title: Vitamin E prevents the platelet abnormalities induced by estrogen in rat.
abstract: Platelet lipid biosynthesis in relation to aggregation has been studied in female rats treated with ethynylestradiol and fed laboratory chow or a vitamin E-deficient diet. In both normal and vitamin E-deficient rats, administration of ethynylestradiol highly significantly (p less than .001) increased the biosynthesis of total lipids but mostly of lanosterol (+ dihydrolanosterol) by thirteen-fold in normal rats and by nine-fold in vitamin E-deficient rats. The increased lipid synthesis was associated with a higher response of platelets to thrombin-induced aggregation. Concomitant administration of alpha-tocopherol acetate in both normal and vitamin E-deficient rats depressed markedly the enhanced lipid synthesis and aggregation induced by estrogen. Administration of ethynylestradiol lowered considerably the level of vitamin E in plasma but not in platelets. Treatment by tocopherol partly corrected the low plasma level of vitamin E resulting from estrogen administration. In vitro addition of lanosterol to platelets highly significantly increased the response of platelets to thrombin- and ADP-induced aggregation. This hyperaggregability was almost entirely inhibited by preincubation of platelets with tocopherol acetate. In the present in vivo and in vitro studies, alpha-tocopherol was able to neutralize most of the adverse effects of estrogen on blood platelets.
mesh_terms: D000818:Animals; D001792:Blood Platelets / Q000187:drug effects* / Q000378:metabolism; D004997:Ethinyl Estradiol / Q000037:antagonists & inhibitors*; D005260:Female; D066298:In Vitro Techniques; D007810:Lanosterol / Q000097:blood / Q000494:pharmacology; D008055:Lipids / Q000097:blood; D010974:Platelet Aggregation / Q000187:drug effects; D051381:Rats; D014810:Vitamin E / Q000494:pharmacology*; D014811:Vitamin E Deficiency / Q000097:blood
chemical_list: D008055:Lipids; D014810:Vitamin E; D007810:Lanosterol; D004997:Ethinyl Estradiol