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Updated: Jul 12, 2025
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Inducing Plasticity of Astrocytic Receptors by Manipulation of Neuronal Firing Rates
Published on: March 20, 2014
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Increased astrocytic GLT-1 expression in tripartite synapses is associated with SCI-induced hyperreflexia
Curtis A Benson1,2, Jared F King1,2, Sierra D Kauer1,2
1Department of Neurology and Center for Neuroscience and Regeneration Research, Yale University School of Medicine, New Haven, Connecticut, United States.
Journal of Neurophysiology
|October 25, 2023
Summary
Spinal cord injury (SCI) can cause spasticity and hyperreflexia. This study found that increased astrocyte-neuron connections, specifically involving GLT-1 and PSD-95 proteins, are linked to this condition after SCI.
Area of Science:
- Neuroscience
- Cellular Biology
- Spinal Cord Injury Research
Background:
- Spasticity, a common complication of spinal cord injury (SCI), involves increased muscle tone and stiffness.
- Hyperreflexia, a key sign of spasticity, is characterized by the loss of rate-dependent depression (RDD) in the H-reflex.
- Astrogliosis, associated with SCI, is implicated in hyperexcitability disorders, but its precise role in modulating synaptic transmission in the injured spinal cord remains unclear.
Purpose of the Study:
- To investigate the role of astrocytes in the development of hyperreflexia following spinal cord injury.
- To examine the expression and spatial relationship of glutamate transporter-1 (GLT-1) in astrocytes and postsynaptic density protein 95 (PSD-95) in neurons within the ventral horn.
- To determine if astrocyte-neuron synaptic complexes are associated with SCI-induced hyperreflexia and spasticity.
Main Methods:
- Comparison of animals with and without SCI-induced hyperreflexia and spasticity.
- Analysis of GLT-1 and PSD-95 protein expression and co-localization in the ventral horn (lamina IX) at spinal segments L4-5.
- Electromyogram recordings to assess H-reflex and evoked rate-dependent depression (RDD).
Main Results:
- Four weeks after SCI, animals exhibited a loss of evoked H-reflex RDD, indicating hyperreflexia, compared to uninjured controls.
- A significant increase in GLT-1-PSD-95 tripartite synapses was observed in the ventral spinal cord motor regions of animals with SCI-induced hyperreflexia.
- These findings suggest a correlation between the presence of these specific astrocyte-neuron synaptic complexes and the development of hyperreflexia.
Conclusions:
- Astrocyte-neuron synaptic complexes, marked by GLT-1 and PSD-95, are involved in the synaptic plasticity underlying chronic spasticity after SCI.
- The study highlights the understudied role of astrocytes in SCI-induced H-reflex hyperexcitability.
- These findings offer a novel perspective on synaptic alterations contributing to the progression of SCI-related spasticity.
