The effect of curcumin as an antioxidant on cochlea fibroblasts in ototoxic rat models

Aminoglycosides(e.g. Gentamicin) are ototoxic drugs and widely prescribed due to their effective antimicrobial actions and affordable prices. This study focused on determining protective effect of curcumin against the damage caused by aminoglycosides. We aimed to demonstrate the potential of curcumin as an antioxidant to increase the expressions of superoxide dismutase(SOD) in fibroblasts of cochlea lateral wall in ototoxic rat models. The experiment was conducted with randomized post test-only control group design by using 32 male Rattusnorvegicus adults which received a combination of gentamicin and curcumin with different durations and doses. Then, the rats underwent terminations and immunohistochemical assay to determine the expression of SOD. The rats receiving gentamicin injection showed significantly decreased expression of SOD(P<0.05), and the administration of curcumin before and after the gentamicin injection showed significantly increased expression of SOD(P<0.05). Collectively, we showed that curcumin was an antioxidant against oxidative stress due to ototoxicity evidenced by the expression of SOD.

Effect of Curcuma longa L.extract on the AP1 expression in rat cochlear fibroblasts under noise conditions

Noise-induced cellular stress can cause damage to fibroblasts within the cochlear supporting tissues and lateral wall. In the present study, we aimed to evaluate the role of curcumin as the safe and effective therapeutic agent in the prevention and treatment of this condition according to the expression of activator protein-1(AP1). A total of 24 Rattus norvegicus were randomly divided into four groups(n = 6). Group 1: control; group 2: noise(+); group 3: noise(+), 50 mg/day curcumin(+); group 4: noise(+), 100 mg/day curcumin(+). All groups(except for group 1) were subjected to a sound pressure level(SPL) of 100 d B for 2 h/day during 2 weeks. Curcumin used in this study was derived from Curcuma longa L.(Turmeric), and it was orally administered for 2 weeks. All samples were immunohistochemistrically examined for the expression of AP1 in cochlear fibroblasts. The results showed that there were significant differences for the AP1 expression(P<0.05) among all groups, except for between groups 1 and 3, or between groups 1 and 4. Our data proved that curcumin was potentially effective in the prevention and treatment of damage of fibroblasts within the cochlear supporting tissues and lateral wall due to the decreased AP1 expression following noise exposure.