Abstract
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.
Highlights
Radiation therapy is used widely in the management of head and neck tumors, lymphomas and malignancies of the central nervous system
Another study demonstrated that administration of T4 during radiation exposure did not prevent hypothyroidism, the follow-up duration was insufficient to explain the preventive effect of thyroid tumors [14]. van Santen et al [15] demonstrated T4 didn’t protect against radiation-induced thyroid damage in rat model
The present study aimed to investigate the protective effect of a-lipoic acid (ALA) on radiation-induced thyroid injury in rats
Summary
Radiation therapy is used widely in the management of head and neck tumors, lymphomas and malignancies of the central nervous system. The radiation-susceptibility of the thyroid was increased with an elevated level of thyroid-stimulating hormone (TSH) in rats [12]. Based on this observation, studies for TSH suppression by Lthyroxine (T4) have been performed, with controversial results. Another study demonstrated that administration of T4 during radiation exposure did not prevent hypothyroidism, the follow-up duration was insufficient to explain the preventive effect of thyroid tumors [14]. Van Santen et al [15] demonstrated T4 didn’t protect against radiation-induced thyroid damage in rat model. No known drug has been shown to prevent radiation-induced thyroid damage. Further studies should be required for finding a new drug
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
