EFFECT OF THYROID STATE ON ENZYMES LINKED WITH LIPOPROTEIN METABOLISM IN RATS

Publisher Summary This chapter discusses an experiment to study the effect of thyroid state on enzymes linked with lipoprotein metabolism in rats. Specific pathogen-free female Wistar rats (200–250 g) bred and kept under standard laboratory conditions were used. The rats were divided into the following experimental groups: (1) absolute controls (AC), vehiculum-treated control rats (VC): for 20 days 0.25 ml medium per 100 g body weight were injected daily subcutaneously; (2) rats surgically thyreoidectomized (TCET) 20 days before experiment; and (3) T 4 rats: for 20 days thyroxine was injected daily subcutaneously. The rats were used for experiments after 16 h of starvation. The lipoprotein lipase (LPL) activity was determined in the adipose tissue, heart, and diaphragm and the serum lecithin:cholesterol acyltransferase (LCAT) activity was determined. For the determination of the plasma post-heparin lipolytic activity (PHLA), the rats were narcotized with ether. 25 IU of heparin per 100 g body weight were injected to the vena jugularis . Blood was collected exactly 10 and 60 min later and the plasma was used for the determination of PHLA. It was found that after TECT, cholesterol was significantly decreased in the very low density lipoproteins fraction and increased in the low density lipoproteins fraction. The plasma cholesterol level was significantly increased.