Developmental exposure to Aroclor 1254 produces low-frequency alterations in adult rat brainstem auditory evoked responses.
Developmental exposure of Long-Evans rats to 0, 1, 4, or 8 mg/kg/day Aroclor 1254 (A1254) from Gestational Day 6 through Postnatal Day 21 produces an elevated behavioral threshold for a 1-kHz tone. Brainstem auditory evoked responses (BAERs) were assessed in a subset of these animals (about 1 year old) using filtered clicks at 1 (65 and 80 dB SPL), 4 (60 and 80 dB SPL), 16 (40 and 80 dB SPL), and 32 (40 and 80 dB SPL) kHz. Aroclor 1254 decreased BAER amplitudes at 1 and 4 kHz, but not at 16 or 32 kHz. A dose-related decrease in the baseline-to-peak P1A amplitude was observed for the 1-kHz (80-dB) stimulus. Doses of 1, 4, or 8 mg/kg/day A1254 decreased the peak-to-peak amplitude of both P1AN1 and P1BN1 for a 1-kHz (80-dB) stimulus. Doses of 4 and 8 mg/kg/day A1254 decreased the peak-to-peak amplitude of N1P2 and P2N2 for a 4-kHz (60-dB) or 1-kHz (80-dB) stimulus. At 8 mg/kg/day, A1254 also increased the latency of peak P4 at 1 kHz (65 dB). The decreases in peak P1A amplitudes are consistent with a dysfunction of the cochlea and/or auditory nerve. Together, the data confirm that developmental exposure of rats to A1254 produces a permanent low- to mid-frequency auditory dysfunction and suggest a cochlear and/or auditory nerve site of action.
Herr
D W
DW
National Health and Environmental Effects Research Laboratory, U.S. Environmental Protection Agency, Research Triangle Park, North Carolina, 27711, USA.
Goldey
E S
ES
Crofton
K M
KM
D000818:Animals; D001140:Aroclors / Q000633:toxicity*; D001307:Auditory Perception / Q000187:drug effects; D001831:Body Temperature / Q000187:drug effects; D020111:Chlorodiphenyl (54% Chlorine); D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects* / Q000502:physiology; D005260:Female; D008297:Male; D011247:Pregnancy; D011297:Prenatal Exposure Delayed Effects; D051381:Rats; D011930:Reaction Time / Q000187:drug effects
D001140:Aroclors; D020111:Chlorodiphenyl (54% Chlorine)