Cortisol, acth, and biosynthesis of apolipoproteins in rat hepatocytes

Abstract

The effect of cortisol (5 mg/kg, 5 and 10 days) on biosynthesis of apoproteins of very low density lipoproteins in the liver and on synthesis of apoproteins of very low, low, and high density lipoproteins in blood serum of intact animals was investigatedin vivo. Cortisol, within the periods specified, inhibits biosynthesis of apoproteins of very low density lipoproteins (apo-VLDL) in liver. After adrenalectomy apo-VLDL synthesis is intensified and this effect is abolished during replacement administration, of cortisol. Apoprotein synthesis is activated 5 h after a single injection of cortisol and ACTH; a single dose and prolonged administration of cortisol give opposite results. Investigation of the specific radioactivity of apolipoproteins in the blood serum indicates a change in lipoprotein metabolism: disturbance of conversion of very low density into low density lipoproteins. An important role in the pathogenesis of the hyperlipidemia induced by cortisol within the specified period is played not by increased lipoprotein synthesis in the liver, but by a disturbance of their metabolism in the blood.