Background: PCOS is a common endocrine disorder that is associated with insulin resistance. Asprosin hormone level is changed with insulin resistance. Metformin is an effective treatment for improvement of ovulation in women with PCOS.

Aim of the study: To investigate the effect of metformin treatment on the changes in serum asprosin level in letrozole-induced PCOS in rats.

Materials and Methods: Three groups of 39 adult female albino rats were equally distributed. 1) Control group, rats were given 1% aqueous solution of carboxy methyl cellulose orally once daily for 11 weeks. 2) PCOS group, rats were administered letrozole at concentrations of 1 mg/kg BW dissolved in 1% CMC (1 ml/kg) orally once daily for 11 weeks. 3) PCOS + Metformin group, after induction of PCOS as in PCOS group for 3 weeks, rats were given metformin (50 mg/100 g BW in 0.05 ml of distilled water) orally once daily for 8 weeks. At the ending of the experiment, serum was extracted from collected blood for assessment of asprosin, sex hormones, glucose, insulin, lipid profile, SOD, TNF-α and IL-6 levels. Ovarian histopathological study was done.

Results: Metformin treatment caused a significant reduction in BMI, HOMA-IR and serum levels of asprosin, LH, testosterone, glucose, insulin and inflammatory cytokines with a significant increase in serum levels of FSH, Estradiol and SOD in female albino rats with PCOS in comparison with PCOS group.

Conclusion: Metformin treatment has insulin sensitizing; anti-inflammatory and antioxidant effects and it modulates disturbances in serum asprosin level in PCOS.