title: Aroclor 1254 impairs the hearing ability of Xenopus laevis.
abstract: In this study we assessed the effects of chronic, dietary exposure of Aroclor 1254 (A1254) on the hearing of Xenopus frogs. We used the auditory brainstem response (ABR) to assay changes in hearing physiology; ABR thresholds, as well as latency-intensity and amplitude-intensity profiles of the initial positive (P1) and negative (N1) peaks were measured. Two groups of animals that received 50 ppm and 100 ppm of A1254 in their diet from 5 days post-fertilization through metamorphosis were compared to a control group that received untreated chow. The results showed significant threshold elevations in the 3-4 kHz range and significantly delayed peak latencies and reduced amplitudes at these frequencies in A1254 treated animals as compared to control animals. These findings indicate that A1254 selectively damages the high-frequency sensorineural hearing system associated with the basilar papilla of frogs. This preferential damage may be related to inherent differences in the vulnerability of the basilar versus amphibian papilla in the frog. The overall results of this study are also consistent with the reported A1254-induced auditory deficits in mammals indicating that the basilar papilla of the Xenopus frog may serve as an effective model for studying the effects of A1254 on the auditory system.
authors.affiliation: Department of Speech Pathology and Audiology, Western Michigan University, 1903 West Michigan Avenue, Kalamazoo, MI 49008-5355, USA. Bharti.Katbamna@wmich.edu
authors.forename: Bharti
authors.initials: B
authors.lastname: Katbamna
authors.forename: Anna Jelaso
authors.initials: AJ
authors.lastname: Langerveld
authors.forename: Charles F
authors.initials: CF
authors.lastname: Ide
mesh_terms: D000161:Acoustic Stimulation; D000284:Administration, Oral; D000704:Analysis of Variance; D000818:Animals; D013956:Antithyroid Agents / Q000008:administration & dosage / Q000633:toxicity; D001307:Auditory Perception / Q000187:drug effects; D020111:Chlorodiphenyl (54% Chlorine) / Q000008:administration & dosage / Q000633:toxicity*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D004785:Environmental Pollutants / Q000008:administration & dosage / Q000633:toxicity*; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects*; D006309:Hearing / Q000187:drug effects*; D034381:Hearing Loss / Q000139:chemically induced* / Q000503:physiopathology; D007814:Larva; D009925:Organ of Corti / Q000187:drug effects / Q000254:growth & development; D012684:Sensory Thresholds / Q000187:drug effects*; D036401:Toxicity Tests, Chronic; D014982:Xenopus laevis
chemical_list: D013956:Antithyroid Agents; D004785:Environmental Pollutants; D020111:Chlorodiphenyl (54% Chlorine)