scholarly journals Endogenous GABA and Glutamate Finely Tune the Bursting of Olfactory Bulb External Tufted Cells

2007 ◽  
Vol 98 (2) ◽  
pp. 1052-1056 ◽  
Author(s):  
Abdallah Hayar ◽  
Matthew Ennis
Keyword(s):  
Olfactory Bulb ◽  
Glutamate Receptors ◽  
Synaptic Input ◽  
Aminobutyric Acid ◽  
Ionotropic Glutamate Receptors ◽  
Endogenous Gaba ◽  
Shunting Effect ◽  
Tufted Cells ◽  
Olfactory Bulb Slices ◽  
Spike Bursts

In rat olfactory bulb slices, external tufted (ET) cells spontaneously generate spike bursts. Although ET cell bursting is intrinsically generated, its strength and precise timing may be regulated by synaptic input. We tested this hypothesis by analyzing whether the burst properties are modulated by activation of ionotropic γ-aminobutyric acid (GABA) and glutamate receptors. Blocking GABAA receptors increased—whereas blocking ionotropic glutamate receptors decreased—the number of spikes/burst without changing the interburst frequency. The GABAA agonist (isoguvacine, 10 μM) completely inhibited bursting or reduced the number of spikes/burst, suggesting a shunting effect. These findings indicate that the properties of ET cell spontaneous bursting are differentially controlled by GABAergic and glutamatergic fast synaptic transmission. We suggest that ET cell excitatory and inhibitory inputs may be encoded as a change in the pattern of spike bursting in ET cells, which together with mitral/tufted cells constitute the output circuit of the olfactory bulb.

Electrophysiology of Interneurons in the Glomerular Layer of the Rat Olfactory Bulb

2001 ◽  
Vol 86 (4) ◽  
pp. 1899-1907 ◽  
Author(s):  
A. Rory McQuiston ◽  
Lawrence C. Katz
Keyword(s):  
Olfactory Bulb ◽  
Action Potentials ◽  
Neuronal Morphology ◽  
Bursting Neurons ◽  
Whole Cell Patch Clamp ◽  
Physiological Properties ◽  
Receptor Neurons ◽  
Tufted Cells ◽  
Olfactory Bulb Slices ◽  
Channel Dependent

In the mammalian olfactory bulb, glomeruli are surrounded by a heterogeneous population of interneurons called juxtaglomerular neurons. As they receive direct input from olfactory receptor neurons and connect with mitral cells, they are involved in the initial stages of olfactory information processing, but little is known about their detailed physiological properties. Using whole cell patch-clamp techniques, we recorded from juxtaglomerular neurons in rat olfactory bulb slices. Based on their response to depolarizing pulses, juxtaglomerular neurons could be divided into two physiological classes: bursting and standard firing. When depolarized, the standard firing neurons exhibited a range of responses: accommodating, nonaccommodating, irregular firing, and delayed to firing patterns of action potentials. Although the firing pattern was not rigorously predictive of a particular neuronal morphology, most short axon cells fired accommodating trains of action potentials, while most delayed to firing cells were external tufted cells. In contrast to the standard firing neurons, bursting neurons produced a calcium-channel-dependent low-threshold spike when depolarized either by current injection or by spontaneous or evoked postsynaptic potentials. Bursting neurons also could oscillate spontaneously. Most bursting cells were either periglomerular cells or external tufted cells. Based on their mode of firing and placement in the bulb circuit, these bursting cells are well situated to drive synchronous oscillations in the olfactory bulb.

Heterogeneity of γ-aminobutyric acid type A receptors in mitral and tufted cells of the rat main olfactory bulb

2005 ◽  
Vol 484 (1) ◽  
pp. 121-131 ◽  
Author(s):  
Patrizia Panzanelli ◽  
Alice-Zaira Perazzini ◽  
Jean-Marc Fritschy ◽  
Marco Sassoè-Pognetto
Keyword(s):  
Olfactory Bulb ◽  
Type A ◽  
Aminobutyric Acid ◽  
Main Olfactory Bulb ◽  
Acid Type ◽  
Tufted Cells

scholarly journals Metabotropic glutamate receptors promote disinhibition of olfactory bulb glomeruli that scales with input strength

2015 ◽  
Vol 113 (6) ◽  
pp. 1907-1920 ◽  
Author(s):  
Joseph D. Zak ◽  
Jennifer D. Whitesell ◽  
Nathan E. Schoppa
Keyword(s):  
Olfactory Bulb ◽  
Glutamate Receptors ◽  
Metabotropic Glutamate Receptors ◽  
Gaba Release ◽  
Inhibitory Synapses ◽  
Metabotropic Glutamate ◽  
Olfactory Bulb Slices ◽  
Odor Signals ◽  
Input Strength ◽  
Mediated Reduction

Increasing evidence indicates that the neural circuitry within glomeruli of the olfactory bulb plays a major role in affecting information flow between olfactory sensory neurons (OSNs) and output mitral cells (MCs). Glutamatergic external tufted (ET) cells, located at glomeruli, can act as intermediary cells in excitation between OSNs and MCs, whereas activation of MCs by OSNs is, in turn, suppressed by inhibitory synapses onto ET cells. In this study, we used patch-clamp recordings in rat olfactory bulb slices to examine the function of metabotropic glutamate receptors (mGluRs) in altering these glomerular signaling mechanisms. We found that activation of group II mGluRs profoundly reduced inhibition onto ET cells evoked by OSN stimulation. The mGluRs that mediated disinhibition were located on presynaptic GABAergic periglomerular cells and appeared to be activated by glutamate transients derived from dendrites in glomeruli. In terms of glomerular output, the mGluR-mediated reduction in GABA release led to a robust increase in the number of action potentials evoked by OSN stimulation in both ET cells and MCs. Importantly, however, the enhanced excitation was specific to when a glomerulus was strongly activated by OSN inputs. By being selective for strong vs. weak glomerular activation, mGluR-mediated disinhibition provides a mechanism to enhance the contrast in odor signals that activate OSN inputs into a single glomerulus at varying intensities.

Glycine agonism in ionotropic glutamate receptors

2021 ◽  
pp. 108631
Author(s):  
David Stroebel ◽  
Laetitia Mony ◽  
Pierre Paoletti
Keyword(s):  
Glutamate Receptors ◽  
Ionotropic Glutamate Receptors
Sign in / Sign up

Export Citation Format

Share Document