Association of abdominal obesity, insulin resistance, and oxidative stress in adipose tissue in women with polycystic ovary syndrome

Abstract

Objective: To study the expression of insulin signaling-related genes and oxidative stress markers in the visceral adipose tissue obtained from polycystic ovary syndrome (PCOS) patients and healthy control subjects and to investigate the relationships among abdominal obesity, insulin resistance, and oxidative stress at the tissue level.

Design: Case-control study.

Setting: University teaching hospital.

Patient(s): In total, 30 PCOS patients and 30 healthy control subjects, who underwent laparoscopic surgery, were included in the study.

Intervention(s): Abdominal obesity was defined based on waist circumference (WC). The homeostasis model index was used to assess insulin resistance (HOMA-IR).

Main outcome measure(s): Gene expression of glucose transporter 4 (GLUT4) and insulin receptor substrate 1 (IRS1) in visceral adipose tissue (VAT) and the parameters of oxidative stress, such as superoxide dismutase, enzyme glutathione reductase, and dimethylarginine, were measured, and the expression of protein oxidative damage product 3-nitro-tyrosine residues (nitrotyrosine) in VAT was identified with the use of immunohistochemistry.

Result(s): PCOS was associated with lower expression of GLUT4 and IRS1 and a higher level of oxidative stress in VAT, which was strongly correlated with WC and HOMA-IR. Presence of abdominal obesity further intensified the correlations observed in our measurements. The nitrotyrosine expression in VAT was stronger in PCOS patients.

Conclusion(s): The strong correlation of insulin resistance with oxidative stress at the VAT level suggests that local oxidative stress and abnormalities of insulin signaling in adipose tissue play critical roles in the pathogenesis of PCOS.

Keywords: Polycystic ovary syndrome (PCOS); abdominal obesity; insulin resistance; oxidative stress; visceral adipose tissue (VAT); waist circumference (WC).