Combined effects of exposure to styrene and ethanol on the auditory function in the rat

Loquet, Gérard Sylvian Jean Marie; Campo, Pierre; Lataye, R; Cossec, Benoît; Bonnet, Pierre

doi:10.1016/s0378-5955(00)00151-9

Cited by 28 publications

(16 citation statements)

References 31 publications

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“…Several studies [20,28,29] have demonstrated that long-term exposure to ethanol alone had no effect on auditory sensitivity and did not cause any toxicity to the outer hair cells in rats. However, Morizono and Sikora [19] found a reduction in cochlear microphonics after topical application of alcohol to the inner ear of guinea pigs.…”

Section: Discussionmentioning

confidence: 99%

“…In 1981, Morizono and Sikora [19] reported that topical application of ethanol causes a reduction of all bioelectric functions of the inner ear in guinea pigs. However, in another experiment, exposure to ethanol alone was found to have no effects on auditory sensitivity and did not cause any toxicity to outer hair cells [20]. These conflicting results may be due to differences in dosages, ways or durations of alcohol exposure.…”

Section: Introductionmentioning

confidence: 93%

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Effects of Alcohol and Noise on Temporary Threshold Shift in Guinea Pigs

Liu

Hsu

Hwang

et al. 2004

ORL

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The purpose of this study was to investigate the effects of concomitant exposure to noise and alcohol on the auditory thresholds. Twenty-four guinea pigs were equally divided into three groups: the acute intoxication group, the chronic intoxication group and the control group. Animals in the acute group received single intraperitoneal injections of ethanol (2 g/kg). In the chronic group, alcohol was administered via drinking water (10%, v/v) over a 60-day period. All animals were exposed to a white noise at the intensity of 105 dB A for 30 min. Auditory brainstem response (ABR) thresholds and distortion product otoacoustic emission (DPOAE) levels were measured before, immediately after noise exposure and also 1, 2, and 7 days following exposure. The results showed: first, acute alcohol injection caused a significant, temporary elevation of ABR threshold (4.8 dB in average), while chronic alcohol treatment did not change auditory threshold significantly. Second, noise exposure induced a mean threshold shift of 15.4– 19.7 dB. ABR threshold returned to normal 2 days after exposure. Both acute and chronic alcohol treatment did not alter the magnitude and time course of recovery of the temporary threshold shift (TTS). Third, the mean DPOAE amplitudes decreased at most frequencies following acute injection of alcohol. However, the differences did not reach statistical significance. Fourth, the mean DPOAE levels dropped 3.4–9.6 dB in all groups after noise exposure and returned to normal 1 day to 2 days after noise. There were no significant differences in the amount of DPOAE suppression after noise between the three groups. In summary, we have found that acute and chronic treatment of alcohol in combination with noise did not significantly exacerbate TTS or decrease DPOAE amplitudes relative to noise exposure alone.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 93%

Effects of Alcohol and Noise on Temporary Threshold Shift in Guinea Pigs

Liu

Hsu

Hwang

et al. 2004

ORL

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“…It targets OHCs as well as Deiters cells (DCs) starting from the third row Gagnaire and Langlais, 2005;Lataye et al, 2000Lataye et al, , 2001Lataye et al, , 2003Loquet et al, 1999Loquet et al, , 2000Makitie et al, 2003 Abbreviations: CAP, compound action potential; DC, Deiters cell; FITC, fluorescein isothiocyanate; NIHL, noise-induced hearing loss; I/O, input/output; IHC, inner hair cell; IP, inner pillar cell; OHC, outer hair cell; OP, outer pillar cell; PBS, phosphate buffer saline; PTS, permanent threshold shift; SDH, succinate dehydrogenase; TNBTZ, tetranitro blue tetrazolium relatively insensitive to styrene exposure. Previously, we have observed that, even in cochleae in which all OHCs were missing, the maximal CAP amplitude was still at the normal level, indicating that the remaining IHCs were still functioning after the loss of all OHCs.…”

Section: Introductionmentioning

confidence: 99%

Relation between outer hair cell loss and hearing loss in rats exposed to styrene

2008

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The relationship between outer hair cell (OHC) loss and cochlear sensitivity is still unclear, because in many animal models there exist surviving but dysfunctional OHCs and also injured/dead inner hair cells (IHC). Styrene is an ototoxic agent, which targets and destroys OHCs starting from the third row to the second and first rows depending on the exposure level. The remaining cells may be less affected. In this experiment, rats were exposed to styrene by gavage at different doses (200-800 mg/kg/day) for varying periods (5 days/week for 3-12 weeks). An interesting finding was that the cochlear sensitivity was not affected in a few rats with all OHCs in the third row being destroyed by styrene. A further loss of OHCs was usually accompanied with a linear input/output (I/O) function of cochlear compound action potentials (CAP), indicating the loss of cochlear amplification. However, normal CAP amplitudes at the highest stimulation level of 90 dB SPL were often observed when all OHCs were destroyed, indicating normal function of the remaining IHCs. The OHC-loss/hearing-loss relation appeared to be a sigmoid-type function. Initially, styrene-induced OHC losses (<33%) did not result in a significant threshold shift. Then CAP threshold shift increased dramatically with OHC loss from 33% to 66%. Then, CAP threshold changed less with OHC loss. The data suggest a tri-modal relationship between OHC loss and cochlear amplification. That is, under the condition that all surviving OHCs are ideally functioning, the cochlear amplifier is not affected until 33% of OHCs are absent, then the gain of the amplifier decreases proportionally with the OHC loss, and at last the amplifier may fail completely when more than 67% of OHCs are lost.

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“…Styrene has been shown to be a more potent ototoxicant than toluene, and to have a synergistic effect when presented in concert with noise or ethanol. 52,53 Early human field studies assessing the effects of styrene on auditory function identified only minimal effects of the solvent on pure-tone thresholds. 54,55,56 More recently, the effects of styrene were investigated in male workers exposed in factories that produced plastic buttons or bathtubs.…”

Section: Styrenementioning

confidence: 99%

Health hazard evaluation report: HETA-2000-0110-2849, Human Performance International, Inc., Charlotte, North Carolina.

2001

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Combined effects of exposure to styrene and ethanol on the auditory function in the rat

Cited by 28 publications

References 31 publications

Effects of Alcohol and Noise on Temporary Threshold Shift in Guinea Pigs

Effects of Alcohol and Noise on Temporary Threshold Shift in Guinea Pigs

Relation between outer hair cell loss and hearing loss in rats exposed to styrene

Health hazard evaluation report: HETA-2000-0110-2849, Human Performance International, Inc., Charlotte, North Carolina.

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