Effect of estrogen on post-heparin lipolytic activity. Selective decline in hepatic triglyceride lipase.

Abstract

A B S T R A C T The rise in plasma triglyceride (TG) levels associated with estrogen administration has been thought to arise from impaired clearance because of the uniform suppression of post-heparin lipolytic activity (PHLA). Recently PHLA has been shown to consist of two activities: hepatic TG lipase and extrahepatic lipoprotein lipase (LPL). To determine whether estrogen might induce a selective decline in one of these activities, both hepatic TG lipase and extrahepatic LPL were measured in postheparin plasma from 13 normal women before and after 2 wk of treatment with ethinyl estradiol (1 ,ug/kg per day). Hepatic TG lipase and extrahepatic LPL were determined by two techniques: (a) separation by heparin-Sepharose column chromatography, and (b) selective inhibition with specific antibodies to post-heparin hepatic TG lipase and milk LPL. Estrogen uniformly depressed hepatic TG lipase as measured by affinity column (-68±12%, mean±SD, P < 0.001) or antibody inhibition (-63±11%, P < 0.001). Extrahepatic LPL was not significantly changed by affinity column (-22±40%) or antibody inhibition (-3+42%). Direct measurement of adipose tissue LPL from buttock fat biopsies also showed no systematic change in the activated form of LPL measured as heparin-elutable LPL (+64+164%) or in the tissue form of LPL measured in extracts of acetone-ether powders (+21±77%). The change in hepatic TG lipase correlated with the change in PHLA (r = 0.969, P < 0.01). However, neither the change in PHLA nor hepatic TG lipase correlated with the in-

Optimizing cardiovascular risk reduction during antihypertensive therapy.

“…31 Part of the explanation for differences between obese men and women in the responses of lipids to weight loss may result from gender differences in fat distribution. 32 Estrogens increase HDL levels 33 and androgens reduce them. 34 - 35 These sex hormone-related changes in lipids may account for the relative protection against coronary artery disease seen in premenopausal women and the reversal of this protection along with increases in LDL and decreases in HDL observed after menopause.…”

Association of decreased sex hormone binding globulin and cardiovascular risk factors.

“…51 Hepatic triglyceride lipase is also increased by anabolic steroids, 351 is lower in women than in men, 5152 and is decreased by ethinyl estradiol. 53 Since both Evans et al 6 and our group 17 have shown that premenopausal women with upper body adiposity have increased percent free testosterone and decreased sex hormone binding globulin, it is possible that the effect of body fat distribution on HDL cholesterol may be mediated through alterations in hepatic triglyceride lipase. However, no study thus far has directly examined the effect of body fat distribution on hepatic triglyceride lipase.…”

Lipid Metabolism in Endotoxic Rats

“…After insulin injection into rats, marked increases in the activity of LPL were observed but that of H-TGL was not affected (7). Estrogen administration was found to suppress only H-TGL activity (2). Similarly, thyroxine has also been shown to have a selective effect on H-TGL (10).…”