Effects of Alcoholic Extract of Myrtus communis L. on the Hypothalamic-Pituitary-Thyroid Axis in Rats

Background: Myrtus communis leaves have the potential to affect thyroid hormone functions. Objectives: In this study, the effects of hydroalcoholic extract of M. communis on the hypothalamus-pituitary-thyroid axis and histological changes were studied. Materials and Methods: In this experimental study, 40 male rats were divided in 5 groups (n = 8): control, sham, and three experimental groups which received the extract of M. communis leaves in a minimal (0.75 mg/kg), Medium (1.5 mg/kg) and maximal amounts (3 mg/kg), respectively. At the end of the 15th day blood samples were collected to measure triiodothyronine (T3), thyroxine (T4) and thyroid-stimulating hormone (TSH) and to study thyroid gland tissue Results: Serum levels of T4 and TSH in groups receiving maximum dose of the extract showed a significant decrease compared to sham group (P < 0.05). Conclusions: It is probable that some compounds in the alcoholic extract of M. communis leaves may be cause changes in serum TSH concentration and thyroid hormones.