Central leptin and insulin administration modulates serum cytokine- and lipoprotein-related markers

In most obese patients there is an inflammatory state characterized by lipid abnormalities, hyperleptinemia and hyperinsulinemia. Objective. The objective was to identify mechanisms involved in leptin's role in the attenuation of the response to insulin using a proteomic approach. Material/Methods. We studied the serum proteomic profile of rats treated by central leptin infusion followed by an injection of insulin. We analyzed the relationship between these proteins and serum cytokine and apolipoprotein levels. Results. Out of 81 protein spots, intensity differences were found in 11, corresponding to 5 proteins: three isoforms of alpha 1 macroglobulin; three of haptoglobin and serum amyloid P component-precursor. All of these are acute-phase proteins involved in inflammation and are correlated with cytokine levels. Additionally, two apolipoprotein E and two apolipoprotein A1 isoforms were identified and were found to correlate with LDL and HDL. Conclusions. Our results indicate that increased leptin and insulin levels change these circulating proteins, thus promoting systemic inflammation and changing lipid metabolism. (C) 2012 Elsevier Inc. All rights reserved.