Feeding purified sardine proteins

Serum HDL2 and HDL3 amounts and compositions are impaired in hypercholesterolemic rat fed highly on purified sardine protein despite unchanged lecithin: cholesterol acyltransferase activity

The effects of sardine protein on serum HDL2 and HDL3 amounts and compositions and lecithin: cholesterol acyltransferase (LCAT) activity were determined in growing rats fed highly on purified sardine proteins combined with 1% cholesterol + 0.5% cholic acid (Cc) for 21 days, in order to induce a hypercholesterolemic status (>3.9 mmol/L). At the end of this period, animals were randomly divided into 3 groups (n=6) receiving the following diets ad libitum for 28 days. Two groups were fed 20% on highly purified sardine protein (S) or 20% casein (C) and the third group continued to receive Cc diet. The results showed that the HDL3 amounts (which are the sum of apolipoproteins -apo- and lipids) and their apolipoprotein values were threefold lower in the C and S groups compared with Cc, whereas HDL3 - phospholipids (PL) and HDL3 - unesterified cholesterol (UC) values were similar in the 3 groups.
 
Compared to Cc group, rats fed on C and S diets exhibited higher HDL2 amounts (+39%) reflected mainly by increased HDL2 - cholesteryl esters (CE) - +90% and +80% respectively, whereas HDL2 - triacylglycerols (TG) concentration was significantly lower (-54%) only in the S group. However, LCAT activity represented 99.40±42.10, 148.24±46.54 and 112.72±14.59 nmol. mL.-1 h-1 in C, S and Cc group, respectively and remained unchanged in all groups.
 
In conclusion, feeding purified sardine proteins probably causes an efficient flow of UC from tissues to plasma via the HDL2-rich EC. Indeed, the higher level of HDL2-EC could probably create a gradient necessary for this transfer, involving thus a high efficacy of reverse cholesterol transport.

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