OBJECTIVE

To study the preventive effects of vitamin E on short-term noise-induced hearing loss (NIHL).

METHODS

Forty-eight male pigmented guinea pigs were randomly divided into 6 groups, 8 animals in each group. The animals of group 1, 2, 3, 4 were exposed to the noise (4 kHz octave band noise, 100 dB SPL), 8 hours per day for 3 days consecutively and received normal saline, corn oil, 10 mg/kg vitamin E, 50 mg/kg vitamin E respectively daily by intraperitoneal injection from 3 days before the noise exposure, through the 3 noise exposure days to 3 days after the noise exposure. The animals of group 5 and group 6 days were not exposed to the noise but received normal saline and 50 mg/kg vitamin E injection respectively at the same time as that of group 1, 2, 3, 4. The preventive effects of vitamin E on NIHL were determined by comparing the threshold shifts of auditory brainstem responses (ABR) immediately, on the second day and on the 8th day after the exposure.

RESULTS

The ABR threshold shifts immediately, on the second day and on the 8th day after the exposure for group 3 at 2, 4 and 8 kHz were (15.9 +/- 6.8), (39.4 +/- 4.8), (42.5 +/- 6.3), (0.3 +/- 2.5), (19.1 +/- 7.9), (21.9 +/- 6.4), (0.3 +/- 1.6), (10.9 +/- 8.6), (12.2 +/- 8.1) dB, respectively, which were significantly lower than those for group 1 [(30.9 +/- 11.3), (47.8 +/- 8.8), (49.7 +/- 6.9), (10.0 +/- 3.5), (29.1 +/- 6.5), (29.1 +/- 7.6), (4.7 +/- 3.6), (20.3 +/- 6.5), (17.5 +/- 9.0) dB, respectively] (P < 0.05). The ABR threshold shifts immediately, on the second day and on the 8th day after the exposure for group 4 at 2, 4 and 8 kHz were respectively (14.4 +/- 5.3), (36.6 +/- 4.4), (43.1 +/- 2.9), (0.3 +/- 2.5), (16.9 +/- 4.6), (19.4 +/- 3.2), (0.0 +/- 3.7), (7.5 +/- 4.2), (9.1 +/- 4.2) dB, which were significantly lower than those for group 1 (P < 0.05).

CONCLUSION

Vitamin E has some preventive effects on the NIHL.