ObjectiveTo explore the regulation of hypothalamic-pituitary-gonadal （HPG） axis by modified Erxian decoction in rats with perimenopausal syndrome （PMS） and to further analyze the expression of proteins related to the silent information regulator 1 （SIRT1）/hypothalamic kisspeptin （Kisspeptin）/gonadotropin-releasing hormone （GnRH） signaling pathway in the arcuate nucleus region （ARC） of the hypothalamus， so as to reveal the potential target of action and molecular biological mechanism of modified Erxian decoction for the treatment of perimenopausal syndrome.MethodsAn animal model was established via the incomplete castration method， with successful modeling confirmed by the exfoliated cervical cell smear method. The 48 rats were divided into six groups based on the randomization principle after successful modeling， including a sham operation group， a model group， an estradiol valerate group （0.09 mg∙kg^-1∙d^-1）， high-， medium-， and low-dose modified Erxian decoction groups （7.614， 3.807，1.903 5 g∙kg^-1∙d^-1）， with 8 rats in each group. The estradiol valerate group and the high-， medium- and low-dose modified Erxian decoction groups were continuously administered by gavage for 28 days， and the indicators were detected 24 hours after the last administration. Body weights and uterine indices were measured. The pathological changes of the uterus were observed by hematoxylin-eosin （HE） staining. Enzyme-linked immunosorbent assay （ELISA） was performed to measure the levels of estradiol （E₂）， follicle-stimulating hormone （FSH）， luteinizing hormone （LH）， and gonadotropin-releasing hormone （GnRH）. Real-time quantitative polymerase chain reaction （Real-time PCR） and Western blot were used to determine the expression levels of SIRT1， Kisspeptin， kisspeptin receptor （GPR54）， and GnRH in the ARC region of the hypothalamus and gonadotropin-releasing hormone receptor （GnRH-R） in pituitary.ResultsCompared with the sham operation group， rats in the model group had a significantly increased body weight （P0.01）， reduced wet weight and index of uterus （P0.01）， endometrial thinning or atrophy， glandular atrophy， and a decreasing number of glands. Additionally， serum levels of E₂ and the expression of SIRT1 in the ARC region of the hypothalamus significantly decreased （P0.01）. Serum levels of FSH， LH， and GnRH， the expression of Kisspeptin， GPR54， and GnRH in the ARC region of the hypothalamus， and GnRH-R in pituitary significantly increased （P0.01）. Compared with the model group， the estradiol valerate group and the high-， medium-dose modified Erxian decoction groups had significantly reduced body weight， serum levels of FSH， LH， and GnRH， and expression of Kisspeptin， GPR54， and GnRH in the ARC region of the hypothalamus and GnRH-R in pituitary （P0.05， P0.01） and significantly increased wet weight and index of uterus， serum level of E₂， and expression of SIRT1 in the ARC region of the hypothalamus （P0.05， P0.01）. In addition， they showed thickened endometrium， increased number of endometrial glands， and improved glandular atrophy.ConclusionModified Erxian decoction regulates the function of the HPG axis through multi-targets， and its mechanism of action may be related to the up-regulation of the expression of SIRT1 in the ARC region of the hypothalamus， the inhibition of the over-activation of the Kisspeptin/GnRH signaling pathway， the regulation of the expression of GnRH-R in the pituitary， the restoration of secretion balance of gonadotropins， and the elevation of the estrogen level. This study provides an experimental basis for the interpretation of the scientific connotation of modified Erxian decoction in the treatment of perimenopausal syndrome and a theoretical reference for the development of a novel therapeutic strategy based on the SIRT1/Kisspeptin/GnRH pathway.

modified Erxian decoction;perimenopausal syndrome;hypothalamic-pituitary-gonadal axis;silent information regulator 1/hypothalamic kisspeptin/gonadotropin-releasing hormone （SIRT1/Kisspeptin/GnRH） pathway