Abstract
Objective:
Congenital hypothyroidism is well known to impair auditory development and function. However, the effect of acquired hypothyroidism, particularly regarding its duration, has not been clearly defined. Data investigating the relationship between prolonged hypothyroidism and hearing remain scarce. This experimental study aimed to evaluate the impact of different durations of hypothyroidism on hearing function and cochlear morphology in Wistar albino rats.
Materials and methods:
Four groups were established, each consisting of at least 8 Wistar albino rats. The groups included a control group and 3 hypothyroid groups exposed to 6-n-propyl-2-thiouracil (PTU) for 15, 30, and 45 days, respectively. PTU was administered intraperitoneally on a daily basis. Auditory evaluation was performed using otoacoustic emission (OAE) and auditory brainstem response (ABR) testing before and after the experimental period. Biochemical confirmation of hypothyroidism was obtained through measurement of serum T4 and TSH levels, collected from intracardiac blood samples prior to sacrifice. Additionally, cochlear tissue was examined histopathologically to assess possible structural alterations.
Results:
ABR analysis revealed that the 15-, 30-, and 45-day hypothyroid groups exhibited increased auditory thresholds and prolonged wave latencies compared with baseline values (P < .05). Intergroup comparisons demonstrated significant differences in latency values across all groups (P < .05). OAE responses also showed reduced amplitudes in hypothyroid animals. Histopathological evaluation indicated marked structural changes in the cochlea in all hypothyroid groups when compared to controls (P < .05), consistent with the electrophysiological findings.
Conclusion:
Experimentally induced hypothyroidism adversely affects auditory function in a duration-dependent manner. The condition was found to impair both ABR and OAE outcomes, accompanied by histopathological changes in cochlear tissue. These findings confirm that thyroid hormones play a crucial role in preserving auditory physiology, and prolonged hypothyroidism may progressively disrupt hearing at both functional and structural levels.
Get full access to this article
View all access options for this article.
References
Supplementary Material
Please find the following supplemental material available below.
For Open Access articles published under a Creative Commons License, all supplemental material carries the same license as the article it is associated with.
For non-Open Access articles published, all supplemental material carries a non-exclusive license, and permission requests for re-use of supplemental material or any part of supplemental material shall be sent directly to the copyright owner as specified in the copyright notice associated with the article.
