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.