Influence of Melissa officinalis methanolic extract on hyperthyroidism in a rat model

Background and objective Thyroid disease represents the most common endocrine abnormality in recent years. This study was conducted to evaluate the effect of Melissa officinalis methanolic extract (MME) on hyperthyroidism in a rat model. Materials and methods Hyperthyroidism was induced by daily subcutaneous injection of L-thyroxine (250 mu m/kg body weight) for 14 days. Total phenolic compounds in extract and the in-vitro antioxidant activity of extract were determined. Moreover, identification of methanolic extract component of Melissa officinalis leaves (MME) was done using liquid chromatography-mass spectrometry. After 30 days of MME treatments, blood samples were collected for further biochemical determinations. Liver and kidney were excised for the determination of oxidative stress markers. Thyroid gland was also removed for histopathological examination. Results Various thyroid hormones (total and free triiodothyronine, as well as total and free thyroxine) were seriously affected and increased significantly with hyperthyroidism induction. Significant increases in serum glucose, interleukin-6, and interleukin-8 were detected in hyperthyroid group compared with control values, whereas hemoglobin level has not changed. Compared with control group, hyperthyroidism-induced glutathione depletion and reduction in glutathione peroxidase activity in the liver and kidney tissues, with significant increase in the lipid peroxidation and nitric oxide levels. Upon treatment with MME, significant improvements in thyroid hormones and the other aforementioned parameters were achieved. MME succeeded also in ameliorating the histological picture of the thyroid gland. Conclusions Current results indicate that MME treatment counteracts the oxidative stress induced by L-thyroxine and protects the liver and kidney and regulates blood glucose in hyperthyroidism state. We suggest that MME treatment may be considered for therapeutic use for hyperthyroidism.