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.

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 （AP 1）. 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 i00 dB 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 AP 1 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 AP 1 expression following noise exposure.