The Role of IntraNasal Insulin in Regulating HepaTic Lipid COntent in HUMANS

Non-alcoholic fatty liver disease (NAFLD) is a common human liver pathology, closely associated with the obesity pandemic and insulin resistance. In the insulin resistant state the liver remains sensitive to pro-lipogenic signals of insulin, which further promote lipid accumulation. Secretion of very-low-density-lipoproteins (VLDL), the main carriers of triglycerides (TG) in the plasma, is the principal pathway for the liver to mobilize and dispose of lipids. Thus, hepatic TG export must not be too low in order to prevent steatosis. Our preliminary data from animal experiments suggest that enhanced brain insulin signaling promotes hepatic VLDL secretion, and reduces lipid accumulation in the liver. It remains to be tested whether other insulin sensitive tissues, such as the myocardium or the skeletal muscle, are also affected. In humans, neuropeptides, including insulin, can be delivered to the brain via an intranasal (IN) route of administration, without causing relevant systemic side effects. Therefore, we hypothesize that by enhancing brain insulin signaling using chronic IN insulin administration hepatic TG export increases and prohibits lipid accumulation in the liver and other insulin sensitive tissues, such as the myocardium and the skeletal muscle.