EFA-deficient Diet Research Articles

Maternal essential fatty acid deficiency depresses serum leptin levels in suckling rat pups

Dietary lipid quantity and quality have recently been shown to affect serum leptin levels in adult rats. Moreover, suckling pups from dams fed a high fat diet had increased serum leptin levels. The aim of the present study was to analyze the influence of essential fatty acid (EFA) deficiency on serum leptin levels in dams and their pups during the suckling period. For the last 10 days of gestation and throughout lactation, pregnant rats were fed a control or an EFA-deficient (EFAD) diet. The levels of leptin and EFA in the serum of the dams and pups were analyzed 1, 2, and 3 weeks after delivery. In parallel, serum levels of glucose and corticosterone were analyzed in the pups. Low serum leptin levels were found in the control lactating dams during the entire lactation period compared with the age-matched nonlactating animals. The leptin concentrations in the lactating dams fed the EFAD diet were lower compared with those fed the control diet. The serum leptin levels of suckling pups from dams on the EFAD diet were markedly decreased compared with controls (P < 0.05). The reduced serum leptin levels could not be explained by nutritional restriction as evaluated by serum levels of glucose and corticosterone. These results indicate the importance of the EFA composition of the maternal diet for serum leptin levels in both dams and pups. EFA deficiency in lactating dams may cause long-term effects on the pups through dysregulation of leptin and leptin-dependent functions. —Korotkova, M., B. Gabrielsson, L. Å. Hanson, and B. Strandvik. Maternal essential fatty acid deficiency depresses serum leptin levels in suckling rat pups.

Alteration of liver and muscle fatty acid composition in gilthead seabream “Sparus aurata” juveniles held at high stocking density and fed an essential fatty acid deficient diet

The aim of the present study was to determine the combined effect of both stress and EFA deficiency on several biological and biochemical parameters. Fish were fed during 15 weeks two isocaloric and isoproteic diets: a control diet based on fish oil and formulated to meet the n-3 HUFA requirements for this species (1.5% of n-3 HUFA) and a deficient diet containing beef tallow and formulated to be deficient in n-3 HUFA. Each experimental diet was evaluated both at high and low stocking densities (10 and 3.2 kg m −3 of initial density, respectively). High stocking density produced a chronic stress situation with elevation of plasma cortisol levels. It also caused a reduction in hepatosomatic index and liver lipid contents, increasing the oleic acid/n-3 HUFA ratios in the polar lipids. Fish fed the EFA deficient diet at low stocking density showed common deficiency symptoms. High stocking density in fish fed the EFA deficient diet induced a higher degree of EFA deficiency symptoms leading to mortality, liver steatosis, liver lipid deposition, reduced muscle lipid and reduced n-3 HUFA contents, which particularly affected EPA, but not DHA, suggesting a preferential retention of the latter fatty acid, specially in the phosphoglycerides fraction.

Relationship between covalently bound ceramides and transepidermal water loss (TEWL).

The stratum corneum, which is the outermost layer of the skin, functions as an important barrier to maintain biological homeostasis. The multilamellar structures formed by intercellular lipids present in the stratum corneum are considered to play an important role in barrier function. Most intercellular lipids are unbound and can be extracted by organic solvents, but some intercellular lipids are covalently bound to cornified envelope proteins. Decreases in unbound lipid levels reduce the barrier function of the stratum corneum, but the relationship between bound lipid and the barrier function of the stratum corneum is not well understood. In this study, we examined the relationship between the amount of covalently bound ceramide, the main bound lipid, and the barrier function of the stratum corneum. A single dose of UVB irradiation (2 x MED), or continuous UVB irradiation (0.5 x MED/day for 14 days) to the back, or feeding with an essential fatty acid-deficient (EFAD) diet for 8 weeks caused a significant elevation of TEWL and a significant reduction in covalently bound ceramides in hairless rats. Transmission electron microscopy revealed that the intercellular multilamellar structures in the stratum corneum of treated rats were incomplete (folding, defects, unclear images) compared to the structures seen in the stratum corneum of non-UVB-irradiated and non-EFAD rats. These results suggest that the amount of covalently bound ceramides is highly correlated with the barrier function of the skin, and that covalently bound ceramides play an important role in the formation of lamellar structures, and are involved in the maintenance of the barrier function of the skin.

