Ginkgo Biloba Alleviates Noise-Induced Hearing Loss through Inflammatory Pathways

by | Sep 29, 2020 | 2018, Ear, Nose and Throat, Ginkgo Biloba

Written by Angeline A. De Leon, Staff Writer. Ginkgo Biloba with its anti-inflammatory and antioxidative properties may be an effective treatment for noise-induced hearing loss (NIHL).

gingko biloba - botanicalsNoise-induced hearing loss (NIHL) is permanent hearing loss caused by chronic exposure to loud sound and involves a mixture of environmental and genetic influences 1. While studies are still underway to determine the exact pathophysiology of NIHL, it is suggested that an inflammatory process may be involved wherein high noise levels trigger an increase in oxidative stress which leads to deterioration of the cochlea’s outer hair cells 2. In line with this view, research suggests that circulating levels of pro-inflammatory cytokines (interleukin-1 beta, IL-1 beta; interleukin-6, IL-6; tumor necrosis factor-alpha, TNF-alpha) are elevated following noise exposure 3. Other studies show that NIHL is also associated with changes in the expression of heat shock factor-1 (HSF-1, involved in regulation of pro-inflammatory cytokines), heat shock protein-70 (HSP-70, exerts protective anti-inflammatory effect), and cyclooxygenase-2 (COX-2, involved in promotion of inflammation) 4,5. Gingko biloba is a known anti-inflammatory and antioxidant associated with various health benefits such as anti-tumor effects 6. Gingko biloba extract also demonstrates the ability to facilitate recovery from sudden hearing loss and protect cochlear hair cells from ear poisoning by reducing reactive oxygen species 7,8. To evaluate the protective anti-inflammatory benefits of gingko biloba on NIHL, a 2018 study 9 in Auris Nasus Larynx examined the impact of gingko biloba extract on IL-6, IL-1 beta, TNF-alpha, HSP-70, HSF-1, and COX-2 in a rat model of NIHL.

A litter of 32 healthy female Sprague Dawley rats were randomized into 4 groups: an acoustic trauma group (AT) that was exposed to white noise (100 dB SPL) for 8 hours; a gingko biloba group (GB) that was administered gingko biloba extract (100 mg/kg/day) for 21 days; a group that was exposed to white noise for 8 hours and then administered gingko biloba extract (100 mg/kg/day) for 21 days (AT +GB); and a non-treatment group (control). Over the course of the study, audiological evaluations were carried out in rats using auditory brainstem response (ABR) to determine hearing level. On Day 21, intercardiac blood samples were collected and analyzed to determine levels of IL-6, IL-1 beta, TNF-alpha, HSP-70, HSF-1, and COX-2 using enzyme linked immunosorbent assays (ELISA) and Western blot analysis.

At the end of the study, researchers observed a significant increase in ABR threshold from baseline to post-traumatic Day 7 for the AT + GB group (p < 0.005). As predicted, levels of IL-1 beta, IL-6, and TNF-alpha were significantly increased for the AT group compared to all other groups (p < 0.005). The GB and AT + GB groups showed no such significant elevations in pro-inflammatory cytokine levels. Western blot analysis also showed that HSP-70 and HSF-1 levels were significantly decreased in the AT group, compared to the GB group and AT + GB group (p < 0.005). COX-2 levels, however, were found to be significantly higher in the AT group vs. all other groups (p < 0.005).

Overall, evidence from the current study provides novel insight into the effects of gingko biloba intake on biochemical pathways associated with NIHL. In general, gingko biloba was seen to protect against the increase in pro-inflammatory cytokines caused by acoustic trauma, inhibiting the expression of IL-1 beta, IL-6, TNF-alpha, and COX-2, relative to the AT group. Compared to the AT group, treatment with the herbal remedy was also associated with elevations in HSP-70 and HSF-1, enzymes associated with protective effects against oxidative stress. In line with previous research (7, 8), the current trial suggests that supplementation with gingko biloba may be an effective treatment for otologic diseases. Replication of findings in a human model of NIHL would be an important next step.

Source: Dogan R, Sjostrand AP, Yenigun A, et al. Influence of gingko biloba extract (EGb 761) on expression of IL-1 beta, IL-6, TNF-alfa, HSP-70, HSF-1, and COX-2 after noise exposure in the rat cochlea. Auris Nasus Larynx. 2018; 45: 680-685. DOI: 10.1016/j.anl.2017.09.015.

© 2017 Elsevier B.V. All rights reserved.

Posted September 29, 2020.

Angeline A. De Leon, MA, graduated from the University of Illinois at Urbana-Champaign in 2010, completing a bachelor’s degree in psychology, with a concentration in neuroscience. She received her master’s degree from The Ohio State University in 2013, where she studied clinical neuroscience within an integrative health program. Her specialized area of research involves the complementary use of neuroimaging and neuropsychology-based methodologies to examine how lifestyle factors, such as physical activity and meditation, can influence brain plasticity and enhance overall connectivity.

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