Presynaptic control of corticostriatal synapses by endogenous GABA.
Corticostriatal terminals have presynaptic GABA(B) receptors that limit glutamate release, but how these receptors are activated by endogenous GABA released by different types of striatal neurons is still unknown. To address this issue, we used single and paired whole-cell recordings combined with stimulation of corticostriatal fibers in rats and mice. In the presence of opioid, GABA(A), and NK1 receptor antagonists, antidromic stimulation of a population of striatal projection neurons caused suppression of subsequently evoked EPSPs in projection neurons. These effects were larger at intervals of 500 ms than 1 or 2 s, and were fully blocked by the selective GABA(B) receptor antagonist CGP 52432. Bursts of spikes in individual projection neurons were not able to inhibit evoked EPSPs. Similarly, spikes in fast spiking interneurons and low-threshold spike interneurons failed to elicit detectable effects mediated by GABA(B) receptors. Conversely, spikes in individual neurogliaform interneurons suppressed evoked EPSPs, and these effects were blocked by CGP 52432. These results provide the first demonstration of how GABA(B) receptors are activated by endogenous GABA released by striatal neuronal types.
Faculty of Life Sciences, University of Manchester, Manchester M13 9PT, United Kingdom, Laboratorio di Neurofisiologia, Fondazione Santa Lucia, 00143 Rome, Italy, and Department of Psychology, The University of Sheffield, Sheffield S10 2TP, United Kingdom.
Christopher
C
Logie
Vincenza
V
Bagetta
Enrico
E
Bracci
D000818:Animals; D002540:Cerebral Cortex / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D003342:Corpus Striatum / Q000166:cytology / Q000378:metabolism / Q000502:physiology*; D019706:Excitatory Postsynaptic Potentials / Q000187:drug effects; D005260:Female; D018756:GABA Antagonists / Q000494:pharmacology; D007395:Interneurons / Q000187:drug effects / Q000378:metabolism / Q000502:physiology; D051379:Mice; D009292:Narcotic Antagonists / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D013569:Synapses / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
D018756:GABA Antagonists; D009292:Narcotic Antagonists; D005680:gamma-Aminobutyric Acid