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)
Staels
B
B
Laboratorium voor Experimentele Geneeskunde en Endocrinologie, Katholieke Universiteit Leuven, Belgium.
Jansen
H
H
van Tol
A
A
Stahnke
G
G
Will
H
H
Verhoeven
G
G
Auwerx
J
J
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