scholarly journals Heterogeneity in Use-Dependent Depression of Inhibitory Postsynaptic Potentials in the Rat Neostriatum In Vitro

1997 ◽  
Vol 77 (1) ◽  
pp. 427-434 ◽  
Author(s):  
Gabriele Radnikow ◽  
Jutta Rohrbacher ◽  
Ulrich Misgeld
Keyword(s):  
Aminobutyric Acid ◽  
Medium Spiny Neurons ◽  
Stimulus Interval ◽  
Postsynaptic Potentials ◽  
Inhibitory Postsynaptic Potentials ◽  
Spiny Neurons ◽  
Neostriatal Slices ◽  
Minimal Stimulation ◽  
Paired Pulse Depression

Radnikow, Gabriele, Jutta Rohrbacher, and Ulrich Misgeld. Heterogeneity in use-dependent depression of inhibitory postsynaptic potentials in the rat neostriatum in vitro. J. Neurophysiol. 77: 427–434, 1997. “Minimal stimulation” was applied to evoke responses in an “all-or-none” fashion in presumed medium spiny neurons of rat neostriatal slices in the presence of antagonists for glutamatergic excitation. For comparison, responses were evoked in the same cells by compound stimulation. Bicuculline (30 μM) blocked responses evoked by minimal stimulation, indicating that they were γ-aminobutyric acid-A (GABAA)-receptor-mediated inhibitory postsynaptic potentials (IPSPs), whereas responses evoked by compound stimulation were only reduced in amplitude. Likewise, R(−)baclofen (1–20 μM) blocked IPSPs evoked by minimal stimulation in all but one cell. On the contrary, responses evoked by compound stimulation were always reduced in amplitude but never blocked. Paired-pulse depression (PPD) of averaged responses to minimal and compound stimulation was observed at a stimulus interval of 300 ms. The GABAB receptor antagonist CGP55845A (0.5 μM) had no effect on PPD evoked by compound stimulation but abolished PPD evoked by minimal stimulation. In a second set of experiments, the two stimulation paradigms were used to evoke responses in neostriatal slices continuously bathed in R(−)baclofen (10–20 μM). In R(−)baclofen a strong PPD was evoked by minimal and by compound stimulation. The amplitude of the response to compound stimulation increased on application of CGP55845A (0.5 μM). At the same time, PPD evoked by compound stimulation decreased. On the contrary, IPSP amplitude and PPD evoked by minimal stimulation remained unchanged. We conclude that two types of GABAergic terminals exist in the rat neostriatum, only one of which is regulated by GABAB receptors. However, the other class of terminals, not regulated by GABAB receptors, displays a much more pronounced PPD.

Different Inhibitory Inputs Onto Neostriatal Projection Neurons as Revealed by Field Stimulation

2005 ◽  
Vol 93 (2) ◽  
pp. 1119-1126 ◽  
Author(s):  
Fatuel Tecuapetla ◽  
Luis Carrillo-Reid ◽  
Jaime N. Guzmán ◽  
Elvira Galarraga ◽  
José Bargas
Keyword(s):  
Channel Blocker ◽  
Inhibitory Synapses ◽  
Projection Neurons ◽  
Medium Spiny Neurons ◽  
Field Stimulation ◽  
Paired Pulse ◽  
Postsynaptic Currents ◽  
Spiny Neurons ◽  
Short Time ◽  
Paired Pulse Depression

This work investigated if diverse properties could be ascribed to evoked inhibitory postsynaptic currents (IPSCs) recorded on rat neostriatal neurons when field stimulation was delivered at two different locations: the globus pallidus (GP) and the neostriatum (NS). Previous work stated that stimulation in the GP could antidromically excite projection axons from medium spiny neurons. This maneuver would predominantly activate the inhibitory synapses that interconnect spiny cells. In contrast, intrastriatal stimulation would preferentially activate inhibitory synapses provided by interneurons. This study shows that, in fact, intensity-amplitude experiments are able to reveal different properties for IPSCs evoked from these two locations (GP and NS). In addition, while all IPSCs evoked from the GP were always sensitive to ω-conotoxin GVIA (CaV2.22.2 or N-channel blocker), one-half of the inhibition evoked from the NS exhibited little sensitivity to ω-conotoxin GVIA. Characteristically, all ω-conotoxin GVIA–insensitive IPSCs exhibited strong paired pulse depression, whereas ω-conotoxin GVIA–sensitive IPSCs evoked from either the GP or the NS could exhibit short-time depression or facilitation. ω-Agatoxin TK (CaV2.12.1+ or P/Q-channel blocker) blocked IPSCs evoked from both locations. Therefore 1) distinct inhibitory inputs onto projection neostriatal cells can be differentially stimulated with field electrodes; 2) N-type Ca2+ channels are not equally expressed in inhibitory terminals activated in the NS; and 3) synapses that interconnect spiny neurons use both N- and P/Q-type Ca2+ channels.

