Adiponectin and adiponectin receptor-1 in patients with polycystic ovarian syndrome: Impact of insulin sensitization by metformin

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Background: Abdominal obesity, insulin resistance and hyperinsulinemia play a central role in the pathogenesis of polycystic ovarian syndrome (PCOS). Abdominal adipose tissue is a source of adiponectin. Metformin has been widely used in the treatment of PCOS and has been shown to improve the metabolic and hormonal disturbances of PCOS. Objective: The current study aimed to investigate the relationships between serum adiponectin and adiponec-tin receptor-1 (AdipoR1) with insulin resistance, hormonal variables, and anthropometric measures in patients with polycystic ovarian syndrome (PCOS), and to find the shortterm effect of metformin treatment on adiponectin and Adi-poR-1 levels in these patients. Patients and Methods: 38 PCOS patients and 14 age- and body mass index (BMI)-matched healthy controls were recruited. In all participants, BMI, waist circumference, serum levels of fasting glucose, insulin, adiponectin, AdipoR1, total testosterone, luteiniz-ing hormone (LH), and follicle stimulating hormone (FSH) were assessed. PCOS patients received metformin treatment (1500 mg/daily) for two menstrual cycles followed by measurement of all previous parameters. All subjects gave informed consent. Results: PCOS patients had higher waist circumference, fasting glucose, insulin, homeostasis model assessment of insulin resistance (HOMA-IR), testosterone, LH and LH/FSH ratio than did controls. In PCOS patients, adiponectin and AdipoR1 were lower than in controls, and both correlated negatively with waist circumference, insulin, and HOMA-IR (P=0.048, P=0.0003, P=0.0003, respectively for adiponectin and P=0.039, P=0.023, P=0.025, respectively for AdipoR-1). HOMA-IR followed by testosterone were independent predictors of adiponectin while HOMA-IR was an independent predictor of AdipoR1. Metformin decreased fasting glucose (P=0.003), insulin (P=0.042), HOMA-IR (P=0.006), testosterone (P=0.001), LH (P=0.0001) and LH/ FSH ratio (P=0.003) and increased adiponectin (P=0.014) and AdipoR1 (P=0.001) levels in PCOS patients. Conclusion: Reduced adiponectin and Ad-sipoR1 in PCOS patients is independently associated with insulin resistance and the improvement of insulin sensitivity by short-term metformin treatment results in increased adiponectin and AdipoR-l.