[Effects of noise on antioxidant enzymes of cochlea in guinea pigs].

OBJECTIVE

To investigate the effect of noise on the antioxidant enzymes of cochleae.

METHODS

16 male pigmented guinea pigs (250 - 300 g) were randomly divided into 2 groups, control group and noise group. Each group had 8 animals. The animals in noise group were performed auditory evoked brainstem responses (ABR) recording before and after exposure to a continuous noise (4 kHz, octave band, 100 dB, SPL) 8 h/d for 3 consecutive days. Immediately at the end of the third day's noise exposure after ABR recording, guinea pigs were decapitated. Both the right and the left cochlea with the bony capsule removed were homogenized, and the supernatants were prepared for assays. Reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GSH-Px) were measured.

RESULTS

ROS level of the noise group [(281.2 +/- 3.5) U/mg pro] was significantly higher than that of the control group [(273.0 +/- 3.2) U/mg pro, P < 0.05] and SOD, CAT and GSH-Px activities of the noise group [(206.5 +/- 5.1) NU/mg pro, (47.0 +/- 9.0) U/g pro, (14.1 +/- 2.5) U/mg pro respectively] were significantly lower than that of the control group [(221.8 +/- 4.8) NU/mg pro, (60.8 +/- 9.9) U/g pro, (21.1 +/- 3.1) U/mg pro respectively, P < 0.05].

CONCLUSION

Noise may damage the defensive system of antioxidant enzymes in cochlea.