ArticlesToluene and Styrene Intoxication Route in the Rat Cochlea
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Animals
Male Long-Evans rats (450 g) were purchased from a local supplier (Janvier Laboratories). The rats (n = 32) were housed in individual cages (350 × 180 × 184 mm) 1 month before the start of the experiments. Food (UAR Cie France; A04 10) and tap water were available ad libitum. Temperature in the animal quarters was 22 ± 1°C and the humidity ranged from 50% to 55%. Fluorescent lights were on from 0700 to 1900 h. The investigators followed the Guiding Principles in the Use of Animals in
Toluene
The toluene concentrations obtained in the different tissues are presented in Table 1. Toluene was detected in blood, brain (Part A, B), auditory nerve, or cochleae, but not in the fluids of the treated animals. There is no significant difference [1.02 μg/g (−2.94, 4.99), t14 = 0.55, p = 0.59] in toluene between Part A and B. As a result, the comparison between brain and other tissue will be done with the average between A and B [47.61 μg/g (42.3, 52.92)]. The difference of toluene [21.48 μg/g
Discussion
The solvent concentrations found in brain are higher than those in blood, as previously mentioned by Withey (26) and Benignus et al. (3). In the present study, the toluene concentrations are 47.6 μg/g in brain and 26.1 μg/g in blood, which are similar to the values reported by Kishi et al. (13), 45 and 30 μg/g, 1 h after 4-h toluene exposure to 2000 ppm. Due to the discrepancies between the experimental protocols, it is risky to compare our styrene results with the small amount of data reported
Acknowledgements
The authors thank Dr. L. Fechter and T. Morata for helpful critiques of the manuscript, C. Barthélémy (N/PE) and P. Bonnet (N/TIE) for their technical assistance, and extend special thanks for M. Grzebyk, who performed the statistical analyses.
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