title: Effect of long-term administration of estrogens on the subcellular distribution of cholesterol and the activity of rate-limiting enzymes of cholesterol biosynthesis and degradation in pigeon liver.
abstract: To determine the mechanism of the hypocholesteremic effect of estrogens noted in pigeon, studies were done on the subcellular distribution of cholesterol and the activity of beta-hydroxy-beta-methylglutaryl CoA reductase (HMG-CoA reductase) and and cholesterol 7alpha-hydroxylase in pigeon liver after long-term (6 months) estrogen administration. Estrogens significantly reduced free cholesterol concentration in microsomes and mitochondrial fraction. The concentration of cholesteryl ester was reduced in the supernatant fraction. The activity of HMG-CoA reductase was significantly reduced in the estrogen-treated birds, while cholesterol 7alpha-hydroxylase activity showed no changes. Thus, the hypocholesteremic effect of estrogen noted in pigeons could be mainly due to the inhibition of cholesterol biosynthesis in the liver.
mesh_terms: D000818:Animals; D002784:Cholesterol / Q000096:biosynthesis*; D002790:Cholesterol 7-alpha-Hydroxylase / Q000378:metabolism; D002788:Cholesterol Esters / Q000032:analysis; D010856:Columbidae / Q000378:metabolism*; D004967:Estrogens / Q000494:pharmacology*; D006903:Hydroxymethylglutaryl CoA Reductases / Q000378:metabolism; D008099:Liver / Q000378:metabolism*; D008862:Microsomes, Liver / Q000378:metabolism; D008930:Mitochondria, Liver / Q000378:metabolism
chemical_list: D002788:Cholesterol Esters; D004967:Estrogens; D002784:Cholesterol; D006903:Hydroxymethylglutaryl CoA Reductases; D002790:Cholesterol 7-alpha-Hydroxylase