Phytosterols, possible therapeutic strategy to prevent hearing loss in mice

2023-08-25 13:06:45

Argentine researchers have announced this week in the journal PLoS Biology their findings of laboratory regarding the effectiveness that the phytosterol supplements in the Hearing loss age related.

hearing deficit linked to aging is associated with a cholesterol lowering in the inner ear. The experiments of this team led by María Eugenia Gomez-Casati show that phytosterol supplements can make the lost cholesterol function and prevent sensory dysfunction in mice.

Sensory cells in the inner ear, called outer hair cells, amplify sounds by changing their length

Scientists from CONICET, the Institute of Pharmacology of the Faculty of Medicine (University of Buenos Aires), the Mercedes Medical Research Institute and the National University of Córdoba, in Argentina, hypothesized that hearing loss could be related to cholesterol loss in outer hair cells.

Las sensory cells of the inner ear, called outer hair cells, amplify sounds by changing their length. With age, these cells lose their ability to stretch in response to stress. sound vibrations they enter the inner ear, preventing their amplification and causing hearing loss.

Given that cholesterol is a key factor in the stretch response and that brain cholesterol has recently been shown to decline with age, the researchers hypothesized that hearing loss might be related to a lack of cholesterol in hair cells. external. so this hypothesis was tested on mice.

Prestin expression in the outer hair cells of mice treated with efavirenz and efavirenz plus phytosterols.

First, the researchers measured the amount of CYP46A1 in these inner ear cells, since this difficult help to degrade and recycle cholesterol.

As expected, they found more CYP46A1 in the ears of the older mice than in the younger ones, and consequently a reduction in cholesterol.

They then demonstrated the cause-effect relationship. inducing hearing loss in young miceas indicated by abnormal production of inner ear cells, by overactivation of CYP46A1 with a drug.

Finally, they analyzed whether the increased cholesterol in the brain could counteract the effect of the drug.

Phytosterols can be found in many over-the-counter supplements and may be a practical way to combat age-related hearing loss.

Since cholesterol itself cannot enter the brain from the blood, the researchers used plant compounds similar to cholesterol, called phytosterols, which can. Young mice that received both the CYP46A1-activating drug and three weeks of dietary phytosterols showed improved outer hair cell function.

Since phytosterols can be found in many over the counter supplementscould be a practical way to combat age-related hearing loss.

However, as the authors caution, its effects on hearing loss will need to be tested directly in models of elderly miceas well as in humans, before more definitive conclusions can be drawn

Likewise, the researchers add that, thanks to this work, they were able to show that aging triggers the loss of cholesterol from the sensory cells of the inner ear and that “a retroviral treatment widely used for patients with HIV/AIDS reproduces the cholesterol loss observed in elderly individuals and leads to impaired outer hair cell function”.

In addition, they describe their findings as “promising”, insofar as “these deficits can be reversed, in part, by supplementing with phytosterols.”

Reference:

Gómez-Casati, ME et al. “Phytosterols reverse antiretroviral-induced hearing loss, with potential implications for cochlear aging”. PLoS Biology (2023)

Fuente: CONICET

Rights: Creative Commons.