Effects of fish oil- and olive oil-rich diets on iron metabolism and oxidative stress in the rat.

The objective of the present study was to examine the effects of fish oil (FO)- and olive oil (OO)-rich diets on Fe metabolism and oxidative stress. Rats were fed for 16 weeks with diets containing 50 g lipids/kg; either OO, maize oil (MO) or FO. OO or MO diets contained a standard amount (100 mg/kg) of all-rac-alpha-tocopheryl acetate. FO diets were supplemented with 0, 100 or 200 mg all-rac-alpha-tocopheryl acetate/kg (FO-0, FO-1 or FO-2 diets, respectively). At the end of the feeding period, we measured non-haem Fe stores in liver and spleen, and erythrocyte and reticulocyte count. We also determined antioxidants and products derived from lipid peroxidation in plasma and erythrocytes. Our results showed reduced non-haem Fe stores in rats fed any of the FO diets. Reticulocyte percentage was higher in the rats fed FO-0 and FO-1. Plasma alpha-tocopherol was very low in rats fed the FO-0 diet. Rats fed the FO-1 and FO-2 diets showed higher alpha-tocopherol in plasma than the FO-0 group but lower than the MO or OO groups. We did not observe such differences in the alpha-tocopherol content in erythrocyte membranes. Superoxide dismutase and glutathione peroxidase activities were lower in the erythrocytes of rats fed the FO-0 diet. The products derived from lipid peroxidation were also higher in the FO groups. The administration of FO-rich diets increased lipid peroxidation and affected Fe metabolism. On the other hand, the OO-rich diet did not increase oxidative stress and did not alter Fe metabolism. Based on these results, we conclude that FO supplementation should be advised carefully.

A flavonoid-rich diet increases nitric oxide production in rat aorta.

1. Red wine intake is associated with a low risk of cardiovascular disease. This effect has been partly attributed to the action of polyphenolic compounds, which decrease the oxidation of plasma low density lipoproteins. Moreover, nitric oxide ((*)NO) is a vasodilator and polyphenolic compounds induce endothelium-dependent vasorelaxation in vitro. 2. Here we studied whether a diet rich in dealcoholated red wine (DRW) increases acetylcholine-induced vasorelaxation and whether ingestion of DRW-, quercetin- or catechin-rich diets modifies the (*)NO-cyclic guanosine-3',5'-monophosphate (cyclic GMP) pathway and superoxide anion (O2(.-)) release in aorta in a resting state in rats fed semi-purified diets containing either 35% (v w(-1)) DRW, 0.3% (w w(-1)) quercetin or 0.3% (w w(-1)) catechin for 10 days. 3. (*)NO-mediated vasorelaxation induced by acetylcholine was greater in rats fed the DRW-rich diet than in those that received the control diet. 4. Expression of endothelial (*)NO synthase (eNOS) was similar in the four dietary groups. The aortic rings of rats fed either the DRW-, quercetin-, or catechin-rich diets showed higher NOS activity, (*)NO production and cyclic GMP content than those of rats fed the control diet. No changes were observed in O2(.-) production. 5. In summary, diets rich in either DRW, quercetin or catechin induced endothelium-dependent vasorelaxation in rat aorta in a resting state through the enhancement of (*)NO production, without modifying O2(.-) generation, thus the bioavailability of (*)NO was increased. The increase in the (*)NO-cyclic GMP pathway explains the beneficial effect of flavonoids at vascular level.

Fatty acid composition of erythrocyte membranes affects iron absorption in rats.

We studied the influence of the fatty acid composition of three different diets on iron absorption in relation to the lipid peroxidation of the erythrocyte membranes. After weaning, three groups of rats were fed isoenergetic semipurified diets for 16 wk: control diet (containing canola oil and peanut oil), tripalmitin diet (a saturated fatty acid diet) and a sardine oil diet rich in polyunsaturated fatty acids. Eight rats from each group were administered 59FeSO4 by gastric intubation for ferrokinetic studies, and six rats from each group were used for several analyses in blood, liver, spleen and erythrocytes. Results obtained from 59Fe eliminated in feces and 59Fe present in plasma, both calculated by the area under the curve and from maximum concentration in plasma, indicated that the sardine oil diet induced higher iron absorption than the control diet. The lipid peroxidation of erythrocyte membranes in rats fed sardine oil was higher than that in control rats due to high membrane's (n-3) polyunsaturated fatty acid content and low alpha-tocopherol level. The 59Fe in liver and spleen of rats fed the sardine oil diet was higher than in rats fed the control diet, and 59Fe was diverted to erythrocytes to a greater extent than in rats fed the control diet due to their reduced life-span. The sardine oil diet, by lessening alpha-tocopherol and raising the degree of lipid peroxidation in erythrocytes, augments iron absorption, whereas the tripalmitin diet, by protecting erythrocyte membranes from lipid peroxidation, leads to a lower rate of iron absorption.

Effect of degree of unsaturation in dietary fatty acids on arachidonic acid mobilization by peritoneal macrophages.

