Adiponectin, a novel adipocyte-derived collagen-like protein, is the gene product of the adipose most-abundant gene transcript 1 (apM1), which has been considered to have anti-inflammatory and anti-atherogenic effects.

To characterize the relationship between adiponectin and leptin, the ob gene product, in normal-weight and obese women.

In this cross-sectional study, we measured fasting plasma adiponectin by ELISA, leptin concentrations by RIA, and related parameters such as blood pressure, body mass index (BMI), body fat mass, lipids, fasting blood glucose and insulin in 353 non-diabetic adult women with a wide range of BMI values.

Plasma adiponectin concentrations in women with the highest tertile of BMI (at least 25.0 kg/m²) were decreased compared with those in the middle (22.0–25.0 kg/m²) or lowest (<or=22.0 kg/m²) tertile of BMI (means+/-s.e.m.: 6.7+/-0.3 microg/ml compared with 8.6+/-0.4 microg/ml and 9.2+/-0.3 microg/ml; both P < 0.0001). Serum leptin concentrations in women with the highest tertile of BMI were increased compared with those in women in the middle or lowest tertile of BMI (13.2+/-0.4 ng/ml compared with 8.1+/-0.2 ng/ml and 5.2+/-0.2 ng/ml; both P < 0.0001). These relationships were similar after adjustment for BMI or body fat mass. Adiponectin was negatively correlated with serum leptin concentration, fasting immunoreactive insulin, calculated insulin resistance (homeostasis model assessment), BMI and body fat mass. These negative relationships became stronger after adjustment for BMI or body fat mass. In stepwise regression analyses, leptin was the significant independent variable for adiponectin, and adiponectin was also the significant independent variable for leptin before and after adjustment for BMI or body fat mass.

In this study, we found an inverse correlation between adiponectin and leptin in vivo.