Adipose Tissue Dynamics: Cellular and Lipid Turnover in Health and Disease

Figures

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  Figure 1. WAT distribution in humans and mice. Comparison between the distribution patterns of WAT in humans and mice highlighting the anatomical similarities and differences between the two species. (A) Schematic representation of WAT distribution in humans highlighting the major depots, such as vWAT surrounding internal organs (1, omental; 2, mesenteric; 3, retroperitoneal; 4, perirenal; 5, perigonadal; 6, pericardial) and scWAT located beneath the skin (7, gluteofemoral; 8, upper body subcutaneous; 9, abdominal subcutaneous). (B) WAT distribution in mice, showing vWAT located in the abdominal region (1, perigonadal; 2, mesenteric; 3, retroperitoneal) and scWAT situated under the skin (4, anterior subcutaneous; 5, interscapular; 6, inguinal).

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  Figure 2. WAT dynamics determine metabolic health. Lipid and cellular turnover in WAT determine the organ size. In situations of excess energy availability (A), adipocytes actively take up lipids and store the surplus energy as TAG, while the removal of lipids from adipocytes is minimal. Consequently, the average age of TAG within the adipocytes increases, leading to an overall increase in body weight and fat mass. Recruitment of adipocyte progenitor cells to generate new adipocytes is believed to meet the energy storage demands primarily in childhood, but it is unclear whether this mechanism persists during adulthood. On the other hand, in situations of energy deficit (B), lipid uptake by adipocytes decreases, while the removal of lipids increases. As a result, adipocyte size decreases and total body fat mass also decreases. No evidence suggests that energy restriction decreases the number of adipocytes, which are believed to remain constant after growth periods. Exercise may reduce new adipocyte formation, especially in animal models, but it does not decrease the total number of established adipocytes.