Effect of levothyroxine on the fibrinolytic system, lipid profile and plasma glucose in rats

摘要

Thyroid hormones exert many effects on the cardiovascular system. Thyroid abnormality enhances atherosclerosis not only through general risk factors (dyslipidemia) but also via a close relationship with hemodynamic parameters; levothyroxine sodium modulates some elements of the fibrinolytic system, though the relationship is not completely clear. The aim of the current study was to investigate the effects of levothyroxine sodium on fibrinolytic parameters such as plasminogen activator (PA) in rat heart, plasma levels of PA and plasminogen activator inhibitor (PAI), plasma glucose, and the serum lipid profile. Rats were given 50 microgram 100 g-1 body weight levothyroxine sodium for one week. Rat heart PA activity was significantly greater in the treated animals than in controls. There were no significant differences between the two groups of rats in PA, PAI or plasma glucose. Total cholesterol and LDL-cholesterol levels were lower in sera from the treated group, resulting in decreased LDL/HDL and total cholesterol/HDL-cholesterol ratios. These results suggest that levothyroxine sodium treatment could have clinical value: it raised PA activity in the heart and reduced the blood cholesterol level. It could therefore confer a beneficial effect on cardiovascular disease risk.