[Cholesterol esterification in the serum of hypothyroid rats]

The ratio of unesterified to total serum cholesterol in hypothyreotic rats has been studied. Extreme rat hypothyreosis of identical degree was induced by radiothyroidectomy (group R-HT) and feeding of thyreostatics (groups MTU-HT and MMI-HT). Determination of total serum cholesterol content and the unesterified cholesterol content resulted in following changes (all changes significant for p < 0,001): 1. Higher total cholesterol in hypothyreotic rats 4 and 7 weeks after beginning the experiments as compared to the controls. 2. The ratio of unesterified cholesterol to total cholesterol was increased in all hypothyreotic groups. It is discussed, that the esterification reaction in serum catalyzed by the lecithin-cholesterol-acyltransferase (LCAT) is diminished in the hypothyreotic state.