Journal of Lipid Research, Vol 18, 24-31, Copyright © 1977 by Lipid Research, Inc.
Induction of HMG CoA reductase by the administration of 20,25- diazacholesterol
R Langdon, S El-Masry and RE Counsell
This paper describes the direct examination of HMG CoA reductase activity
in rats treated with 20,25-diazacholesterol. Conversion of acetyl CoA and
HMG CoA to mevalonate increased to over 200% of control values in the
microsomes and in the 12,000 g supernatant of liver homogenates after 5
days of treatment. The time course of induction coincided with the
development of hypocholesterolemia. Animal weights, liver weights, and
microsomal protein content did not vary significantly between animal
groups. Incubations to which the compound was introduced in vitro in
concentrations as great as 0.5 mM produced no significant difference from
control incubations. Similar treatment of the animals with
7-ketocholesterol, a cholesterol derivative reported to repress HMG CoA
reductase activity in tissue cultures, produced no appreciable difference
in reductase activity or serum steroid levels in vivo.