摘要:

The effect of ω-3 fatty acids derived from fish and marine mammals on subjects with normal glucose tolerance is still unclear. The aim of the present study was to test whether the hypolipidemia that follows the chronic administration of cod liver oil, rich in polyunsaturated fatty acids (ω-3), to normal rats is accompanied by changes in glucose metabolism, insulin secretion and sensitivity, and pancreatic insulin content. To achieve this goal, male Wistar rats were fed with a semisynthetic diet (w/w): 62.5% cornstarch, 7% cod liver oil plus 1% corn oil, and 17% protein (CD + CLO). Control rats were fed with the same semisynthetic diet with the only exception that the source of fat was 8% (w/w) corn oil (CD). Both diets were administered adlibitum for 1 month. At the end of the experimental period, the results obtained were as follows (mean ± SEM): serum triacylglycerol (mM): CD + CLO 0.21 ± 0.04 vs. CD 0.58 ± 0.05 (p < 0.05); free fatty acids (µM): CD + CLO 257 ± 20 vs. CD 288 ± 22 (p = NS); total cholesterol (mM): CD + CLO 1.13 ± 0.09 vs. CD 1.82 ± 0.06 (p < 0.05); high-density lipoprotein cholesterol (mM): CD + CLO 0.58 ± 0.08 vs. CD 1.07 ± 0.04 (p < 0.05); plasma glucose (mM): CD + CLO 6.30 ± 0.29 vs. CD 6.28 ± 0.10 (p = NS); liver triacylglycerol (µmol/liver): CD + CLO 104.1 ± 11.4 vs. CD 136.8 ± 4.3 (p < 0.05); glycogen (µmol/g wet weight): CD + CLO 298.3 ± 21.0vs.CD297.0 ± 19.0 (p = NS); glucose-6-phosphate dehydrogenase (U/liver): CD + CLO 37.9 ± 2.2 vs. CD 58.8 ± 5.0 (p < 0.05); triacylglycerol secretion (nmol/min/100 g body weight): CD + CLO 101.0 ± 2.0 vs. CD 166.0 ± 9.7 (p < 0.01); removal of fat emulsion (K2% min-1): CD + CLO 15.0 × 10-2 ± 0.8 ×10-2 vs.CD8.2 × 10-2 ± 0.2×10-2 (p < 0.01); intravenous glucose tolerance (kg 10-2):CD + CLO 2.68 ± 0.37 vs. CD 2.70 ± 0.14 (p = NS); immunoreactive insulin (µU/ml/ min): with the area under the curve between 0 and 30 min CD + CLO 544 ± 60 vs. CD 1,050 + 38 (p < 0.05), with the area under the curve between 0 and 60 min CD + CLO 1,188 ± 150 vs. CD 2,160 ± 137 (p < 0.05), and pancreas insulin content (mU/mg pancreas): CD + CLO 1.85 ± 0.29 vs. CD 2.04 ± 0.12 (p = NS). In conclusion, the present study shows that the strong hypolipidemic effect produced by the administration of low doses of fish oil to normal rats is accompanied by a significant reduction of plasma insulin levels without changes in glucose tolerance. Since no changes in pancreatic insulin content were observed, lower plasma insulin levels, both basal and after an intravenous glucose challenge, may be the result of an increased peripheral insulin

ISSN:0250-6807    

DOI:10.1159/000177897

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

In order to investigate whether previously reported effects of feeding olive oil (OO) upon rat serum lipid concentrations and immune cell functions are due to oleic acid, weanling rats were fed for 6 weeks on diets containing 20% by weight of OO, saf-flower oil (SO), or high oleic acid sunflower oil (HOSO); a low-fat (LF) diet containing 2.5% by weight of lipid was used as a control. Feeding the OO or HOSO diets resulted in an elevated serum triacylglycerol concentration as compared with feeding the LF or SO diets. The serum total cholesterol concentrations were raised in the animals fed the high-fat diets and were highest in animals fed the OO or the HOSO diet. The fatty acid composition of the serum and of spleen lymphocytes reflected that of the diet fed. The mitogen-stimulated spleen lymphocyte proliferation ex vivo was significantly lower following OO or HOSO feeding as compared with LF or SO feeding. Similarly, feeding the OO or the HOSO diet resulted in lower spleen natural killer cell activity as compared with LF or SO feeding. These observations indicate that the effects of OO feeding are most likely due to oleic acid rather than to other components of OO.

ISSN:0250-6807    

DOI:10.1159/000177898

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Aside from the well known alteration of Fe status in Fe deficiency, this condition has also a negative effect on the bio-availability of Ca and Mg. We studied the influence of the supplementation of a commercial cereal-milk formula with bovine blood on Fe, Ca, P, and Mg metabolism in control and Fe-deficient rats to investigate whether high Fe levels in diet produce some interactions and the possibility of decreasing these latter by a haem-Fe supplementation. The bioavailability in control and Fe-deficient animals was determined as the apparent digestibility coefficient and hemoglobin regeneration efficiency, both of which are accurate estimations of total Fe utilization. Non-fortified cereal-milk formula decreased the apparent digestibility coefficient of Ca and Mg in Fe-deficient rats; the concentrations of these minerals in liver, femur, and sternum were lower than in control animals. However, when the Fe content of the cereal-milk formula was doubled by supplementation with bovine blood, the adverse effects on the digestive utilization of Ca, and especially of Mg, were palliated, the concentration of these two minerals in the organs investigated increased, and the overall Fe status improved in Fe-deficient rats.

