses. The experiments were done in the presence of 6-cyano-7-nitroquinoxaline-2,3-dione (20μM) and (±)-2-amino-5-phosphonovaleric acid (40μM) to block the participation of α-amino-3-hydroxy-5-methyl-4-isoxazolepropionate/kainate and N-methyl-D-aspartate receptors in the synaptic response. The GABAergic nature of the response was assessed by its potentiation by pentobarbital (50μM) and by its elimination by bicuculline or picrotoxin. At 100nM, a concentration already maximal, dopamine inhibited by 55% the GABAergic synaptic response. The inhibitory effect was totally blocked by the selective antagonist of D2-like receptors, sulpiride (100nM). The dopamine inhibition was observed only in one-third of the studied neurons and was concentration dependent (IC50=14nM). The inhibition was not associated with changes in the input resistance or any other membrane property. In addition, dopamine (50nM) reduced the frequency but not the amplitude of spontaneous, bicuculline-sensitive depolarizing postsynaptic potentials. The D2-like receptor agonist quinpirole also dose-dependently (IC50=10nM) inhibited the GABAergic synaptic response. As with dopamine, the inhibition did not change the membrane properties of the studied neurons. In addition, the quinpirole induced inhibition of the GABA response was accompanied by increased paired-pulse facilitation.The results indicate that D2-like receptors located on intrinsic GABAergic terminals in the rat striatum exert an inhibitory control of the GABAergic input to striatal projection neurons. The dopaminergic effect would be translated in facilitation of the firing of the neurons upon the arrival of the cortical input. Copyright (C) 1999 IBRO.
KW - Basal ganglia
KW - Corticostriatal transmission
KW - Feedforward inhibition
KW - GABA interneurons
KW - Striatal projection neurons
UR - http://www.scopus.com/inward/record.url?scp=0033404534&partnerID=8YFLogxK
U2 - 10.1016/S0306-4522(99)00495-9
DO - 10.1016/S0306-4522(99)00495-9
M3 - Artículo
SN - 0306-4522
VL - 95
SP - 1043
EP - 1048
JO - Neuroscience
JF - Neuroscience
IS - 4
ER -