The positive effect of black seed (Nigella sativa L.) essential oil on thyroid hormones in rats with hypothyroidism and hyperthyroidism

In our study, the effect of essential oil obtained from Nigella sativa L. (NSE) on thyroid hormones and antioxidant balance in hypothyroidism (HT) and hyperthyroidism (HP) models induced by propylthiouracil(PTU) and L-thyroxine(LT4), respectively, in rats were investigated for 4 weeks. NSE was administered by gastric gavage at a dose of 200 mg/kg body weight. In this study, 48 male Wistar albino rats with an average weight of 180-290 g and age 5-6 months were divided into eight groups, as follows: groups with HT, (1) control, (2) HT, (3) NSE, and (4) HT + NSE; groups with HP, (1) control, (2) HP, (3), and NSE (4) HP + NSE. As a result, we found that NSE administration increased total triiodothyronine (TT3) and decreased nitric oxide in HT + NSE. Besides, it decreased TT3 in HP + NSE and increased total antioxidant capacity. Our findings suggest that NSE may have beneficial effects on thyroid gland abnormalities owing to its antioxidant properties. Practical applications Essential oils derived from Nigella sativa L. seed contain many bioactive substances such as thymoquinone and cymene. This paper emphasizes the effect of NSE on thyroid hormone abnormalities and negative oxidative state that occurs in HT and HP models. The present study provides evidence of a positive effect of NSE particularly on TT3 levels in the HT and HP models. It can therefore be assumed that NSE could be used as a supportive natural alternative source to improve thyroid hormone levels and relieve increased oxidative stress.