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Lipoproteins and apoproteins of fetal and newborn piglets
Insights
Newborn pigs show rapid serum lipid changes post-feeding, with high-density lipoproteins (HDL) peaking early. Their lipoprotein profile evolution mirrors human infants, validating pigs as a model for perinatal nutrition studies.
Area of Science:
- Lipid metabolism and lipoprotein analysis in neonatal physiology.
Background:
- Serum lipid levels are minimal in fetuses and newborns, increasing significantly after initial feeding.
- Cholesterol exists predominantly in free form initially, with esterified cholesterol rising post-feeding.
Purpose of the Study:
- To characterize the dynamic changes in serum lipids and lipoproteins in young pigs after birth.
- To compare the lipoprotein profile evolution in neonatal pigs with that of human infants.
- To validate the young pig as a model for perinatal nutrition research.
Main Methods:
- Analysis of serum lipid concentrations, including cholesterol and phospholipids.
- Characterization of lipoprotein composition and density.
- Identification of apoproteins in different lipoprotein fractions.
Main Results:
- Rapid increase in serum lipids post-feeding, with phospholipids indicating roles beyond triglyceride synthesis.
- Fetal and neonatal lipoproteins share similarities with adults, but HDL are denser and protein-rich.
- Neonatal pigs exhibit a high capacity for synthesizing HDL and apoprotein AI, exceeding adult and juvenile pig levels.
Conclusions:
- The early lipoprotein metabolism in pigs closely resembles that of human neonates.
- The young pig serves as a valuable animal model for investigating perinatal nutrition and its impact on lipid metabolism.
Abstract:
Serum lipids, very low in the fetus and at birth, increased rapidly after the first feeding. Cholesterol was mainly in the free form. Esterified cholesterol rose rapidly, but free cholesterol remained in high proportions (30%) until after weaning. Very high phospholipid concentrations show that triglycerides are not the only major product of esterification and suggest a possible use for energetic purposes. Fetal lipoproteins had a general pattern similar to that of adults, but high-density lipoproteins (HDL) were denser (1.128 g/ml) and correspondingly richer in proteins. The presence of apoprotein AI and of the light intestinal form of apoprotein B in the triglyceride-rich fractions as well as that of apoprotein AIV in HDL was indicative of an early contribution of enterocytes to the lipoprotein pool. Low-density lipoprotein apoproteins were heterogeneous until 14 days, as they are in the human fetus, and contained, besides apoprotein B, all the main apoproteins, HDL reached concentrations of 400 mg/100 ml at 3 and 4 weeks of age, above 3-fold higher than those of chow-fed adults, but also 1.5-fold higher than those of growing pigs fed a 20% fat diet, thereby showing a high capacity of the very young animal to synthesize HDL and apoprotein AI in particular. The many similarities with the evolution of lipoprotein in the newborn human validate the young pig as a model in the study of perinatal nutrition.