| Changes of the Olfactory Epithelium in Artificially Induced Hypothyroid Rats |
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Hyo Yeol Kim, Hun Jong Dhong, Seong Won Yoon, Hyun Jun Lim |
1Dapartment of Otorhinolaryngology and Head and Neck Surgery, Sungkuynkwan University School of Medicine, Samsung Medical Center, Korea. hidhong@smc.samsung.co.kr
2Dapartment of Otorhinolaryngology and Head and Neck Surgery, National Police Hospital, Korea.
3Dapartment of Otorhinolaryngology and Head and Neck Surgery, Hallm University, College of Medicine, Seoul, Korea. |
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| Abstract |
Background and Objectives
This study was performed to investigate, through immunohistochemical analysis, the thyroid hormone's effect on the olfactory receptor neurons of adult rats.
MATERIALS AND METHODS
Hypothyroidism was induced by adding reversible goitrogen propylthiouracil (PTU) to the rats' drinking water (30 mg/kg weight). Sprague-Dawly rats aged nine to ten weeks were divided into three groups : control, six weeks or PTU therapy, and 12 weeks of PTU therapy. Light microscopic investigation of the olfactory mucosa was conducted with an immunohistochemical stain to observe for proliferating cell nuclear antigen (PCNA) and protein genepeptide (PGP) 9.5.
Results
The rats in the experimental groups gained less weight compared with normal rats of the same age. Light microscopic examination revealed no statistically significant differences in the thicknesses of the olfactory epithelium and the numbers of cells among the three groups in H-E stains, but the ratio of PCNA(+) supporting cells decreased significantly with longer durations of PTU treatment. As PTU therapy continued, immunoreactivities to PGP 9.5 in olfactory receptor cells decreased remarkably. After 12 weeks of PTU treatment, no immunoreactivity was observed in the olfactory receptor cells.
Conclusion
These results indicate that the thyroid hormone is essential for maturation of the olfactory receptor neuron. |
| Key Words:
Olfactory epithelium;Hypothyroidism;Hyposmia;Immunohistochemistry;Neuronal maturation |
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