Reducing Brain Inflammation Treats Tinnitus

In mice with noise-induced hearing loss, inflammation in a sound-processing region of the brain mediates ringing in the ears, revealed study in the open-access journal PLOS Biology by Shaowen Bao of the University of Arizona, and colleagues. // Recent studies indicate that hearing loss causes inflammation -- the immune system's response to injury and infection -- in the auditory pathway. But its contribution to hearing loss-related conditions such as tinnitus is still poorly understood. To address this gap in knowledge, Bao and his colleagues examined neuroinflammation -- inflammation that affects the nervous system -- in the auditory cortex of the brain following noise-induced hearing loss, and its role in tinnitus, in rodent models.

The results indicate that noise-induced hearing loss is associated with elevated levels of molecules called proinflammatory cytokines and the activation of non-neuronal cells called microglia -- two defining features of neuroinflammatory responses--in the primary auditory cortex.

Experiments in mice that incur noise-induced hearing loss showed that a cell-signaling molecule called tumor necrosis factor alpha (TNF-α) mediates neuroinflammation, tinnitus, and synaptic imbalance -- an altered pattern of signaling between neurons. Moreover, the researchers found that pharmacological blockade of TNF-α or depletion of microglia prevented tinnitus in mice with noise-induced hearing loss. According to the authors, the findings suggest that neuroinflammation may be a therapeutic target for treating tinnitus and other hearing loss-related disorders.

Source-Eurekalert