Drug to reduce brain inflammation CURED tinnitus in mice
Drug to reduce brain inflammation CURED tinnitus in mice – paving the way towards a pill for humans
- The condition was stopped in mice by blocking a protein that fuels brain inflammation
- The Arizona team are hopeful it will lead to a gene therapy to combat tinnitus and other hearing loss disorders
A pill to cure the misery of tinnitus could be on the horizon following a breakthrough by scientists.
The debilitating condition was stopped in mice by blocking a protein that fuels brain inflammation.
The US team are hopeful it will lead to a gene therapy to combat ringing in the ears and other hearing loss disorders.
Recent research suggests hearing loss causes inflammation – the immune system’s response to injury and infection – in the auditory pathway
About one in 10 people suffers from tinnitus which can cause stress, sleep difficulties, anxiety and hearing loss.
The condition is often linked with Meniere’s disease, diabetes, multiple sclerosis and depression. But it is not known how it develops, and there is no cure.
The study, published in the journal PLOS Biology, suggests it is caused by a molecule called TNF-A (tumor necrosis factor alpha) that disrupts communication between neurons.
Blocking it pharmacologically also prevented tinnitus in lab rodents that developed the condition after being exposed to loud noise for two hours.
The findings suggest neuro-inflammation may be a therapeutic target for treating tinnitus and other hearing problems, said the researchers.
Study co-author Dr Shaowen Bao said: ‘Genetic knock out of TNF-A or pharmacologically blocking its expression prevented neuro-inflammation and ameliorated the behavior associated with tinnitus in mice with noise induced hearing loss.’
Analysis showed inflammation in a sound-processing region of the brain controls ringing in the ears in the affected mice that have noise-induced hearing loss.
Dr Bao, a neuroscientist at the University of Arizona, said: ‘Hearing loss is a widespread condition that affects approximately 500 million individuals, and is a major risk factor for tinnitus – the perception of noise or ringing in the ears.’
Recent research suggests 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.
Dr Bao and colleagues examined neuro-inflammation – inflammation that affects the nervous system – in the auditory cortex of the brain following noise-induced hearing loss, and its role in tinnitus, in the rodent models.
He said: ‘The results indicate 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.’
Dr Bao added: ‘These results implicate neuro-inflammation as a therapeutic target for treating tinnitus and other hearing loss related disorders.’
But he pointed out that although the therapy was successful in the animals, its potential adverse affects need to be thoroughly investigated before any human trials.
The most common cause of tinnitus is damage and loss of the tiny sensory hair cells in the cochlea of the inner ear. This tends to happen as people age, and it can also result from prolonged exposure to excessively loud noise. Hearing loss may coincide with tinnitus.
There is no cure, but there are ways of managing it. Most people with chronic tinnitus adjust to the ringing over time, but one in five will find it disturbing or debilitating.
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