Improvement of Kidney Yang Syndrome by Icariin through Regulating Hypothalamus-Pituitary-Adrenal Axis

Objective: To investigate whether Epimedium brevicornu Maxim (EB) and icariin could exert their protective effects on hydrocortisone induced (HCI) rats by regulating the hypothalamus-pituitary-adrenal (HPA) axis and endocrine system and the possible mechanism. Methods: Male 10-week-old Sprague Dawley (SD) rats were allotted to 6 groups (A-F) with 12 each, group A was injected normal saline (NS) 3 mL/kg.day intraperitoneally, group A and B were given NS 6 mL/kg.day by gastrogavage, group B-F were injected hydrocortisone 15 mg/kg intraperitoneally, group C and D were given EB 8 or 5 g/(kg.day) by gastrogavage, group E and F were given icariin 25 or 50 mg/(kg.day) by gastrogavage. Gene expressions of hypothalamus corticotropin releasing hormone (CRH) and pituitary proopiomelanocortin (POMC) were detected by reverse transcription-polymerase chain reaction (RT-PCR), and protein of pituitary POMC by Western-blot. Results: The serum T4, testosterone, cortisol and POMC mRNA expression were increased after treatment with EB or icariin in HCI rats, the serum CRH and the hypothalamus CRH mRNA expression released from hypothalamus corticotropin decreased compared with group B (P<0.05). The treatment with only icariin increased serum adrenocorticotropic hormone (ACTH) compared with group B (P<0.05). Conclusion: EB and icariin might be therapeutically beneficial in the treatment of HCI rats through attuning the HPA axis and endocrine system which was involved in the release of CRH in hypothalamic, and the production of POMC-derived peptide ACTH in anterior pituitary, the secretion of corticosteroids in adrenal cortex.