Effects of dietary coconut oil on apolipoprotein B synthesis and VLDL secretion by calf liver slices.
Incorporation of coconut oil (CO) rich in lauric acid into the milk diet induces a lipid infiltration of the liver (steatosis) in 1-month-old calves. Among possible steps involved in diet-induced liver steatosis, the ability of the calf liver to synthesize apolipoprotein (Apo) B and to secrete it as part of VLDL particles was investigated. Liver samples were taken from calves fed for 17 d on a conventional milk replacer containing CO (n 5) and beef tallow (BT, n 4) as reference. Samples were cut into slices 0.5 mm thick and subsequently incubated for 12 h in a medium containing a [(35)S]methionine-[(35)S]cysteine mix and 0.8 mm-sodium laurate or oleate, the major fatty acids of CO and BT diets respectively. Concentrations of total [(35)S]proteins, [(35)S]albumin and [(35)S]ApoB in liver cells were 2-fold lower 0.0004 and 0.03 respectively) in CO- than in BT-fed calves. Although the total amount of proteins secreted (including albumin) was similar in both groups of calves, the amount of VLDL-[(35)S]Apo secreted was 2-fold lower (P = 0.004) in CO- than in BT-fed calves. These results suggest that a CO-enriched milk diet induces in preruminant calves a lipid infiltration of the liver by decreasing ApoB synthesis, leading to a reduction in secretion of VLDL particles.
Gruffat-Mouty
D
D
Unité de Recherches sur les Herbivores, Equipe Nutriments et Métabolismes, Institut National de Recherche Agronomique, Centre de Recherches Clermont Ferrand - Theix, 63122 Saint Genès Champanelle, France. gruffat@clermont.inra.fr
Graulet
B
B
Durand
D
D
Samson-Bouma
M E
ME
Bauchart
D
D
D000818:Animals; D001055:Apolipoproteins B / Q000096:biosynthesis*; D001682:Biological Availability; D002417:Cattle; D002418:Cattle Diseases / Q000139:chemically induced / Q000378:metabolism*; D000074263:Coconut Oil; D046508:Culture Techniques; D004041:Dietary Fats / Q000008:administration & dosage; D005234:Fatty Liver / Q000662:veterinary; D008079:Lipoproteins, VLDL / Q000378:metabolism*; D008099:Liver / Q000378:metabolism*; D008297:Male; D010938:Plant Oils / Q000008:administration & dosage
D001055:Apolipoproteins B; D004041:Dietary Fats; D008079:Lipoproteins, VLDL; D010938:Plant Oils; D000074263:Coconut Oil