| Summary: | 碩士 === 輔仁大學 === 食品營養學系 === 84 ===
The study was conducted to investigate the effects of stort-(8 weeks) or long-term (26 weeks) feeding of phospholipids on plasma and liver lipids' levels. The efficiencies of adding lecithin precursors, methionine and/or choline, compared with lecithin and the effect of essential fatty acid (EFA) on plasma and liver lipids were also studied.
Weaned male Wistar rats were randomly divided into 8,5 and 2 dietary groups, 6 in each, for trials I, II and III respectively. The basal diet was based on AIN-76 synthetic diet with slight modification. The casein in AIN-76 diet was replaced by soy-protein which is low in methionine. The methionine was not added and the choline was reduced to 0.1%. While the feed was fortified with 1% cholesterol for the purpose of easy comparisons of its generated hyperlipemic and fatty liver.
Trial I: This experiment fed soybean and corn oils rich in EFA or hydrogenated beef tallow and palm oil containing less EFA for the comparisons of effect of various saturation of fat on the accumulation of plasma and liver lipids. Also observed how the long-term high fat diet and deficiency of methionine, choline conditions affect the plasma and liver lipid accumulation.
Trial II: It probed into whether the constant given precursors of lecithin, methionine and/or choline, affect the plasma and liver lipid accumulation similar to direct in take of phospholipids.
Trial III:It covered the role of essential fatty acid on plasma and liver lipid's metabolism, under feeding with all saturated fats (nearly no EFA), or supplementing with 2% CORN OIL (neough EFA). After 8 or 26 weeks feeding, all rats were fasted overnight and killed for serum and liver lipids analyzed and liver sections.
The results of trial I showed that both short-and long-term feeding of phospholipids in soybean oil diets did not affect the plasma total lipids, cholesterol, high density lipoprotein-cholesterol (HDL-C) or phospholipids. It was, however, observed that the plasma triacylglycerol (TG) was reduced by 8 weeks feeding of dietary phospholipids (p<0.05). It was noted that phospholipids in hydrogenated beef-tallow diet significantly decreased plasma total lipids, TG, cholesterol, and phospholipids to the levels closed to the ones in soybean oil groups in both short and long term groups (p<0.05). Furthermore, it slightly enhanced plasma HDL-C (p<0.10). Data from biochemical analyses and slide observation, the diet largely redued liver total lipids, TG and cholestol (p<0.01). It was found that the Iccumulation of liver total lipids was higher in rats fed for 26 weeks than the ones for 8 weeks (p<0.05). Data also revealed that feeding phospholipids in soybean oil diet for 26 weeks increased liver phospholipids (p<0.05).
The results of trial II demonstrated that feeding phospholipids high in soybean oil diet reduced the plasma cholesterol and TG of the rats (p<0.05). Moreover, it decreased the liver total lipid, TG and cholesterol (p<0.05). However, with added methionine or methionine or methionine and choline, a depression of the plasma and liver TG, but not other lipids, was noted in this study. Slide observation discovered that the liver lipid accumulation in the group with added methionine or methionine and choline, was lower than the one in control group; however, compared with added phospholipids there was less significant reduction in liver lipid accumulation.
The results of trial III revealed that the rats fed EFA-adequate diet (TCo group) or EFA-deficient (TPo group), did not show any effect on the plasma total lipids, TG, cholesterol, HDL-C or phospholipids. Feeding EFA diet didn'kt show a reduction on liver total lipids, TG or phospholipids, either. On the other hand, it increased liver cholesterol over the EFA-deficient diet (p<0.05)
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