Scientists have restored hearing in mice partly deafened by noise, using advanced tools to boost the production of a key protein in their ears.
By demonstrating the importance of the protein, called NT3, in maintaining communication between the ears and brain, these new findings pave the way for research in humans that could improve treatment of hearing loss caused by noise exposure and normal ageing.
Researchers at the University of Michigan Medical School's Kresge Hearing Research Institute and Harvard University report understanding NT3's role in the inner ear, and the impact of increased NT3 production on hearing after a noise exposure.
Their work also illustrates the key role of cells that have traditionally been seen as the "supporting actors" of the ear-brain connection.
Called supporting cells, they form a physical base for the hearing system's "stars": the hair cells in the ear that interact directly with the nerves that carry sound signals to the brain.
This new research identifies the critical role of these supporting cells along with the NT3 molecules that they produce.
NT3 is crucial to the body's ability to form and maintain connections between hair cells and nerve cells, the researchers said.
This special type of connection, called a ribbon synapse, allows extra-rapid communication of signals that travel back and forth across tiny gaps between the two types of cells.
"It has become apparent that hearing loss due to damaged ribbon synapses is a very common and challenging problem, whether it's due to noise or normal ageing," said Gabriel Corfas, who led the team and directs the U-M institute.
"We began this work 15 years ago to answer very basic questions about the inner ear, and now we have been able to restore hearing after partial deafening with noise, a common problem for people. It's very exciting," said Corfas.
The research was published in the journal eLife.
