Resumen:
Dietary antioxidants, polyphenols, have
been found to be beneficial in protecting against the
generation of oxidative stress in various diseases
associated with aging. Age-related hearing loss (AHL)
is the number one neurodegenerative disorder on our
aged population. Sprague–Dawley rats divided into
five groups according to their age (3, 6, 12, 18 and
24 months old) and treated with 100 mg/day/kg body
weight of polyphenols were used. Then, cochleae were
harvested to measure caspase activities (- 3, - 8 and
- 9), caspase-3 gene expression, ATP levels, Bax,
BcL-2 and p53 levels. 8-OHdG levels (marker of DNA
oxidative damage) and annexin-V were also measured
in cochleae. Increased levels of caspase-3 and 9 in
cochlea were observed with age and this effect was
attenuated by polyphenol treatment. In addition, ATP
and Bcl-2 levels in older rats were recovered after
administration of polyphenols, while Bax and p53
levels protein decreased. Oral supplementation with
polyphenols also reduces DNA oxidative damage of
cochlear cell. Treatment with polyphenols inhibits the
activation of age-related apoptotic signaling by
decreasing oxidative stress inside the rat cochlea.