Studies on the activity of acyl-coA:Cholesterol o-acyltransferase and acid cholesterol ester synthetase in rat aortas

A method involving the use of isolated cholesterol ester-storage granules as substrate is described for the assay of cholesterol esterase in rabbit ovarian tissues. Activities of cholesterol esterase 100–200-fold higher than those previously reported in ovarian tissues were measured by using this method. In addition to that of cholesterol esterase, activities of cholesterol ester synthetase, cholesterol side-chain cleavage enzyme and 3β-hydroxy steroid dehydrogenase were determined in rabbit ovarian interstitial tissue and corpora lutea. Activities of these enzymes are in general compatible with the flows through them measured under a variety of conditions both in vivo and in vitro. It is concluded that, in the rabbit ovarian tissues investigated, these enzymes are capable of catalysing the conversions usually attributed to them.

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Cholesterol Ester Synthetase and Neutral Hydrolase Activities of Aortic Wall in Diabetic Rat

The Journal of Japan Atherosclerosis Society ◽

10.5551/jat1973.14.6_1283 ◽

1987 ◽

Vol 14 (6) ◽

pp. 1283-1286

Author(s):

Tomio ONUMA ◽

Masahiro TSUTSUI ◽

Sigeru OCHIAI ◽

Akitoshi BOKU ◽

Atsuko YANADA ◽

...

Keyword(s):

Cholesterol Ester ◽

Aortic Wall ◽

Diabetic Rat ◽

Ester Synthetase

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Control of ovarian cholesterol ester biosynthesis

Biochemical Journal ◽

10.1042/bj1320313 ◽

1973 ◽

Vol 132 (2) ◽

pp. 313-321 ◽

Cited By ~ 32

Author(s):

A. P. F. Flint ◽

D. L. Grinwich ◽

D. T. Armstrong

Keyword(s):

Luteinizing Hormone ◽

Cyclic Amp ◽

Cholesterol Ester ◽

Cholesterol Esterase ◽

Interstitial Tissue ◽

Steroid Synthesis ◽

Precursor Pool ◽

Ester Synthetase

1. Experimental evidence is presented for a role of progesterone and 20α-hydroxypregn-4-en-3-one as inhibitors of cholesterol ester synthetase in the acute depletion of ovarian cholesterol ester after trophic stimulation. 2. Luteinizing hormone in vitro decreased by 84% the rate of esterification of cholesterol with added [14C]oleate by slices of rabbit ovarian interstitial tissue; this effect was mimicked by cyclic AMP (adenosine 3′:5′-cyclic monophosphate) in vitro, and occurred without large changes in precursor pool sizes or membrane permeability. 3. Cyclic AMP was shown to have no direct effect on cholesterol ester synthetase or cholesterol esterase in cell-free extracts of rabbit ovarian interstitial tissue, but decreased the activity of cholesterol ester synthetase (not that of cholesterol esterase) in extracts prepared from slices previously incubated with it. 4. The inhibitory effect of cyclic AMP on esterification of cholesterol with added [14C]-oleate was prevented by both cycloheximide and aminoglutethimide phosphate (which also inhibited steroid synthesis in response to cyclic AMP). 5. Cyclic AMP raised the intracellular concentrations of progesterone and 20α-hydroxypregn-4-en-3-one in incubated slices by factors of 2.8 and 3.9 respectively. 6. Cycloheximide and aminoglutethimide phosphate administered in vivo blocked cholesterol ester depletion in response to luteinizing hormone in rats; in these ovaries cycloheximide and aminoglutethimide phosphate decreased the concentrations of progesterone and 20α-hydroxypregn-4-en-3-one and luteinizing hormone raised them. 7. Progesterone and 20α-hydroxypregn-4-en-3-one added to cell-free extracts of rabbit ovarian interstitial tissue in vitro (at concentrations comparable with those found in incubated slices) inhibited cholesterol ester synthetase by up to 85%. 8. The results are discussed with reference to the acute control of cholesterol ester concentrations in the ovary and adrenal cortex.

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