Differences among white adipose tissue depots in mice

Abstract

Excess white adipose tissue (WAT) is widely associated with insulin resistance, type 2 diabetes (T2D) and cardiovascular disease (CVD). In fact, intra‐abdominal fat is better correlated with insulin resistance than subcutaneous fat. However, the physiological impact of adipose depot location is not well understood. Our goal was to investigate cellular and molecular differences between WAT depots. Cell sizes and proteomic profiles from subcutaneous (inguinal) and intra‐abdominal (mesenteric, epididymal and retroperitoneal) fat pads from C57BL6/J mice were analyzed. Proteomes resolved by two‐dimensional gel electrophoresis followed by mass spectrometry showed significant differences in proteins involved in glycolysis, energy production, lipid transport, stress resistance, cytoskeleton structure, and others. Some of these proteins showed significant correlations to plasma insulin, leptin and/or adiponectin levels. Mean adipocyte cross‐sectional area was measured by digital image analysis of paraffin embedded tissue and was highest in epididymal and lowest in inguinal and mesenteric fat. Together, these results show marked differences among WAT depots, even within intra‐abdominal fat. This and further studies will help clarify the depot‐specific characteristics and their influence on insulin resistance in an effort to establish new diagnostic and/or therapeutic targets for T2D and CVD.Supported in part by the State of Ohio's Eminent Scholar Program that includes a gift from Milton and Lawrence Goll, by NIH Grants DK075436‐01, AG019899‐06, 1P01AG031736‐01A1, by the Diabetes Research Initiative and the BioMolecular Innovation and Technology Partnership at Ohio University, and by AMVETS.