Consumption of casein instead of soybean protein produces a transient risein the concentration of sphingomyelin in VLDL in rats

Citation
Mjh. Geelen et al., Consumption of casein instead of soybean protein produces a transient risein the concentration of sphingomyelin in VLDL in rats, J NUTR, 129(12), 1999, pp. 2119-2122
Citations number
16
Categorie Soggetti
Food Science/Nutrition","Endocrinology, Nutrition & Metabolism
Journal title
JOURNAL OF NUTRITION
ISSN journal
00223166 → ACNP
Volume
129
Issue
12
Year of publication
1999
Pages
2119 - 2122
Database
ISI
SICI code
0022-3166(199912)129:12<2119:COCIOS>2.0.ZU;2-7
Abstract
In rats fed cholesterol-rich diets, dietary casein vs. soybean protein rais es VLDL cholesterol concentrations. Because sphingomyelin may be an essenti al, structural component of VLDL, we tested whether casein feeding would ra ise VLDL-sphingomyelin. Rats were fed cholesterol-rich semipurified diets c ontaining either soybean protein (35 g/100 g) or casein for up to 21 d. Con sistent with previous work, casein consumption increased hepatic and VLDL c holesterol concentrations. Dietary casein also significantly raised the amo unt of sphingomyelin in the VLDL fraction, but this effect was transient. C asein feeding transiently lowered LDL- and HDL-2-sphingomyelin concentratio ns. We suggest that an increase in hepatic VLDL secretion after casein cons umption imposed an increased demand for sphingomyelin in the liver. The act ivity of key enzymes of sphingomyelin synthesis, i.e., serine palmitoyltran sferase, phosphatidylcholine:ceramide phosphocholinetransferase and phospha tidylethanolamine:ceramide phosphoethanolaminetransferase and sphingomyelin degradation, i.e., acid sphingomyelinase, were enhanced and depressed, res pectively, by casein consumption. Again these effects were transient. Thus, these data indicate that the extra sphingomyelin needed after short-term c asein feeding came about through enhanced rates of biosynthesis and reduced rates of degradation in the liver. In addition, plasma transfer of sphingo myelin from HDL-2 to VLDL might have contributed to the increase in VLDL sp hingomyelin in the casein-fed rats. This study shows that dietary casein vs . soybean protein transiently influences sphingomyelin metabolism in rats.