Oral supplementation of the natural radical scavenger ascorbic acid reduces the NO-production rate in the inner ear in noisy conditions. This finding supports the concept of inner ear protection by ascorbic acid supplementation.

No abstract

A high dose of ascorbic acid lowers NO production in the inner ear, reduces hearing loss, and protects the cochlea from nitroactive stress.

In diff erent approaches, it was shown that 17β-estradiol can infl uence NO production differently depending on the tissue. In the endothelium of blood vessels, a 17β-estradiol-dependent increase in the endothelial nitric oxide synthase (eNOS) expression or an upregulation of its activity was detected, both resulting in an increased NO concentration [ 12 ]. On the other hand, a 17β-estradiol-dependent downregulation of nitric oxide synthase activity was identifi ed in the uterus and vagina of rabbits [ 13 ]. At the cellular level, an estrogen-mediated inhibition of Ca 2 + infl ux via L-type Ca 2 + channels was described for murine cardiomyoctes [ 14 ] and this attenuated glutamate-induced cell death in a ventral spinal motoneuron and neuroblastoma hybrid cell line (VSC 4.1) [ 15 ]. Thus, 17β-estradiol was found to fulfi ll multiple tasks in NO-regulated vertebrate physiology including neuroprotection [ 16-19 ]. In addition, clinical and experimental studies have shown that estradiol