Adipokines as Novel Links between Obesity and Insulin Resistance

At an adipobiological level, obesity and insulin resistance have been better elucidated in recent years. However, the molecular factors which upregulate insulin resistance phenotype in obesity are still unclear. Adipocytes and nonadipocytes of adipose tissue are increasingly recognized as endocrine and paracrine cells producing numerous signaling proteins, collectively termed adipokines. Along with their implications for various biological functions, adipokines profoundly influence insulin sensitivity and glucose metabolism. Furthermore, the insulin-sensitizing drugs thiazolidinediones as well as insulin resistance-inducing hormones, including β-adrenergic agonists, insulin, glucocorticoids, and growth hormone, mediate, at least in part, their effects via differential regulation of adipokines. Here we present a state-of-the-art focusing on adiponectin, IL-6, leptin, TNF-α , resistin, MCP-1 (CCL2), PAI-1, SPARC (osteonectin), visfatin, vaspin, RBP-4, and NGF. Further studies in adipokine-targeted pharmacology may reveal many potential targets for anti-obesity and anti-diabetic drug development.