scholarly journals Neurotransmitters in the Mammalian Striatum: Neuronal Circuits and Heterogeneity

1987 ◽  
Vol 14 (S3) ◽  
pp. 386-394 ◽  
Author(s):  
K. Semba ◽  
H.C. Fibiger ◽  
S.R. Vincent
Keyword(s):  
Substantia Nigra ◽  
Aminobutyric Acid ◽  
Projection Neurons ◽  
Medium Spiny Neurons ◽  
Synaptic Connections ◽  
Spiny Neurons ◽  
Striatal Projection Neurons ◽  
Matrix Organization ◽  
Output Neurons ◽  
Striatal Interneurons

ABSTRACT:The major input and output pathways of the mammalian striatum have been well established. Recent studies have identified a number of neurotransmitters used by these pathways as well as by striatal interneurons, and have begun to unravel their synaptic connections. The major output neurons have been identified as medium spiny neurons which contain ɣ-aminobutyric acid (GABA), endogeneous opioids, and substance P. These neurons project to the pallidum and substantia nigra in a topographic and probably chemically organized manner. The major striatal afferents from the cerebral cortex, thalamus, and substantia nigra terminate, at least in part, on these striatal projection neurons. Striatal interneurons contain acetylcholine, GABA, and somatostatin plus neuropeptide Y, and appear to synapse on striatal projection neurons. In recent years, much activity has been directed to the neurochemical and hodological heterogeneities which occur at a macroscopic level in the striatum. This has led to the concept of a patch-matrix organization in the striatum.

Inhibitory Interactions Between Ferret Thalamic Reticular Neurons

2002 ◽  
Vol 87 (5) ◽  
pp. 2571-2576 ◽  
Author(s):  
Yousheng Shu ◽  
David A. McCormick
Keyword(s):  
Reversal Potential ◽  
Thalamic Reticular Nucleus ◽  
Reticular Nucleus ◽  
Inhibitory Input ◽  
Inhibitory Interaction ◽  
Postsynaptic Potentials ◽  
Inhibitory Postsynaptic Potentials ◽  
Reticular Neurons ◽  
Inhibitory Interactions

The thalamic reticular nucleus (nRt) provides an important inhibitory input to thalamic relay nuclei and is central in the generation of both normal and abnormal thalamocortical activities. Although local inhibitory interactions between these neurons may play an important role in controlling thalamocortical activities, the physiological features of this interaction have not been fully investigated. Here we sought to establish the nature of inhibitory interaction between nRt neurons with intracellular and extracellular recordings in slices of ferret nRt maintained in vitro. In many nRt neurons, intracellular recordings revealed spontaneous inhibitory postsynaptic potentials (IPSPs). In addition, the local excitation of nRt cells with glutamate led to the generation of IPSPs in the intracellularly recorded nRt neuron. These evoked IPSPs exhibited an average reversal potential of −72 mV and could be blocked by picrotoxin, a GABAA-receptor antagonist. These results indicate that nRt neurons interact locally through the activation of GABAA receptor-mediated inhibitory postsynaptic potentials. This lateral inhibition may play an important role in controlling the responsiveness of these cells to cortical and thalamic excitatory inputs in both normal and abnormal thalamocortical function.

Valproate enhances inhibitory postsynaptic potentials in hippocampal neurons in vitro

1987 ◽  
Vol 435 (1-2) ◽  
pp. 213-219 ◽  
Author(s):  
Uli Preisendörfer ◽  
Marc L. Zeise ◽  
Manfred R. Klee
Keyword(s):  
Hippocampal Neurons ◽  
Postsynaptic Potentials ◽  
Inhibitory Postsynaptic Potentials
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