Inhibitory effects of thymoquinone on hypothalamic aromatase and ghrelin gene expression in intact and diabetic rats

Background and Objective: Thymoquinone stimulates the activity of hypothalamic-pituitary-gonadal axis (HPG). Diabetes, ghrelin and aromatase are associated with decreased function of HPG axis. This study aimed to investigate the influence of thymoquinone on aromatase and ghrelin gene expression in intact and diabetic rats. Materials and Methods: Twenty male Wistar rats weighing 190-220 g were used. Diabetes type 1 was induced by alloxan. Saline or thymoquinone (10 mg/kg) was injected into intact or diabetic rats intraperitoneally for two weeks. One day after last injection, the hypothalamic samples were removed. Relative gene expression of aromatase and ghrelin was determined by RT-PCR method. Results: Thymoquinone did not alter the aromatase expressions in the healthy rats. However, it caused a marked decrease in ghrelin expression in healthy rats. The aromatase and ghrelin expression significantly reduced in the diabetic rats receiving thymoquinone in comparison with diabetic group. Conclusion: Thymoquinone may be a drug to improve decreased HPG axis activity of diabetic rats due to its inhibitory effects on aromatase and ghrelin upstream GnRH neurons.