Impact of erythropoietin and myoinositol versus metformin on insulin resistance in a rat model of polycystic ovary syndrome

Therapeutic exploration of polyherbal formulation against letrozole induced PCOS rats: A mechanistic approach

Objective

This study aimed to develop an effective alternative medicine with multi potential herbs against polycystic ovarian syndrome (PCOS) in rats induced by letrozole treatment.

Materials and method

Polyherbal syrup was prepared with a combination of S. asoca bark, G. sylvestre leaves, P. daemia aerial parts, C. zeylanium stem bark, C. bonduc seeds, and W. somnifera roots ethanolic extract. In vitro cell viability study, adenosine monophosphate-activated protein kinase (AMPK), and glucose transporter 4 (GLUT4) gene expression assay were carried out on the Chinese Hamster Ovarian (CHO) cell line. For the PCOS induction letrozole (1 mg/kg p. o.) was given for 21 consecutive days. The PCOS induction was confirmed by measuring estrus irregularity, insulin resistance by oral glucose tolerance test (OGTT), and hyperandrogenism by measuring serum total testosterone level 21 days after completion of letrozole treatment. After induction of PCOS, metformin (155 mg/kg p. o.), and polyherbal syrup (100 mg/kg, 200 mg/kg, and 400 mg/kg p. o.) were administered for further 28 days. The treatment efficacy was measured by measuring serum lipid profile, fasting insulin level, sex hormones level, ovarian steroidogenic enzymes, ovarian tissue insulin receptor, AMPK, and GLUT4 protein expression levels, and histomorphological studies. The post-treatment effect was confirmed by reproductive performance studies.

Results

Letrozole-induced PCOS rats showed significant estrus irregularity, abnormal sex hormones levels, and hyperandrogenism indicated by showing increased free androgenic index and decreased sex hormones binding globulin (SHBG) level. The insulin resistance in PCOS rats was indicated by increased fasting glucose levels with impaired glucose clearance in the OGT test. Homeostasis Model Assessment Index of Insulin Resistance (HOMA-IR) increased level, also decreases INSR, GLUT4, and AMPK mRNA expression in ovarian cells confirming the insulin resistance in PCOS rats. Ovarian histology in PCOS rats also showed many follicular cysts, atretic follicles, and the absence of corpus luteum. The administration of polyherbal syrup, in a dose-dependent manner, effectively restored these alterations. The treatment of polyherbal formulation 400 mg/kg possesses highly significant efficacy over the treatment of metformin in PCOS rats. It mainly acts by reducing peripheral and ovarian hyperandrogenism and improves insulin sensitivity via activating the insulin receptor and AMP-activated kinase-mediated transcription and translation of GLUT4 from the cytoplasm to the ovarian membrane improves glucose uptake and promotes the follicular development and ovulation. The higher fertility rate, delivery index, and survival of delivered pups confirm the broader and superior efficacy of PCOS. These beneficial actions are mainly attributable to the formulation's inclusion of the key secondary metabolites flavonoids and phytosterols. In conclusion, the prepared polyherbal syrup was found to be the safest and most effective alternative medicine for both endocrinal and metabolic complications of PCOS women.

CXCL13 and CXCR5 are upregulated in PCOS mice ovaries but downregulated following metformin administration

Polycystic ovary syndrome (PCOS) is becoming a common pathology among women, yet its pathogenesis remains enigmatic. The chemokine C-X-C motif ligand 13 (CXCL13) and its receptor type 5 (CXCR5) regulate inflammatory responses but their roles in PCOS remain unknown. Metformin is commonly administered to PCOS patients but its mechanism of action remains unclear. Thus, we aimed to determine the expression of CXCL13 and CXCR5 in the ovaries of PCOS mice and to evaluate the therapeutic effect of metformin on them. The study comprised four groups of mice: control, PCOS, PCOS plus metformin, and PCOS plus vehicle. CXCL13 and CXCR5 were found to be elevated in the ovarian tissues of the PCOS mice. Metformin reduced ovarian CXCL13 and CXCR5 expressions in the PCOS mice. Hence, CXCL13 and CXCR5 are potentially involved in PCOS pathogenesis; and metformin may help alleviate the symptoms of PCOS by inhibiting CXCL13 expression and actions.