Investigating the impact of resveratrol on thyroid function, structure, and metabolic alterations in hyperthyroidism model: in vivo study

Abstract

Background: Thyroid diseases have effects on metabolism and inflammation. The mechanism of these effects is not clear. Recently, there are several reports suggesting this interrelation between adipocytokines and thyroid dysfunction. Resveratrol is a natural polyphenol with antioxidant, anti-inflammatory, and antiproliferative properties. Previous studies showed that resveratrol down-regulates the expression of the thyroid-stimulating hormone receptor (TSHR in the FRTL-5 rat thyroid cell line.
Objective: To investigate the effects of resveratrol alone and in combination with methimazole on the function and structure of the thyroid gland and metabolic alteration in hyperthyroid male rats induced by levothyroxine. Methods: Forty rats were divided randomly into five groups, each consisting of 8 male rats: Group-I (Healthy control): healthy rats receive 10% DMSO (5ml/kg) orally for two weeks and then continue for the next three weeks. Group-II (induction group): hyperthyroid-induced animals (received thyroxine 600µg/kg, in 10% DMSO) for two weeks, then 10% DMSO (5ml/kg) for the next three weeks, orally. GroupIII (standard therapy): hyperthyroid-induced animals (received thyroxine 600µg/kg, in 10% DMSO) for two weeks orally, then treated with standard drug (Methimazole 10mg/kg in 10%DMSO for the next three weeks, orally. Group-IV (resveratrol treatment group): hyperthyroidinduced animals (Received thyroxin 600µg/kg, in 10% DMSO) for two weeks orally, then treated intraperitoneally with Resveratrol (100 mg/kg, in 10% DMSO) for the next three weeks. Group-V (combination of resveratrol and methimazole): hyperthyroid-induced animals (received thyroxine-600µg/kg, in 10% DMSO) for two weeks orally, then treated intraperitoneally with Resveratrol (100mg/kg, in 10% DMSO) and (Methimazole 10mg/kg in 10%DMSO orally) for the next three weeks. On day 21, the rats were euthanized, and whole blood was collected to examine thyroid hormones (TSH, T3, and T4), sodium iodide symporter, and metabolic markers (glucose, cholesterol,
leptin, adiponectin), and the thyroid gland was harvested for histopathological examination. Results: Resveratrol cause significantly decrease the serum levels of thyroid hormones (T3, T4) and increase the serum levels of (TSH), Also, resveratrol cause a significant decrease in serum levels of (glucose, cholesterol, leptin) and increase the level of adiponectin. In addition, resveratrol show significant improvement in histological changes that are associated with hyperthyroidism. The use of combination therapy (resveratrol and methimazole) cause a greater reduction in thyroid hormones (T3, T4) than each one alone. Conclusion: resveratrol produces an antithyroid effect and show significant improvement in metabolic alteration and histological changes at 100 mg/kg in hyperthyroid male rats induced by levothyroxine. Combination therapy (methimazole and resveratrol) exhibit a greater reduction in levels of thyroid hormones (T3, T4) than each one alone.