Ototoxic effects of styrene exposure during gestation and lactation in rats.
Li-M; Chen-G-D; Tanaka-C; Bielefeld-E; Henderson-D
Abstr 31st Midwinter Res Meet 2008 Feb; 31:53
Styrene is extensively used in industries and many workers, including women, are exposed to styrene. Styrene ototoxicity has been well documented. However, the impact of styrene ototoxicity during gestation and lactation is still unclear. We hypothesize that styrene may induce less ototoxic effect on pregnant rats because of high estrogen levels, but may induce significant ototoxic effects on the development of the babies' auditory system. Five pregnant rats were exposed to styrene by gavage at a dose of 400 mg/kg/day starting from the fourth day of gestation for 5 days per week for 6 weeks. Six male rats were exposed at the same dosage for the same period for comparison. Two pregnant rats were unexposed and their offspring were used as controls. Three days after the last gavage of the 6-week styrene exposure, threshold shift in the mother rats and the male rats was assessed using compound action potential (CAP) recording, and their auditory hair cells were counted. the styrene exposure caused an about 15-20-dB threshold shift and 30-40% outer hair cell (OHC) loss in the mid-frequency region in both groups of the pregnant rats and the males rats. Threshold shifts of the baby rats were measured 2 months after birth by recording of both auditory brainstem response (ABR) and CAP. Significant CAP threshold shift was only observed in those rats from one mother but not the other four mothers. Interestingly, ABR threshold shift was observed in all of the 5 families. Almost all of the baby rats have normal cochlear anatomy, i.e.: no hair cells loss. The mechanism for the hearing loss in the mother rats and the pups is discussed. This study was supported by NIOSH grant 1R01OH008113-01A1.
Noise-exposure; Exposure-levels; Noise-induced-hearing-loss; Noise-exposure; Noise; Hearing; Hearing-disorders; Hearing-loss; Laboratory-animals; Animals; Styrenes; Exposure-levels
Abstracts of the 31st Midwinter Research Meeting
Washington University, St. Louis