AIM: Peroxisome proliferator-activated receptor (PPAR) α is a nuclear receptor that through sensing fatty acid metabolites as ligands regulates genes involved in lipid transport and metabolism (Atherosclerosis 205: 413, 2009). Disruption of the PPARα gene, however, may not lead to apparent changes in phenotypes, perhaps due to compensation by other members of the nuclear receptor superfamily. We characterized cholesterol homeostasis in PPARα-null mice on a C57BL/6 background with a focus on HDL metabolism. METHODS AND RESULTS: PPARα-null mice gained weight significantly more than wild-type mice, with more prominence in females, without changing the HDL-apoprotein clearance rate. Clearance of plasma HDL-cholesteryl ester was retarded, more prominently in females. Uptake of HDL-cholesteryl ester by the adrenal glands and ovaries was found to be decreased in female mutant mice. The ATP binding cassette transporter A1 (ABCA1), liver X receptor α and PPARδ mRNAs were decreased in the liver, and that encoding scavenger receptor B1 (SR-B1) decreased in the adrenal glands of these mice. Although the plasma lipoprotein profile did not show major differences, some subtle changes were found in the mutants, including HDL properties being consistent with its slow turnover. Cholesterol content in the organs was not significantly influenced except for a paradoxical increase in gonad glands. CONCLUSIONS: We conclude that the plasma HDL turnover rate is retarded in PPARα-null mice, perhaps more prominently in females.
AIM: Peroxisome proliferator-activated receptor (PPAR) α is a nuclear receptor that through sensing fatty acid metabolites as ligands regulates genes involved in lipid transport and metabolism (Atherosclerosis 205: 413, 2009). Disruption of the PPARα gene, however, may not lead to apparent changes in phenotypes, perhaps due to compensation by other members of the nuclear receptor superfamily. We characterized cholesterol homeostasis in PPARα-null mice on a C57BL/6 background with a focus on HDL metabolism. METHODS AND RESULTS: PPARα-null mice gained weight significantly more than wild-type mice, with more prominence in females, without changing the HDL-apoprotein clearance rate. Clearance of plasma HDL-cholesteryl ester was retarded, more prominently in females. Uptake of HDL-cholesteryl ester by the adrenal glands and ovaries was found to be decreased in female mutant mice. The ATP binding cassette transporter A1 (ABCA1), liver X receptor α and PPARδ mRNAs were decreased in the liver, and that encoding scavenger receptor B1 (SR-B1) decreased in the adrenal glands of these mice. Although the plasma lipoprotein profile did not show major differences, some subtle changes were found in the mutants, including HDL properties being consistent with its slow turnover. Cholesterol content in the organs was not significantly influenced except for a paradoxical increase in gonad glands. CONCLUSIONS: We conclude that the plasma HDL turnover rate is retarded in PPARα-null mice, perhaps more prominently in females.