THYROID-HORMONE RAPIDLY INCREASES CHOLESTEROL 7-ALPHA-HYDROXYLASE MESSENGER-RNA LEVELS IN HYPOPHYSECTOMIZED RATS

被引:38
作者
NESS, GC [1 ]
PENDLETON, LC [1 ]
ZHAO, ZH [1 ]
机构
[1] UNIV S FLORIDA,INST BIOMOLEC SCI,TAMPA,FL 33612
来源
BIOCHIMICA ET BIOPHYSICA ACTA-LIPIDS AND LIPID METABOLISM | 1994年 / 1214卷 / 03期
关键词
THYROID HORMONE; CHOLESTEROL; 7-ALPHA-HYDROXYLASE; (RAT);
D O I
10.1016/0005-2760(94)90068-X
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The induction of hepatic cholesterol 7 alpha-hydroxylase mRNA by triiodothyronine was investigated in hypophysectomized rats. These rats exhibited markedly decreased levels of cholesterol 7 alpha-hydroxylase mRNA compared to normal controls. An increase in this mRNA could be detected within 30 min after giving triiodothyronine. A triiodothyronine dose of 0.25 mu g per 100 g of body weight, which produces 50% occupancy of hepatic nuclear thyroid hormone receptors, caused significant increases in hydroxylase mRNA levels. The half-life of cholesterol 7 alpha-hydroxylase mRNA was about 30 min and was not affected by thyroid hormone. Administration of the protein synthesis inhibitor, cycloheximide, after triiodothyronine caused superinduction. Hepatic HMG-CoA reductase mRNA levels, which are also low in livers from hypophysectomized rats, were unaffected by these doses of hormone within the 2 h time-frame examined in these studies. The results suggest that thyroid hormone may exert a primary affect on the expression of the hepatic cholesterol 7 alpha-hydroxylase gene. This could explain, in part, the hypocholesterolemic effect of thyroid hormone.
引用
收藏
页码:229 / 233
页数:5
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