Abstract
Abstract
The content of free and esterified cholesterol in epididymal and subcutaneous adipocytes was measured during starvation in adult male rats in order to test the hypothesis that adipose tissue cholesterol esters are mobilized concomitantly with free cholesterol and triglyceride during starvation. Plasma and liver lipid concentrations were also determined as a function of time during food deprivation. Plasma triglyceride decreased significantly within 72 hr and liver triglyceride increased significantly after 144 hr of starvation. Plasma total cholesterol also decreased due to starvation, but only after 144 hr. No significant alteration in hepatic cholesterol was observed at any time. In epididymal adipose cells, free cholesterol was mobilized during fasting while the cholesterol ester pool remained constant. In marked contrast, cells from the subcutaneous depot showed no consistent changes in either free or esterified cholesterol despite the fact that cells lost about 55% of their triglyceride pool. These data provide another example of the metabolic heterogeneity of the various adipose tissue beds. Although neither cholesterol ester turnover nor hydrolase activity was directly measured, the results appear to be inconsistent with the hypothesis that an adipose tissue cholesterol ester hydrolase plays a role in the hydrolysis of stored esters during acute starvation, and further suggest that the turnover of cholesterol and cholesterol esters is probably different in adipose tissue.
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