Regulation of neutral cholesterol esterase and acyl-CoA : cholesterol acyltransferase in the rat adrenal gland

Publisher Website
Google Scholar
Abstract
The activities of neutral cholesterol esterase and acyl-CoA:cholesterol acyltransferase in rat adrenal gland were measured at various time intervals over 24 h. The activity of cholesterol esterase displayed diurnal rhythm, with a major peak at the onset of darkness coinciding with the peak in the diurnal rhythm of plasma corticosterone concentration. The activity of acyl-CoA:cholesterol acyltransferase also exhibited a characteristic diurnal rhythm, with the minimum activity occurring 3 h after the onset of darkness. The profile of the rhythm exhibited by the activity of the esterifying enzyme was similar to the mirror image of the pattern of diurnal rhythm in the activity of 3-hydroxy-3-methylglutary-CoA reductase. Microsomal non-esterified cholesterol showed a gradual decline with a significant decrease in concentration at the onset of darkness, thus suggesting that diurnal removal of cholesterol in the environment of the esterifying enzyme and hydroxymethylglutaryl-CoA reductase leads to such diurnal decrease or increase in the activities of these 2 enzymes. Acute administration of ACTH led to a 3-fold increase in the activity of cholesterol esterase, a 50% decrease in the activity of acyl-CoA:cholesterol acyltransferase and a 2-fold increase in the activity of hydroxymethylglutaryl-CoA reductase. ACTH administration also resulted in a significant decrease in microsomal non-esterified cholesterol and an increase in plasma corticosterone concentration. ACTH evidently plays an important part in generating the diurnal rhythm in the activities of the 3 enzymes.

This publication has 13 references indexed in Scilit: