Alpha lipoic acid attenuates radiation-induced thyroid injury in rats

• Published in: PloS one Vol. 9; no. 11; p. e112253
• Main Authors: Jung, Jung Hwa, Jung, Jaehoon, Kim, Soo Kyoung, Woo, Seung Hoon, Kang, Ki Mun, Jeong, Bae-Kwon, Jung, Myeong Hee, Kim, Jin Hyun, Hahm, Jong Ryeal
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 17.11.2014; Public Library of Science (PLoS)
• Subjects: Acids; Alpha rays; Animal tissues; Animals; Antioxidants; Antioxidants - administration & dosage; Antioxidants - pharmacology; Biomedical research; Cytokines; Cytokines - blood; Cytokines - metabolism; Cytotoxicity; Diabetes; Diabetic neuropathy; Disease Models, Animal; Drug dosages; Exposure; Fibrosis; Follicles; Free radicals; Growth factors; Head and neck; Hypothyroidism; Immunoreactivity; Infiltration; Inflammation; Injury prevention; Interleukin 6; Internal medicine; Irradiated; Irradiation; Lipoic acid; Lymphocytes T; Male; Medicine; Medicine and Health Sciences; Nuclear accidents & safety; Oxidative stress; Oxidative Stress - drug effects; Pretreatment; Radiation; Radiation (Physics); Radiation dosage; Radiation effects; Radiation injuries; Radiation Injuries - drug therapy; Radiation Injuries - metabolism; Radiation Injuries - pathology; Radiation Injuries, Experimental; Radiation therapy; Radiation-Protective Agents - administration & dosage; Radiation-Protective Agents - pharmacology; Rats; Research and Analysis Methods; Rodents; Science; Studies; T cells; Thioctic Acid - administration & dosage; Thioctic Acid - pharmacology; Thyroid; Thyroid gland; Thyroid Gland - drug effects; Thyroid Gland - pathology; Thyroid Gland - radiation effects; Transforming growth factors; Tumor necrosis factor-α; Tumors; α Radiation
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0112253

Exposure of the thyroid to radiation during radiotherapy of the head and neck is often unavoidable. The present study aimed to investigate the protective effect of α-lipoic acid (ALA) on radiation-induced thyroid injury in rats. Rats were randomly assigned to four groups: healthy controls (CTL), irradiated (RT), received ALA before irradiation (ALA + RT), and received ALA only (ALA, 100 mg/kg, i.p.). ALA was treated at 24 h and 30 minutes prior to irradiation. The neck area including the thyroid gland was evenly irradiated with 2 Gy per minute (total dose of 18 Gy) using a photon 6-MV linear accelerator. Greater numbers of abnormal and unusually small follicles in the irradiated thyroid tissues were observed compared to the controls and the ALA group on days 4 and 7 after irradiation. However, all pathologies were decreased by ALA pretreatment. The quantity of small follicles in the irradiated rats was greater on day 7 than day 4 after irradiation. However, in the ALA-treated irradiated rats, the numbers of small and medium follicles were significantly decreased to a similar degree as in the control and ALA-only groups. The PAS-positive density of the colloid in RT group was decreased significantly compared with all other groups and reversed by ALA pretreatment. The high activity index in the irradiated rats was lowered by ALA treatment. TGF-ß1 immunoreactivity was enhanced in irradiated rats and was more severe on the day 7 after radiation exposure than on day 4. Expression of TGF-ß1 was reduced in the thyroid that had undergone ALA pretreatment. Levels of serum pro-inflammatory cytokines (TNF-α, IL-1ß and IL-6) did not differ significantly between the all groups. This study provides that pretreatment with ALA decreased the severity of radiation-induced thyroid injury by reducing inflammation and fibrotic infiltration and lowering the activity index. Thus, ALA could be used to ameliorate radiation-induced thyroid injury.