Related Experiment Video
Updated: May 19, 2026
05:02
Using Unidirectional Rotations to Improve Vestibular System Asymmetry in Patients with Vestibular Dysfunction
Published on: August 30, 2019
Presynaptic GABA(B) receptors decrease neurotransmitter release in vestibular nuclei neurons during vestibular
M Shao1, R Reddaway, J C Hirsch
1Department of Anatomy and Regenerative Biology, George Washington University School of Medicine, Washington, DC 20037, United States.
Neuroscience
|August 9, 2012
Summary
This study reveals how GABA(B) receptors on nerve terminals, not cell surfaces, aid vestibular compensation after injury. Differences in receptor function were observed between compensating and uncompensated chickens.
Area of Science:
- Neuroscience
- Vestibular System Research
- Receptor Pharmacology
Background:
- Unilateral vestibular damage causes balance and eye movement deficits.
- Vestibular compensation mechanisms are not fully understood.
- GABA(B) receptor activation is implicated in recovery, but its precise action site is unknown.
Purpose of the Study:
- To investigate the presynaptic and postsynaptic roles of GABA(B) receptors in vestibular nuclei neurons after unilateral vestibular ganglionectomy (UVG).
- To correlate GABA(B) receptor subunit-2 (GABA(B)R2) expression with receptor function in different stages of vestibular compensation.
Main Methods:
- Patch-clamp recordings were used to measure postsynaptic currents and miniature events in principal cells of the tangential nucleus in control and UVG-operated chickens.
- Immunolabeling and confocal imaging identified GABA(B)R2 localization in relation to synaptic markers.
- Baclofen, a GABA(B) agonist, was applied to assess receptor activity.
Main Results:
- Baclofen did not induce postsynaptic currents, indicating minimal postsynaptic GABA(B) receptor activity.
- Baclofen reduced miniature excitatory and inhibitory postsynaptic currents, confirming functional presynaptic GABA(B) receptors.
- Changes in GABA(B)R2 expression and localization in presynaptic terminals were observed, differing between compensating and uncompensated states.
Conclusions:
- Presynaptic GABA(B) receptors play a crucial role in vestibular compensation following UVG.
- GABA(B) autoreceptors on vestibular nuclei neurons and GABA(B) heteroreceptors on glutamatergic terminals are involved in early compensation and recovery failure, respectively.
Related Concept Videos
01:29The Vestibular System
The vestibular system is a set of inner ear structures that provide a sense of balance and spatial orientation. This system is comprised of structures within the labyrinth of the inner ear, including the cochlea and two otolith organs—the utricle and saccule. The labyrinth also contains three semicircular canals—superior, posterior, and horizontal—that are oriented on different planes.
01:15Equilibrium and Balance
The inner ear assumes dual functionalities of auditory perception and equilibrium maintenance. The vestibule is the organ responsible for balance. This organ contains mechanoreceptors, specifically hair cells, endowed with stereocilia, which aid in deciphering information regarding the position and motion of our heads. Two intrinsic components, the utricle and saccule, help perceive head position, while the semicircular canals track head movement. Neurological messages initiated in the...
01:29Excitatory and Inhibitory Effects of Neurotransmitters
When an action potential reaches the presynaptic axon terminal, it releases neurotransmitters from the neuron into the synaptic cleft at a chemical synapse. The released neurotransmitter can be excitatory or inhibitory. The critical criteria commonly used to determine whether a molecule is a neurotransmitter at a chemical synapse are the molecule's presence in the presynaptic neuron. Second, its release is in response to strong presynaptic depolarization. And lastly, the presence of specific...
01:30Ligand-Gated Ion Channel Receptor: Gating Mechanism
Ligand-gated ion channels are transmembrane proteins that play a vital role in intercellular communication and functions of the nervous system. They allow the influx of ions across the membrane once the neurotransmitter binds, allowing the subsequent transmission of electrical excitation across the neurons. Other ligand-gated ion channels, like the γ-aminobutyric acid (GABA) receptor, permit anions like chloride into the cells on the binding of the GABA molecule. Their entry into the cell...
01:28Integration of Synaptic Events
Synaptic integration mainly includes the summation of graded potentials. Graded potentials, regardless of their type, cause subtle alterations in membrane voltage, resulting in either depolarization or hyperpolarization. These incremental changes, when combined or summed, can propel the neuron toward its threshold. Consider, for example, a membrane experiencing a +15 mV shift, causing it to depolarize from -70 mV to -55 mV. In this scenario, graded potentials govern the membrane's ability to...
01:22Pathophysiology of Vomiting
Vomiting is a complex physiological response to expel harmful or irritating substances from the body. It's a defensive mechanism triggered by stimuli like poisons, microbial toxins, cytotoxic drugs, and mechanical abdominal distension. The process is centrally coordinated by the vomiting (or emetic) center located in the medulla of the brainstem. This area, rich in muscarinic M1, histamine H1, neurokinin 1 (NK1), and serotonin 5-HT3 receptors, coordinates the act of vomiting through interaction...