Effects of aging on cochlear monoamine turnover.

The aging of the cochlear dopaminergic system has been analyzed by quantifying the levels of dopamine (DA) and its metabolites (3,4-dihydroxyphenylacetic acid, DOPAC, and homovanillic acid, HVA) in adult rats aged 3, 12 or 24 months. The main results were an increase in DA, DOPAC and HVA basal concentrations in aged females with respect to the adults (3 or 12 months old), while just DA and DOPAC increased in aged males. A higher synthesis of DA in aged animals could support these findings, which could indicate some kind of compensatory mechanism related to presbycusis.