Objective: To investigate leptin mRNA expressions in subcutaneous (SC) and omental (OM) adipose tissues of patients with nonalcoholic fatty liver disease (NAFLD), and their relationships with insulin resistance (IR), blood leptin, blood triglyceride, total blood cholesterol, blood glucose, body weight index and waist-hip ratio.
Methods: SC and OM adipose tissues were obtained from 10 obese and 11 nonobese NAFLD patients and from 11 obese and 13 nonobese patients without NAFLD, who served as controls. Leptin mRNA expression levels in the subcutaneous and omental adipose tissues were measured using SYBR Green I quantitative real-time PCR. IR was estimated using homeostasis assessment (HOMA). The levels of plasma leptin and insulin were measured using ELISA.
Results: The relative mRNA expression of leptin, HOMA-IR and blood leptin levels in NAFLD differed significantly from those of the controls (P < 0.05). The leptin/GAPDH ratio of the obese and nonobese NAFLD and control cases were 1.32 +/- 0.12, 0.99 +/- 0.05, 1.10 +/- 0.09, 0.87 +/- 0.13 respectively. The expression levels of SC and OM adipose leptin mRNA in NAFLD patients were positively correlated with HOMA-IR (r=0.72, P < 0.05), blood leptin (r=0.69, P < 0.05), blood triglyceride (r=0.32, P < 0.05), body weight index (r=0.57, P < 0.05) and waist-hip ratio (r=0.50, P <0.05).
Conclusion: The primary reason for high levels of blood leptin is high leptin mRNA expression in adipose tissues; in both obese and nonobese patients with NAFLD; high levels of blood leptin and the leptin mRNA expression in adipose tissues and IR exist. These findings suggest that leptin resistance exists in patients with NAFLD and leptin resistance is positively correlated with NAFLD, the same as in insulin resistance.