Hearing loss resulting from exposure to loud sounds is very common. Now, using a supplement that is a source of Vitamin B3 called nicotinamide riboside or NR, scientists have successfully prevented noise-induced hearing loss in mice.
Our ears are very sensitive and can be damaged by a variety of things from disease to noise or trauma. Intense noises, for example, can induce hearing loss by triggering the degeneration of the nerve cells, or neurons, that are connected to the tiny hair cells of the cochlea – a tiny snail-shaped structure inside the ear that transmits audio signals to the brain.
Scientists from Weill Cornell Medical College and the Gladstone Institutes wondered whether it might be possible to somehow protect these nerve cells from harm.
They began by contemplating using a molecule called NAD+ which has been shown to exert protective effects to neurons in cell culture. As this molecule is unstable and difficult to get inside cells, the researchers turned to a molecule called nicotinamide riboside (NR).
NR, which is found in trace amounts in certain foods, is a precursor of NAD and also a source of Vitamin B3. Furthermore, NR enters cells easily and is quickly absorbed when administered orally, meaning it is an ideal drug candidate.
To investigate whether NR could prevent nerve damage in the cochlea, the team administered the compound to mice both before and after exposing them to loud noises. They found that NR successfully protected the nerve endings, avoiding both short-term and long-term hearing loss. Furthermore, they found it to be equally effective whether it was administered before or after noise exposure.