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Titolo:
THYROXINE AFFECTS PHYSIOLOGICAL AND MORPHOLOGICAL DEVELOPMENT OF THE EAR
Autore:
FREEMAN S; CHERNY L; SOHMER H;
Indirizzi:
HEBREW UNIV JERUSALEM,HADASSAH MED SCH,DEPT PHYSIOL,POB 12272 IL-91120 JERUSALEM ISRAEL TEL AVIV UNIV,FAC LIFE SCI,DEPT ZOOL RAMAT AVIV ISRAEL
Titolo Testata:
Hearing research
fascicolo: 1-2, volume: 97, anno: 1996,
pagine: 19 - 29
SICI:
0378-5955(1996)97:1-2<19:TAPAMD>2.0.ZU;2-5
Fonte:
ISI
Lingua:
ENG
Soggetto:
PRODUCT OTOACOUSTIC EMISSIONS; ACOUSTIC DISTORTION PRODUCTS; RAT CEREBELLAR CORTEX; 2 DISCRETE SOURCES; OUTER HAIR-CELLS; POSTNATAL-DEVELOPMENT; EARLY HYPOTHYROIDISM; BASILAR-MEMBRANE; ETHACRYNIC-ACID; NEONATAL RATS;
Keywords:
AUDITORY NERVE BRAIN-STEM RESPONSE; OTOACOUSTIC EMISSION; DISTORTION PRODUCT; DEVELOPMENT; RAT;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Science Citation Index Expanded
Citazioni:
43
Recensione:
Indirizzi per estratti:
Citazione:
S. Freeman et al., "THYROXINE AFFECTS PHYSIOLOGICAL AND MORPHOLOGICAL DEVELOPMENT OF THE EAR", Hearing research, 97(1-2), 1996, pp. 19-29

Abstract

The onset and development of distortion product otoacoustic emissions(DPE) representing cochlear amplifier activity were studied in neonatal hyperthyroid (n = 10) and control (n = 10) rat pups. These were compared to the onset and development of auditory nerve-brainstem evoked responses (ABR) representing overall cochlear function, and to morphological development of the ear. DPEs were recorded at an earlier postnatal age to high (8 kHz) frequencies and progressed to lower (3 kHz) frequencies with age. ABRs to high-intensity clicks were recorded at least 2 days before DPEs, although DPE onset at 8 kHz preceded adult-likeABR thresholds. Both ABR and DPEs appeared earlier in the hyperthyroid rats. Histological evidence showed earlier morphological developmentof the ear in these animals. ABR thresholds and DPE amplitudes matured at a slower rate in the experimental group despite their earlier onset. There was no difference in ABR and DPE thresholds between adult hyperthyroid and control rats. However, in the experimental group, DPEs had smaller amplitudes to high (70 dB SPL) and to low (50 dB SPL) stimulus intensities at low frequencies. Hence, despite thyroxine-injectedrat pups having earlier onset of auditory structure and function (lower ABR thresholds and earlier functioning active cochlear amplifier), it appeared that neonatal hyperthyroidism affected the later state of the cochlea, such that DPEs, especially to low-frequency stimuli, weredepressed during and after maturation.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 04/12/20 alle ore 19:55:40