Effects of noise stress on thyroid gland histomorphology in adult rats

Abstract

OBJECTIVE: To analyze the effects of variable durations of loud noise stress on the histomorphology of the thyroid gland in adult rats. METHODS: This laboratory-based experimental study was conducted at the Anatomy Department, Army Medical College/National University of Medical Sciences, Rawalpindi, Pakistan, from January to December 2020. Thirty Sprague Dawley rats were divided into three groups: Control group A (no noise exposure), experimental group B (100 dB noise for 4 hours daily), and experimental group C (100 dB noise for 6 hours daily) for four months. At the end of the experiment, the rats were weighed, euthanized, and their thyroid glands removed. The glands were analyzed microscopically after Haematoxylin and Eosin staining, measuring the diameter and epithelial height of thyroid follicles. RESULTS: All rats remained healthy with no statistically significant differences in weight gain between the groups. The follicular epithelial height significantly increased in groups B (9.86±0.38 µm) and C (10.37±0.39 µm) compared to the control group A, (p-values <0.001 and 0.001, respectively). The follicular diameter significantly decreased in groups B (86.61±7.68 µm) and C (95.47±5.24 µm) compared to group A, (p-values <0.001 and 0.003, respectively. Microscopic examination revealed that experimental groups exhibited disrupted thyroid follicles and increased inflammatory infiltrates compared to controls. CONCLUSION: Exposure to variable durations of loud noise stress in adult rats leads to histomorphological changes in the thyroid gland, including increased follicular epithelial height and reduced follicular diameter. These findings are suggestive of potential hyperactivity of thyroid follicles in response to noise stress exposure.

Keywords

• thyroid gland
• diameter
• epithelium
• thyroid follicle
• noise
• stress
• stress, physiological
• thyroid nodule
• histomorphology