Increase in cochlear microphonic potential after toluene administration

Chemical exposure and hearing loss

“…67,68 For instance, N-methyl-D-aspartic acid, 69 δ-aminobutyric acid, glycine, 70 adenosyl triphosphate, 71 serotonin, 72 and nicotinic acetylcholine receptors 73 are all involved in CNS function and are sensitive to toluene. Recently, Lataye et al 74 and Maguin et al 75 showed that toluene could alter acetylcholine receptors and voltage-dependent Ca 2+ channels function in in vivo studies. Consequently, toluene, like most aromatic solvents, can affect the middle-ear acoustic reflex (the contraction of the middle-ear muscles that occurs in response to highintensity sound stimuli).…”

Occupational Chemical-Induced Hearing Loss

“…In animal models it is possible to control most of the variables; however, in humans many factors such as physical activity cannot be controlled experimentally. Lataye et al (2007) found a striking increase (4.2 dB) in the cochlear microphonic potential amplitude which was followed after left-carotid administration of toluene in experimental animals. An increase in the cochlear microphonic potential relates to the inhibition of the efferent control of the OHCs, and thus a lack of inhibition in the mechanical response of the OHCs to electrical signals.…”

“…An increase in the cochlear microphonic potential relates to the inhibition of the efferent control of the OHCs, and thus a lack of inhibition in the mechanical response of the OHCs to electrical signals. Lataye et al (2007) suggested that toluene inhibits the acetylcholine (Ach) receptors located in the efferent auditory system (medial olivocochlear bundle) that mediates the contraction of the OHCs in the cochlea. Similarly, Campo et al (2007) found that toluene may inhibit the Ach receptors of the efferent motor neurons located near the facial nerve nuclei that mediate the middle ear muscle systems.…”

Hazards to Hearing from Combined Exposure to Toluene and Noise in Rats

“…The mechanisms of toxicity of toluene and other aromatic organic solvents on the cochlea have not been clarifi ed, but recently a possible explanation of the potentiation by aromatic organic solvents of the effects of noise exposure has appeared. It has been shown that toluene may act as an antagonist of the auditory medial efferent system, thereby augmenting the acoustic energy absorbed by the cochlea in response to the noise exposure [50]. As toluene at high levels of exposure is defi nitely ototoxic to rats, several mechanisms may be involved in the effects of interactions between toluene and noise exposure, which has been observed both in the studies on rats and in human studies [47,48].…”

“…The 90-day study This part of the study was performed to elucidate the consequences of long-term, low-level exposure both IJOMEH 2008;21(1) 50 the level of primary tones fi xed (L1 = 60 db and L2 = 50 dB SPL). The DPOAE input/output curves (I/O curves) were assessed by measuring the amplitude of the CDP to varying levels of primary tones in 5-dB steps.…”