Cells from rats fed with a tripalmitin diet showed a depletion of phospholipid arachidonate and n-3 fatty acids such as eicosapentaenoic and docosahexaenoic acids (EPA and DHA). In rats fed fish oil diet, a significant reduction in arachidonic acid (AA) content was observed whereas EPA and DHA were incorporated into membranes lipids. These changes in lipid composition of membranes did not affect cellular adherence, phagocytic capability, or [3H]AA incorporation. However, both tripalmitin and fish oil diets induced a decrease in [3H]AA mobilization stimulated by 4 beta-phorbol-12-myristate 13-acetate, A23187, or opsonized-zymosan in rat peritoneal macrophages. These results demonstrate that the antiinflammatory effects of essential fatty acids deficiency or n-3 enrichment diets may be associated with a decreased AA mobilization in resident rat peritoneal macrophages treated with proinflammatory agents.

Iron absorption by small intestine of chickens.

Iron (Fe) absorption by three segments (duodenum, jejunum, and ileum) of the small intestine of chickens was studied by a perfusion technique in vivo in closed circuit using 59Fe Cl3 and was related to the histological characteristics of each segment. The serosal transfers of Fe for the duodenum and jejunum were the same (14%/cm), but significantly different (p < 0.05) from those of the ileum (9%/cm), which may be explained by the morphological and histological properties of the gut of chickens. However, the presence of Fe in blood and in liver was significantly lower after perfusion of the jejunum and ileum than after perfusion of the duodenum. It is concluded that chickens show an early adaptation of small intestine to Fe absorption in response to the considerable loss of Fe suffered during the laying process.

Carrageenan-induced granuloma and iron status in rats with dietary polyunsaturated fatty acid deficiency.

Sprague-Dawley rats were fed for 4 months on a control diet or a polyunsaturated-fatty-acid (PUFA)-deficient diet. The combined effects of iron overload (Fe dextran) or Fe deficiency (desferrioxamine) on carrageenan-induced granuloma were studied. PUFA deficiency induced changes in Fe metabolism, but no alterations in lipid peroxidation variables were observed. Inflammation implied an increase in lipid peroxidation, Fe storage and caeruloplasmin concentration, together with symptoms of anaemia. PUFA deficiency in inflamed rats gave rise to a lower inflammatory response (granuloma weight and prostaglandin E2 concentration) and ethane exhalation. Fe overload potentiated inflammatory and lipid peroxidation processes, whereas Fe deficiency decreased them.

Modulation of exudate inflammation parameters in rat carrageenan-induced granuloma by modification of exudate iron levels.

We have used the carrageenan-induced pouch-granuloma in rats to investigate how changes in low-molecular-mass iron chelate levels in the exudate, induced by iron loading (iron-dextran) or chelation (desferrioxamine) influence cellular and systemic inflammatory parameters. In the iron-treated group we observed a rapid decrease in the number of leukocytes and exudate volume; there was also an increase in ferritin iron and low-molecular-mass iron chelates, and on the eighth day a systemic response. In the desferrioxamine-treated group we detected a decrease in low-molecular-mass iron chelates, ferritin iron, and an increase in the number of leukocytes. We describe the protective effects of desferrioxamine against the deleterious effects of ferrous iron and relate this to its chelating and scavenging activity. The results suggest that the levels of low-molecular-mass iron chelates modulate the inflammatory response, possibly through their contribution to the oxygen free radical generation, which is responsible for the cell membrane damage and subsequently its death. The modulatory action of iron-dextran and desferrioxamine support our hypothesis.

Sexual and age variations of organ iron content in Shaver chickens.

1. Haematological values and iron content in liver, spleen, kidneys and intestine were determined in Shaver chickens of both sexes at 4, 8, 13 and 18 weeks and in females at 24 weeks (the beginning of the laying period). 2. The haematocrit decreased significantly in laying compared with non-laying females and the haemoglobin concentration was similar to that in the prelaying state. Plasma iron in laying females increased to four times the basal value at 13 weeks. 3. Females of 13 and 18 weeks (prelaying state) stored more iron than males at the same age. A simultaneous liver and spleen mobilisation of stored iron and increased intestinal iron accumulation took place in the laying process. The haematological variables examined were minimally altered. 4. The iron contents of both heart and kidneys were influenced by age and followed a linear trend, except that in the heart of females where a quadratic response was observed.

Organ iron content in New Hampshire chickens.

We have studied some hematological parameters and iron and ferritin iron contents in different organs of New Hampshire chickens at the ages of 4, 8, 13, and 18 wk for both sexes, as well as 24 wk for laying hens, in order to study the variations with age, the existence of sex differences, and the accommodations to laying. The hematocrit and hemoglobin levels did not show important variations, but plasma iron increased at laying. The iron and ferritin iron concentrations in liver and spleen increased more slowly during growth than the total iron and ferritin iron contents, and no significant decline was observed at laying. The iron concentration in the heart and pectoral muscle stayed constant throughout the period studied, and kidneys showed slight increase with age. However, the iron concentration in the intestine decreased from the proximal to the distal segments and also increased in the duodenum at laying. No differences caused by sex have been detected in the organs studied. The absence of differences caused by sex in the organ iron stores in favor of females, especially in liver, and the lack of influence of the laying process in iron stores could be a consequence of the low laying frequency of this strain.

