Correlation between plasma levels of radical scavengers and hearing threshold among elderly subjects with age-related hearing loss

Abstract

The mean ± SD of plasma melatonin among the subjects with normal hearing (NH) (0-30 dB) and those with HL in the speech frequencies was 18.3 ± 3.6 μg/L and 16.4 ± 4.7 μg/L, respectively. In the high frequencies the values were 17.7 ± 6.2 μg/L and 13.1 ± 6.4 μg/L for NH and HL, respectively. For vitamin C, the mean ± SD among subjects with NH and those with HL in the speech frequencies were 1.2 ± 0.2 μg/L and 1.0 ± 0.1 μg/L, respectively. In the high frequencies, the values were 1.0 ± 0.2 μg/L and 0.9 ± 0.3 μg/L for NH and HL, respectively. Among subjects with high frequency HL, Spearman's correlation revealed significant correlation between increasing hearing threshold and melatonin (correlation coefficient = -0.30, p = 0.01), but not for vitamin C (correlation coefficient = -0.12, p = 0.22). Linear regression, adjusting for age, still revealed significant correlation between the melatonin (correlation coefficient = -0.03, p = 0.00) and hearing threshold in the high frequencies.

Presbycusis: An Update on Cochlear Mechanisms and Therapies

“…Increasing evidence links oxidative stress to ARHL [58,59]. Low serum levels of the ROS scavenger melatonin are significantly associated with the occurrence of high-frequency hearing loss in the elderly [60]. Experimental evidence also indicates that lipid peroxidation, oxidative DNA damage and glutathione-conjugated proteins, reduced expression of antioxidant enzymes such as catalase, and MnSOD and cytosolic SOD were associated with cochlear aging in mice [59,61,62].…”

“…In the cochlea, high levels of Interleukin-1 Beta (IL-1β) and tumor necrosis factor (TNF) have been observed in aging cochleae [59]. Furthermore, an association between systemic inflammation and ARHL has recently been noted in human studies [60,88,89]. The polymorphisms of genes encoding inflammatory mediators (TNF-α rs1800630 and TNFRSF1B rs1061624) have also been reported to contribute to the incremental risk of hearing impairment in elderly Japanese [35].…”

Hormone Therapy: Challenges for Treating Hearing Impairments

“…In addition, there is a relationship between the hearing threshold and serum MT, being low plasma levels of this hormone a significant factor in the development of high frequency (HL) hearing loss among the elderly. However, this relationship is not linear [47].…”

Recognition and Control of the Progression of Age-Related Hearing Loss

“…135 Melatonin, an indole hormone secreted primarily by the pineal gland, functions as a regulator of circadian rhythms and has been postulated to enhance the defense capacity of many anti-oxidative enzymes and thus to protect DNA, membrane lipids, and possibly cytosolic proteins against oxidative damage, thus functioning as an important neural anti-oxidant and free radical scavenger. 134,136,137 A cross-sectional study was carried out to determine the correlation between the hearing threshold and the plasma melatonin and ascorbic acid (vitamin C) levels. Low plasma levels of melatonin are significantly associated with high-frequency hearing loss (HL) among the elderly with ARHL.…”

“…Low plasma levels of melatonin are significantly associated with high-frequency hearing loss (HL) among the elderly with ARHL. 137 Melatonin also plays a role in the appearance of autoimmune deafness by acting upon lymphocytes. 138 Lecithin, as a polyunsaturated phosphatidylcholine (PPC), is an important component of biological membranes.…”