Development, food intake, and ethinylestradiol influence hepatic triglyceride lipase and LDL-receptor mRNA levels in rats.
The influence of development and ethinylestradiol on low density lipoprotein (LDL)-receptor mRNA and hepatic triglyceride lipase (HTGL) activity and mRNA levels was studied in rat liver and intestine. Intestinal LDL-receptor mRNA levels are maximal in the perinatal period, whereas liver LDL-receptor and HTGL mRNA levels are highest after weaning in adult life. All mRNA levels reach a maximum between day 15 and 20 when rats still consume a lipid-rich diet, and increase twofold during weaning. Liver and intestinal LDL-receptor mRNA levels are not influenced by ovariectomy, but increase after ethinylestradiol treatment. Liver LDL-receptor mRNA shows a dose-dependent increase after ethinylestradiol and a sevenfold rise in liver LDL-receptor mRNA is attained with a dose of 2000 micrograms/day. Intestinal LDL-receptor mRNA increases slightly more than twofold after ethinylestradiol and this increase is not dose-dependent. Changes in LDL-receptor mRNA are independent of changes in food intake induced by ethinylestradiol treatment, since they are still observed after pair-feeding. The ethinylestradiol-induced increases in LDL-receptor mRNA levels are reflected by decreased serum apoB levels. HTGL mRNA levels increase after ovariectomy and show a dose-dependent decrease after ethinylestradiol. Pair-feeding abolishes the increase seen after ovariectomy, while the estrogen-mediated decrease is attenuated. These alterations in HTGL mRNA are reflected by similar changes in liver HTGL activity.(ABSTRACT TRUNCATED AT 250 WORDS)
Laboratorium voor Experimentele Geneeskunde en Endocrinologie, Katholieke Universiteit Leuven, Belgium.
B
B
Staels
H
H
Jansen
A
A
van Tol
G
G
Stahnke
H
H
Will
G
G
Verhoeven
J
J
Auwerx
D000818:Animals; D004435:Eating; D004997:Ethinyl Estradiol / Q000494:pharmacology*; D005260:Female; D005786:Gene Expression Regulation; D007413:Intestinal Mucosa / Q000378:metabolism; D007422:Intestines / Q000201:enzymology; D008049:Lipase / Q000378:metabolism*; D008099:Liver / Q000201:enzymology* / Q000254:growth & development; D008297:Male; D010052:Ovariectomy; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D011973:Receptors, LDL / Q000235:genetics* / Q000378:metabolism; D012737:Sex Factors
D012333:RNA, Messenger; D011973:Receptors, LDL; D004997:Ethinyl Estradiol; D008049:Lipase