III.2.B.a. Adiponectin

It is produced in the adipose tissue, the muscle, the heart and the vascular endothelium.

Physiological blood level: 5-10 µg/ml.

Its main effects:

            It increases insulin sensitivity. Insulin resistance develops in the lack of adiponectin.

            It decreases the plasma Glu concentration. It decreases the production of Glu by the liver.

It regulates food intake.

            It increases fatty acid oxidation in the muscle and the liver.

It increases the level of anti-inflammatory cytokines (interleukin 10, IL-10 and interleukin 1, IL-1).

            It inhibits macrophages and decreases the adhesion of monocytes.

            It increases the production of nitric oxide (NO) by endothelial cells.

It inhibits the proliferation of endothelial smooth muscle cells induced by growth hormone (GH).

            It decreases the LDL level.

Stimulation: Insulin

Inhibition: Low levels of it are found in diabetes mellitus (DM) and obese patients. Its secretion is inhibited by β-agonists, glucocorticoids, interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α).

Its level correlates negatively with the body fat content, with the waist-hip ratio, with the fasting insulin level, with the insulin resistance, with the levels of leptin and TG and with the visceral and subcutaneous fat contents.