Sound exposure dynamically induces dopamine synthesis in cholinergic LOC efferents for feedback to auditory nerve fibers

Lateral olivocochlear (LOC) efferent neurons modulate auditory nerve fiber (ANF) activity using a large repertoire of neurotransmitters, including dopamine (DA) and acetylcholine (ACh). Little is known about how individual neurotransmitter systems are differentially utilized in response to the ever-...

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Bibliographic Details
Published in:eLife 2020-01, Vol.9
Main Authors: Wu, Jingjing Sherry, Yi, Eunyoung, Manca, Marco, Javaid, Hamad, Lauer, Amanda M, Glowatzki, Elisabeth
Format: Article
Language:English
Subjects:
Acetylcholine
Acoustics
Animal experimentation
Animals
Auditory nerve
auditory nerve fiber
Cholinergic Neurons - metabolism
Cochlear Nerve - metabolism
Dopamine
Dopamine - biosynthesis
Dopamine receptors
Enzymes
Hair
Hair Cells, Auditory, Inner - metabolism
Hearing protection
Hydroxylase
Hydroxylases
Mice
Neurons
Neurons, Efferent - metabolism
Neuroscience
Neurotransmitters
Noise
noise damage
olivocochlear efferents
Phenols (Class of compounds)
Rats
Rodents
Sound
spiral ganglion neuron
Synapses
Tyrosine
Tyrosine 3-monooxygenase
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Summary:Lateral olivocochlear (LOC) efferent neurons modulate auditory nerve fiber (ANF) activity using a large repertoire of neurotransmitters, including dopamine (DA) and acetylcholine (ACh). Little is known about how individual neurotransmitter systems are differentially utilized in response to the ever-changing acoustic environment. Here we present quantitative evidence in rodents that the dopaminergic LOC input to ANFs is dynamically regulated according to the animal's recent acoustic experience. Sound exposure upregulates tyrosine hydroxylase, an enzyme responsible for dopamine synthesis, in cholinergic LOC intrinsic neurons, suggesting that individual LOC neurons might at times co-release ACh and DA. We further demonstrate that dopamine down-regulates ANF firing rates by reducing both the hair cell release rate and the size of synaptic events. Collectively, our results suggest that LOC intrinsic neurons can undergo on-demand neurotransmitter re-specification to re-calibrate ANF activity, adjust the gain at hair cell/ANF synapses, and possibly to protect these synapses from noise damage.
ISSN:2050-084X
2050-084X
DOI:10.7554/elife.52419