Medical Lasers; Engineering, Basic Research, and Clinical Application  
Effect of Low-level Laser Therapy on Propylthiouracil-induced Hypothyroidism Model Mice: A Pilot Study
In Kwon Mun1,*, Won Sang Yoo2,*, Sang Joon Lee1, Phil-Sang Chung1, Seung Hoon Woo1
1Department of Otolaryngology-Head and Neck Surgery, Dankook University College of Medicine, Cheonan, Korea
2Department of Internal Medicine, Dankook University college of Medicine, Cheonan, Korea
Correspondence to: Seung Hoon Woo
Department of Otorhinolaryngology-Head and Neck Surgery, Dankook University School of Medicine, 201 Manghyang-ro, Dongnam-gu, Cheonan 31116, Korea Tel.: +82-41-550-1781
Fax: +82-41-550-7837

*These authors contributed equally to this study.
Received: October 27, 2020; Published online: December 22, 2020.
© Korean Society for Laser Medicine and Surgery. All rights reserved.

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Background and Objectives
Hypothyroidism is the most common endocrine disease. On the other hand, there is no treatment that can improve the thyroid function. Low-level laser therapy (LLLT) can improve the cellular activity. The effect of hypothyroidism is not obvious. This study examined the effects of LLLT on the thyroid gland function of a propylthiouracil (PTU)-induced hypothyroidism mouse model.
Materials and Methods
Twenty-five male ICR mice were distributed into five groups of five animals each: Negative control (none PTU animal) and positive control (PTU animal) of unirradiated animals, and three experimental groups with LLLT (3J, 6J, and 12J). Each mouse was exposed to a distinct dose of a 632-nm laser once a week for three rounds. The positive control group and three LLLT groups were induced into a hypothyroidism state by PTU administration. The animals’ thyroid-stimulating hormone and thyroxine levels were measured using an ELISA kit, and their thyroid tissue was harvested and analyzed after sacrifice at the end of the experiment. The hormone level and morphological changes in the tissue of the five groups were compared.
The thyroid hormone levels in the control group and LLLT groups were similar. On the other hand, the thyroid tissue of the LLLT groups showed some morphological changes that were similar to those of iodine deficiency thyroid.
LLLT did not affect the thyroid gland function in PTU-induced hypothyroidism mice.
Keywords: Hypothyroidism; Propylthiouracil; Low-level laser therapy; Mice

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