Role of Adipokines in Controlling Insulin Signaling Pathways in Type-2 Diabetes and Obesity. Current and Future Perspectives

Adipose cells produce several types of cytokines, known as adipokines, which influence a variety of endocrine signaling pathways. Specifically, several adipokines have been proposed to play a vital role in regulating insulin signaling pathways within various tissues in the body and may thus provide a molecular link between obesity and type 2 diabetes mellitus (type-2 DM). Adiponectin and leptin adipokines have been demonstrated to improve insulin sensitivity, while other adipokines such as resistin, tumor necrosis factor-α (TNF-α), and interleukin-6 (IL-6) have been evidenced to induce insulin resistance. The low-grade chronic inflammation and greater adipose deposition accompanied by obesity may lead to dysregulation in the production and secretion of adipokines, thus introducing metabolic complications. In this mini review, we will highlight the findings on the role of adipokines in insulin sensitivity/resistance in an effort to better understand the mechanism of type-2 DM. Then, we will provide a perspective on the potential control of adipokine secretion by extracellular mechanical loading cue. This is based on the reported correlation between the whole body exercise and circulating adipokine level. The understanding of cellular level mechanism of the mechanical loading control of adipokine biology may provide a new and improved insight into the missing link among exercise, obesity, and type-2 DM.