Role of lipid-derived mediators in skeletal muscle insulin resistance.

Imbalance between nutritional intake and energy expenditure has been described to culminate in obesity, which predisposes to insulin resistance and type 2 diabetes mellitus. In such states of energy oversupply, excess amounts of lipids are available in tissues and circulation. Over the past years, an increasingly important role in development of skeletal muscle (SkM) insulin resistance has been attributed to lipids and impaired fatty acid metabolism. In this review, we reflect the current state of knowledge about the effects of various lipid-derived mediators on SkM insulin sensitivity. Furthermore, potential mechanisms underlying the biogenesis of intramyocellular ectopic lipid stores are discussed. Previously, a pivotal role was attributed to mitochondrial dysfunction. However, results of recent studies have suggested an important role for exercise deficiency, accompanied by decreased expression levels of peroxisome proliferator-activated receptor-γ coactivator-1α and subsequent, incomplete β-oxidation. Additionally, we summarize the implications of increased levels of lipid-derived endocannabinoids (ECs) for metabolic control in peripheral tissue and highlight the benefits of targeting the EC system.