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Optogenetic Stimulation of the Auditory Nerve
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Astrocyte Hypertrophy and Microglia Activation in the Rat Auditory Midbrain Is Induced by Electrical Intracochlear
Nicole Rosskothen-Kuhl1, Heika Hildebrandt1, Ralf Birkenhäger2
1Neurobiological Research Laboratory, Section for Clinical and Experimental Otology, University Medical Center Freiburg, Freiburg, Germany.
Frontiers in Cellular Neuroscience
|March 10, 2018
Summary
Glial cells, including astrocytes and microglia, are crucial for adjusting neuronal inhibition to excitation in the auditory cortex following cochlear stimulation, especially in deafened rats. This study reveals significant glial activation and tissue remodeling in response to electrical stimulation.
Area of Science:
- Neuroscience
- Auditory system research
- Glial cell biology
Background:
- Neuron-glia interactions are vital for brain homeostasis and plasticity.
- The mechanisms underlying these interactions in the auditory system remain largely unknown.
Purpose of the Study:
- To investigate stimulation-dependent cellular remodeling in the central auditory brain.
- To compare responses in hearing-experienced versus neonatally deafened rats.
Main Methods:
- Intracochlear electrical stimulation in adult rats (hearing and deafened).
- Auditory brainstem responses (ABRs) for hearing assessment.
- Immunocytochemistry and in situ hybridization for Fos, GFAP, IBA1, GAD65/67.
Main Results:
- Deaf rats showed widespread Fos expression in the inferior colliculus (IC) compared to restricted expression in hearing rats.
- Deaf rats exhibited significant astrocytic hypertrophy (GFAP increase) and microglial activation (IBA1 increase).
- Increased GABAergic markers (GAD65/67) and neuron-glia proximity were observed in deaf rats' IC, without cell death.
Conclusions:
- Glial cell growth and activity are essential for adapting neuronal inhibition to excitation in the auditory cortex.
- The auditory system demonstrates significant plasticity in response to electrical stimulation, modulated by glial cells.
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