Effects of total flavonoids from Eucommia ulmoides Oliv. leaves on polycystic ovary syndrome with insulin resistance model rats induced by letrozole combined with a high-fat diet.
Eucommia ulmoides Oliv. leaves are the dry leaves of Eucommia ulmoides Oliv. Modern studies have shown that Eucommia ulmoides Oliv. leaves and its extracts have many pharmacological effects, such as regulating hypothalamus pituitary ovary (HPO) axis function, estrogen like effects, correcting insulin resistance (IR), regulating lipids, and reducing weight, which are consistent with the clinical manifestations in polycystic ovary syndrome (PCOS) patients. PCOS patients often have HPO axis disorder, low estrogen, high androgen, high IR complication rate, and obesity. Previous preclinical studies have shown that total flavonoids from Eucommia ulmoides Oliv. leaves (TFEL) can improve the imbalance in sex hormone secretion in perimenopausal animal models by regulating the function of the HPO axis. Thus, it is important to understand if flavonoids are the active parts of Eucommia ulmoides Oliv. leaves that interfere with polycystic ovary syndrome with insulin resistance (PCOS-IR), and determine the regulatory role they play in sex hormones and IR?
Investigate the phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT) signaling pathway in the ovary and kisspeptin/insulin like growth factor/leptin receptor1/androgen receptor (Kiss1/IGF-1/LEPR/AR) in the HPO axis to determine the mechanism of TFEL intervention in a rat model of PCOS-IR model rats.
A rat model of PCOS-IR was established using a high-fat diet (49 d) combined with letrozole (1 mg/kg·d, for 28 d). Then, metformin (300 mg/kg·d) and TFEL (220 mg/kg·d, 110 mg/kg·d, and 55 mg/kg·d) were administered continuously for 21 days. At the end of the experiment, samples were taken and the related indexes were measured.
TFEL reduced the body weight, Lee's index, ovarian index, ovarian area and ovarian volume, increased serum E2, SHBG levels and ISI, decreased serum levels of T, LEP, INS, and FBG (whole blood), and reduced the HOMA-IR in rats with PCOS-IR. TFEL downregulate Kiss1, IGF-1, and AR in the arcuate nucleus of hypothalamus, and upregulate Kiss1, downregulate IGF-1 and AR in the pituitary gland, and upregulate Kiss1, downregulate IGF-1, LEPR, and AR in the ovary of rats with PCOS-IR. TFEL could downregulate p-IRS-1Ser307, upregulate IRS-1, p-IRS-1Tyr895, PI3Kp85α, p-PI3Kp85α, AKT, p-AKT, and GLUT4 in the ovary, and ameliorated histopathological changes in the ovary and pancreas of rats with PCOS-IR.
TFEL can inhibit ovarian hyperplasia, regulate disorders of glucose and lipid metabolism and improve the secretion of sex hormones, by regulating the expression of PI3K/AKT signaling pathway-related proteins in the ovary and Kiss1/IGF-1/LEPR/AR in the HPO axis.
Peng MF
，Tian S
，Song YG
，Li CX
，Miao MS
，Ren Z
，Li M
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Liuwei Dihuang Pills alleviate the polycystic ovary syndrome with improved insulin sensitivity through PI3K/Akt signaling pathway.
Polycystic ovary syndrome (PCOS) is a complex gynecological endocrine disease commonly occurred in women of childbearing age. The main hallmark of PCOS includes elevated androgen production and insulin resistance (IR). Liuwei Dihuang Pills (LWDH Pills), a commonly prescribed traditional Chinese medicine (TCM) is widely used as a tonic prescription to treat diabetes, female menopause syndrome and other symptoms with'Kidney-Yin' deficiency. It has been reported the effects LWDH pills on PI3K/Akt signaling pathway in T2DM treatment. Recent studies have also indicated that the treatment of menopausal syndrome may be associated with the ovarian sexual hormone levels regulated by LWDH pills to alleviate female infertility. However, its potential benefits on PCOS have not been fully elucidated.
The primary aim of this study was to investigate the alterations of PI3K/Akt pathway in polycystic ovary syndrome-insulin resistance (PCOS-IR) progression induced by letrozole combined with high fat diet (HFD) and then to explore the detailed mechanism of LWDH Pills to alleviate PCOS.
The female Sprague-Dawley rats were continuously treated with letrozole (p.o administration at 1 mg kg-1·day-1) and HFD for 21 days to establish the PCOS-IR model. Concurrently, metformin (200 mg kg-1·day-1) or LWDH Pills was orally administrated (1.2 or 3.6 g kg-1·day-1) to intervene disease progression. The ovarian pathology was evaluated by HE (hematoxylin-eosin) staining. The serum sexual hormones, follicle stimulating hormone (FSH), luteinizing hormone (LH), estradiol, testosterone, progesterone and fasting insulin (FINS) were determined by radioimmunoassay. The protein expressions of IRS-1, PI3Kp85α, Akt and FoxO1a were analyzed by western blotting, while the mRNA levels of follicle-stimulating hormone receptor (FSHR) and Cyp19a1 in ovarian tissue were measured by qPCR.
The upregulated phosphorylation of IRS-1 (S307), down-regulated phosphorylation of PI3Kp85α, Akt, and FoxO1a were significantly reversed by LWDH Pills (3.6 g kg-1·day-1) in PCOS-IR rats with up-regulated mRNA levels of FSHR and Cyp19a1 in ovary. Also, the index of insulin resistance was gradually adjusted to normal by LWDH Pills. The serum levels of FSH, estradiol, progesterone levels were significantly raised while LH, testosterone were reduced. The ovarian polycystic changes were alleviated while the atresia follicles were reduced.
LWDH Pills therapy obviously improved the ovarian polycystic pathogenesis and regained the development of follicles via upregulating Cyp19a1, alleviated insulin resistance through acting on PI3K/Akt signaling pathway. These findings have provided scientific evidence for LWDH Pills to treat PCOS.
Qiu Z
，Dong J
，Xue C
，Li X
，Liu K
，Liu B
，Cheng J
，Huang F
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