SEM image of adipose tissue created by David Gregory and Debbie Marshall, and courtesy of Wellcome Images (Creative Commons by-nc-nd 2.0 UK: England & Wales).
Excess triglycerides (TGs) are either stored in adipose tissue or burned to meet the body’s energy demands through a process known as lipolysis. Although it has been proposed that the balance between TG storage and lipolysis is dysregulated in obesity, studies that quantify and compare lipid turnover in obese versus non-obese humans were lacking. In a new report, Arner et al. used carbon dating to calculate the age of TGs in adipocytes, by taking advantage of atmospheric 14C released during above-ground nuclear testing that took place between 1955 and 1963. Their results indicate that adipocytes in healthy individuals live for an average of 9.5 years, during which their TG content is replaced six times. In obese individuals, lipid turnover was lower and the rate of storage increased, causing accumulation of adipose tissue. By contrast, patients with familial combined hyperlipidaemia had low rates of both lipid storage and turnover, an imbalance that probably contributes to the increased circulating levels of TGs that are characteristic of this disease. Targeting the mechanisms of TG turnover might therefore be a promising therapeutic strategy to combat metabolic diseases.
Arner P., Bernard S., Salehpour M., Possnert G., Liebl J., Steier P., Buchholz B. A., Eriksson M., Arner E., Hauner H., et al. ( 2011). Dynamics of human adipose lipid turnover in health and metabolic disease. Nature [Epub ahead of print] 10.1038/nature10426