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Lipoprotein metabolism in the ovariectomized rat
Journal of Lipid Research
|November 1, 1983
Summary
Ovariectomy in rats increases plasma lipids by altering low-density lipoproteins (LDL) and high-density lipoproteins (HDL). This study reveals increased LDL production and catabolism contribute to higher LDL levels post-ovariectomy.
Area of Science:
- Endocrinology
- Lipid Metabolism
- Cardiovascular Research
Background:
- Ovariectomy in rats leads to hyperlipoproteinemia, characterized by elevated cholesterol, triglycerides, and apolipoproteins B, E, and C.
- Previous studies linked these changes to hormonal imbalances following ovariectomy.
Purpose of the Study:
- To investigate the specific roles of low-density lipoproteins (LDL) and high-density lipoproteins (HDL) in post-ovariectomy hyperlipoproteinemia.
- To elucidate the mechanisms underlying increased plasma LDL concentrations in ovariectomized rats.
Main Methods:
- Analysis of plasma lipids and apolipoproteins in ovariectomized and control rats.
- Agarose chromatography to assess LDL and HDL particle size.
- Calculation of apolipoprotein B pool sizes and turnover rates to determine LDL metabolism.
Main Results:
- Increased LDL and HDL concentrations were primarily responsible for lipid changes after ovariectomy.
- LDL and HDL particle sizes differed between groups; apolipoprotein B associated with smaller particles and apolipoprotein E with larger particles in ovariectomized rats.
- Apolipoprotein B turnover rate increased nearly twofold, indicating enhanced LDL synthesis and catabolism.
Conclusions:
- Post-ovariectomy hyperlipoproteinemia is significantly driven by alterations in LDL and HDL.
- Increased plasma LDL levels in ovariectomized rats result from an initial rise in production followed by enhanced catabolism, establishing a new steady state.