Origin of estradiol fatty acid esters in human ovarian follicular fluid.
The estradiol fatty acid esters are the most potent of the naturally occurring steroidal estrogens. These esters are present predominantly in fat, where they are sequestered until they are hydrolyzed by esterases. Thus they act as a preformed reservoir of estradiol. We have previously shown that ovarian follicular fluid from patients undergoing gonadotropin stimulation contains very high amounts of estradiol fatty acid esters (approximately 10(-7) M). The source of these esters is unknown. They can be formed by esterification of estradiol in the follicular fluid by lecithin:cholesterol acyltransferase (LCAT), or in the ovary by an acyl coenzyme A:acyltransferase. In order to determine which of these enzymatic processes is the source of the estradiol esters in the follicular fluid, we incubated [3H]estradiol with follicular fluid and cells isolated from human ovarian follicular fluid and characterized the fatty acid composition of the [3H]estradiol esters biosynthesized in each. In addition, we characterized the endogenous estradiol fatty acid esters in the follicular fluid and compared them to the biosynthetic esters. The fatty acid composition of the endogenous esters was different than those synthesized by the cellular acyl coenzyme A:acyltransferase, and the same as the esters synthesized by LCAT, demonstrating that the esters are produced in situ in the follicular fluid. Although the role of these estradiol esters in the ovary is not known, given their remarkable estrogenic potency it is highly probable that they have an important physiological role.
Pahuja
S L
SL
Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, Connecticut 06510, USA.
Kim
A H
AH
Lee
G
G
Hochberg
R B
RB
D002855:Chromatography, Thin Layer; D004228:Dithionitrobenzoic Acid / Q000494:pharmacology; D004958:Estradiol / Q000096:biosynthesis / Q000378:metabolism*; D005227:Fatty Acids / Q000096:biosynthesis / Q000378:metabolism*; D005260:Female; D015571:Follicular Fluid / Q000378:metabolism*; D006107:Granulosa Cells / Q000378:metabolism; D006801:Humans; D010053:Ovary / Q000378:metabolism*; D007862:Phosphatidylcholine-Sterol O-Acyltransferase / Q000037:antagonists & inhibitors; D011247:Pregnancy
D005227:Fatty Acids; D004958:Estradiol; D004228:Dithionitrobenzoic Acid; D007862:Phosphatidylcholine-Sterol O-Acyltransferase