PC27 EFFECT OF OIL-SUPPLEMENTED DIETS ON LIVER EXPRESSION OF PPAR ALPHA-RELATED GENES IN PREGNANT RATS

Abstract

Introduction: During late pregnancy, hypertriglyceridemia is developed. Although maternal triglyceridemia has been correlated to newborns weight, we have previously found that a hypotriglyceridemic drug like fenofibrate, was unable to reduce triglyceridemia in late pregnant rats but impaired fetal growth (1). These fibrates modulate the hepatic expression of genes related to lipid metabolism through the activation of the peroxisome proliferator-activated receptor alpha (PPARalpha). Since fatty acids have also been demonstrated to activate PPARalpha, we studied the effects of diets with different fatty acids compositions in pregnant rats on maternal triglyceridemia and the expression of PPAR related genes. Methods: Pregnant rats were fed a semi-synthetic diet containing 10% of either palm-, sunflower-, olive- or fish-oil throughout pregnancy. All the animals were killed on day 20. Pregnant rats that were fed standard pellet were also studied in parallel. Liver and blood were collected for later determinations following previously described methodology (2). Results: The expression of carnitine palmitoyltransferase (CPT-I), a PPARalpha target gene, was higher in those rats fed the different oil-supplemented diets as compared to those on pellets. These changes for CPT-I expression were related to those of plasma insulin and FFA levels. Rats fed either sunflower-or fish-oil diets showed higher apolipoprotein B expression than those fed palm- or olive-oil diets. Regarding genes related to lipogenesis, sterol regulatory element binding protein (SREBP1c) expression was higher in those rats fed any of the oil-supplemented diets except for the olive oil as compared to those fed pellets. On the contrary, the expression of fatty acid synthase (FAS) expression was lower in all the rats fed the oil-supplemented diets than those on pellets. The expression of stearoyl-CoA desaturase (SCD-1) was lower in rats fed sunflower- and fish-oil diets than in those fed either palm- or olive-oil. Similarly to the effect previously seen with fenofibrate in pregnant rats (1), the expression of the acute-phase protein, alpha2-macroglobulin, was reduced by all the oil-supplemented diets. These inter-group differences appeared similar to those found for maternal triglyceridemia. Conclusion: Changes in gene expression caused by the oil-supplemented diets indicate an enhanced fatty acid catabolism and decreased lipogenesis and acute-phase response, which would explain the significant reduction on triglyceridemia produced by the oil diets in pregnant rats.