Role of iron in carrageenan-induced granuloma: action of desferrioxamine and indometacin.

Iron has been implicated in the inflammatory process. In this paper we studied the modulating inflammatory activity of iron in the carrageenan-induced granuloma pouch, taking indometacin as a standard anti-inflammatory drug. Sprague-Dawley rats were injected subcutaneously with desferrioxamine (100 mg/kg) and indometacin (5 mg/kg) for 3 consecutive days before granuloma induction, followed by a daily administration in the granuloma pouch until the day before death. We determined the granuloma weight and assayed in the exudate: volume, number of leukocytes, PGE2 levels and loosely bound iron content at 1 (acute inflammation) and 6 days (chronic inflammation) after granuloma induction. Our results show a dual effect of desferrioxamine, inflammatory in the acute phase and anti-inflammatory in the chronic phase. These results are discussed in relation to chemotaxis and to the potential role of iron on oxygen free radical production, collagen synthesis and hydroperoxide generation, while indometacin acts through the cyclooxygenase pathway.

Iron mobilization in three animal models of inflammation.

The effect of acute, subchronic, and chronic experimental models of inflammation upon hematocrit, hemoglobin, serum iron and ferritin iron and nonheme iron concentration in the liver and spleen has been studied in the rat. In the acute model (carrageenan oedema) no iron mobilization took place, whereas in the chronic models differences in iron mobilization were observed, related to their different chronicity and to the time elapsed from induction. The carrageenan-induced granuloma (from 12 h to 8 days) (subchronic model) was accompanied by a decrease of plasma iron (12 and 24 h), a later decrease of the hematocrit values (2 and 4 days) and high ferritin and nonheme iron concentrations in the liver and spleen for 4 days, followed by a tendency to return to the control values. The anemia in the adjuvant arthritis (from 1 to 4 weeks after induction) (chronic model) was observed at 7 days and is related to increased iron stores in the liver and spleen. However, the iron store levels in liver decreased and fell later below control values. The increase of ferritin and nonheme iron concentrations may be responsible for the reduced availability of iron release from tissue.

Body and egg iron content in shaver and New Hampshire chickens.

1. A comparative study on the iron content in internal organs (blood, liver, spleen, kidneys and heart), carcass and feathers, as well as on the whole iron content has been carried out at different ages (4, 8, 13, 18 and 24 weeks), on two chicken breeds (shaver and New Hampshire). 2. The iron content in internal organs in shaver was higher than in New Hampshire. 3. A tendency of the iron content in the carcass to decrease with age has been observed for both breeds; values were higher for laying shaver hens. 4. The egg-producing strain, shaver, showed a greater iron status with a stable body iron content from 13 weeks on (53-55 ppm), permitting a constant laying frequency (90%) during an 18-month period, with only a small reduction of egg iron content from 33.8 to 31 ppm. 5. The whole body iron decreased progressively with age in the New Hampshire broiler strain to 42-49 ppm iron, and the laying process sharpened this tendency. A drastic reduction in laying, accompanied by a lower egg iron content (28.9 ppm iron), was observed. 6. Iron data obtained in the present paper reflect the specific genetic adaptation to egg production of the shaver strain.

Intestinal iron absorption in chickens : I. Experimental conditions.

Intestinal iron absorption in chickens was studied in vivo, using an intestinal perfusion technique in closed circuit.The results obtained show that iron absorption, at 30 min intervals, is a linear function of test solution iron concentrations of up to 776 µg Fe/20 mL. At higher concentrations, iron saturation occurs. The mucosal epithelial cells seem to be less a limiting factor than in rats. However, in chickens, the binding capacity of plasma might play an important role in the regulation of iron absorption.Iron absorption versus time was analyzed in 15, 30, 60, and 120 min periods for the iron concentration of 14 µg Fe/20 mL. Intestinal iron absorption showed a linear relationship between these two parameters.A period of perfusion of either 30 or 60 min by a solution of 14 µg Fe/20 mL appears suitable since no interference by a saturation process can then occur.

Intestinal iron absorption in chickens : II. Effect of sex.

Sexual differences in intestinal iron absorption in Shaver and New Hampshire chickens strains was analyzed with an in vivo perfusion technique in closed circuit. In 6-week-old Shaver chickens, a significantly higher rate was found in females.A comparison of the absorption rates between adult males and laying and nonlaying hens from the New Hampshire strain, showed a significant increase of the net transfer during the laying period. However, we did not find any differences between males and nonlaying hens. From our data, a thicker intestinal wall seemed evident in the adult females, with highest values during laying.Estrogen administration in male chickens increased the plasma iron and produced a defensive reaction to iron absorption. However, during the laying stage, high plasma levels were found to be tied to higher absorption rates.Iron storage in females is higher in proportion to the increase of iron absorption, which is enhanced during the laying period. Estrogen appears to mediate this process, but from present data the point of action has not yet been identified.