ISSN:0250-6807    

DOI:10.1159/000177899

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

Despite the abundance of n-3 polyunsaturated fatty acids, particularly docosahexaenoic acid (DHA), in the retina of all mammals, their role in vision remains unclear. However, the widely accepted notion that DHA is universally important in the retinal function was questioned in an earlier study (see text) involving guinea pigs, completely depleted of retinal DHA. The purpose of this study was to replicate this mammalian model of such deficiency and to determine any abnormalities in the electroretinogram. Guinea pigs were raised through three generations on 1 of 2 semipurified diets, containing different amounts of n-3 fatty acids, as determined by the supplementary oil which was the sole source of lipid in each diet. The added oils were safflower oil (n-6/n-3 = 72.0) or canola oil (n-6/n-3 = 2.5). Comprehensive electroretinographic assessment was conducted on guinea pigs, aged 6-9 weeks (safflower n = 13, canola n = 12), and retinae were extracted and the phospholipid fatty acid profile analyzed. Phospholipid fatty acid analysis revealed significant DHA deficiency (p < 0.001) in guinea pigs reared on the safflower oil diet (retinal DHA 2.5%) as compared with the canola oil group (retinal DHA 21.0%). Analysis of the electroretinogram showed significant reductions (p < 0.003) in both peak-to-peak and a-waves of safflower oil fed animals.

ISSN:0250-6807    

DOI:10.1159/000177900

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The purpose of this study was to evaluate the effects of different doses of dietary γ-linolenic acid (GLA) on the tissue phospholipid fatty acid composition and the synthesis of eicosanoids in growing rats. The supplementation with different oils rich in GLA (borage oil, evening primrose oil, or Spirulina oil) and poor in n-3 polyunsaturated fatty acids or biomass of Spirulina results in a significant dose-related increase of GLA and dihomo-GLA in liver, erythrocyte, and aorta phospholipids in rats fed during 6 weeks different levels of GLA. The arachidonic acid (AA)/dihomo-GLA ratios decreased with increasing intake of dietary GLA, but the AA proportions remained stable. The dietary administration of GLA increased the in vitro production by the aorta of prostaglandin E1· derived from dihomo-GLA, but did not significantly influence the production of prostaglandin E2 derived from AA by the aorta and the thromboxane B2 level in seru

ISSN:0250-6807    

DOI:10.1159/000177901

出版商:S. Karger AG    

年代:1996

数据来源: Karger

ISSN:0250-6807    

DOI:10.1159/000177902

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

The effects of the ingestion of 2 whole eggs (E), 2 egg whites, 2 egg yolks (Y), or no eggs with a standard breakfast on gastric emptying, glycemic and hormonal responses have been studied in 12 healthy young males. E and Y induce a significant delay of gastric emptying, together with reduced blood glucose and insulin peaks (Y). Egg ingestion, whatever the part, increases gastric inhibitory peptide level in blood. Cholecystokinin is enhanced after E or Y ingestion. The results indicate that egg ingestion, especially yolk ingestion, may be of interest in regulating metabolic variables of glucose metabolism.

ISSN:0250-6807    

DOI:10.1159/000177903

出版商:S. Karger AG    

年代:1996

数据来源: Karger

摘要:

To evaluate the short-term influence of fatty acids with different grades of saturation on insulin secretion and sensitivity, 8 healthy males (age 26 ± 3.5 years, body mass index 22.4 ± 1.8 kg/m2) were provided with 800 kcal daily of either carbohydrates (CH; 200 g), or fat (90 g) enriched either with saturated fatty acids (SAFA; 72%) or (ω-6) polyunsaturated fatty acids (PUFA; 60%) or cis-monounsaturated fatty acids (MUFA; 40%; n = 5) in addition to a standard diet (2,000 kcal/ day; 50% CH, 15% protein, and 35% fat; 33% SAFA, MUFA, and PUFA each) for 1 week in a randomized order (washout period 2 weeks). The stimulated insulin secretion was quantified by the frequently sampled intravenous glucose tolerance test (FSIGT; 0.3 g glucose/kg body weight), while the insulin sensitivity was determined by an euglycemic-hyperinsulinemic 5-mU clamp. In parallel, basal and stimulated carbohydrate and fat oxidation rates were estimated by indirect calorimetry. One week of defined fat exposure failed to significantly affect the glucose-induced insulin secretion during FSIGT and insulin-dependent glucose disposal during an euglycemic clamp (M values: CH 9.6 ± 1.6 mg/kg·min, SAFA 9.7 ± 2.2, PUFA 9.8 ± 2.5, and MUFA 11.5 ± 3.2 mg/kg·min; NS). In addition, oxidation rates for fat and glucose in the postabsorptive state and during hyperinsulinemia did not differ between the different diets. We conclude that short-term (1-week) isocaloric supplementation of a standard diet with fatty acids of varying degree of saturation does not affect either insulin secretion or insulin sensitivity in healthy men, due to the compensatory metabolic capacity of healthy

ISSN:0250-6807    

DOI:10.1159/000177904

出版商:S. Karger AG    

年代:1996

数据来源: Karger