Molecular mechanisms underlying the protective effects of hydrogen-saturated saline on noise-induced hearing loss

Authors
Journal
Acta Oto-Laryngologica
Year
DOI
10.1080/00016489.2017.1328743
Study Type
Guinea Pig
Outcome
Positive
Peer Reviewed
Yes
Country
China
Health Condition
Noise-induced hearing loss (NIHL)
Body System
Auditory system

TL;DR

Hydrogen-saturated saline injections can significantly reduce hearing damage caused by loud noise in guinea pigs by decreasing inflammation and oxidative stress in the ear.

Key Finding

Pre-treatment with hydrogen-saturated saline significantly reduced noise-induced hearing loss in guinea pigs and lowered markers of oxidative damage and inflammatory chemicals in the cochlea (inner ear).

Summary

Researchers tested whether hydrogen-saturated saline (a salt solution containing dissolved hydrogen gas) could protect guinea pigs' hearing from loud noise damage. Guinea pigs given hydrogen-saturated saline before noise exposure had less hearing loss than those given regular saline. The protective effect appeared to work through two mechanisms: reducing harmful molecules called free radicals (measured by 8-HOdG levels) and reducing inflammatory chemicals in the inner ear.

Practical Takeaway

This is early animal research showing hydrogen-saturated saline may protect hearing from noise damage through antioxidant and anti-inflammatory pathways. However, this was only tested in guinea pigs, not humans, so it's unclear whether similar effects would occur in people or what dose and timing would be needed. Much more research is required before any conclusions about human hearing protection can be drawn.

Abstract

Objectives: This study aimed to explore the molecular mechanism of the protective effects of hydrogen-saturated saline on NIHL. Methods: Guinea pigs were divided into three groups: hydrogen-saturated saline; normal saline; and control. For saline administration, the guinea pigs were given daily abdominal injections 3 d before and 1 h before noise exposure. ABR were tested to examine cochlear physiology changes. The changes of 8-hydroxy-desoxyguanosine (8-HOdG), interleukin-1 (IL-1), interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor-α (TNF-α), intercellular cell adhesion molecule-1 (ICAM-1) and high mobility group box-1 protein (HMGB1) in the cochlea were also examined. Results: The results showed that pre-treatment with hydrogen-saturated saline could significantly attenuate noise-induced hearing loss. The concentration of 8-HOdG was also significantly decreased in the hydrogen-saturated saline group compared with the normal saline group. After noise exposure, the concentrations of IL-1, IL-6, TNF-α, and ICAM-1 in the cochlea of guinea pigs in the hydrogen-saturated saline group were dramatically reduced compared to those in the normal saline group. The concentrations of HMGB-1 and IL-10 in the hydrogen-saturated saline group were significantly higher than in those in the normal saline group immediately and at 7 d after noise exposure. Conclusions: This study revealed for the first time the protective effects of hydrogen-saturated saline on noise-induced hearing loss (NIHL) are related to both the anti-oxidative activity and anti-inflammatory activity.