Essential fatty acid deficiency affects the fatty acid composition of the rat small intestinal and colonic mucosa differently

The intestinal mucosal fatty acid (FA) composition was investigated in Sprague–Dawley rats after 7 and 23 weeks on an isocaloric diet with qualitatively different essential fatty acid (EFA) composition. For comparison, serum and red blood cell (RBC) membranes were investigated in parallel. The molar percentage of most FAs differed significantly between serum and RBC membranes both in controls and rats fed an EFA deficient (EFAD) diet. The influence of the EFA diet was similar on serum and RBC membrane phospholipids except for arachidonic acid (AA) which was more markedly decreased in serum than in RBC membranes. The FA composition was similar in ileal and colonic mucosa, markedly differing from the jejunal mucosa, in which the AA concentration was lower (13.0±0.8 versus 16.8±0.5 and 15.7±2.8 mol%) and the linoleic acid (LA) concentration higher (34.0±1.6 versus 17.8±1.3 and 15.5±2.8 mol%, respectively). The EFAD diet induced a more than five-fold decrease in the jejunal and ileal concentration of LA from 33.9±1.6 to 6.0±1.5 mol% and 17.8±1.3 to 2.1±0.7 mol%, respectively. AA decreased more in the ileal and colonic mucosa than in the jejunum. The changes in the FA composition of the intestinal compartments after EFAD diet were different from that in serum and RBC membranes, and did not further change after 23 weeks compared to 7 weeks after introduction of the diet. The study shows that dietary influences are tissue specific and serum or RBC membranes do not mirror local changes in any of the different intestinal segments.

Docosahexaenoic and Arachidonic Acid Prevent a Decrease in Dopaminergic and Serotoninergic Neurotransmitters in Frontal Cortex Caused by a Linoleic and α-Linolenic Acid Deficient Diet in Formula-fed Piglets

This study examined the effects of diets deficient (D) in linoleic [18:2(n-6)] and linolenic acid [18:3(n-3)] at 0.8 and 0.05% energy, respectively, or adequate (C) in 18:2(n-6) and 18:3(n-3) at 8.3 and 0.8% energy, respectively, without (−) or with (+) 0.2% energy arachidonic [20:4(n-6)] and 0.16% energy docosahexaenoic [22:6(n-3)] acid in piglets fed from birth to 18 d. Frontal cortex dopaminergic and serotoninergic neurotransmitters and phospholipid fatty acids were measured. Piglets fed the D− diet had significantly lower frontal cortex dopamine, 3,4-dihydroxyphenylacetic (DOPAC), homovanillic acid (HVA), serotonin and 5-hydroxyindoleacetic acid (5-HIAA) concentrations than did piglets fed the C− diets. Frontal cortex dopamine, norepinephrine, DOPAC, HVA, serotonin and 5-HIAA were higher in piglets fed the D+ compared to those fed the D− diet (P < 0.05) and not different between piglets fed the D+ and those fed the C− diets or the C− and C+ diets. Piglets fed the D− diet had lower frontal cortex phosphatidylcholine (PC) and phosphatidylinositol (PI) 20:4(n-6) and PC and phosphatidylethanolamine (PE) 22:6(n-3) than did piglets fed the C− diet (P < 0.05). Piglets fed the D+ diet had higher frontal cortex PC and PI 20:4(n-6) and PC, PE, PS and PI 22:6(n-3) than did piglets fed the D− diet. These studies show that dietary essential fatty acid deficiency fed for 18 d from birth affects frontal cortex neurotransmitters in rapidly growing piglets and that these changes are specifically due to 20:4(n-6) and/or 22:6(n-3).

Effects of essential fatty acid-deficient diets on growth, mortality, tissue histopathology and fatty acid compositions in juvenile turbot (Scophthalmus maximus)

Three diets in which the lipid component was supplied either as fish oil (FO), linseed oil (LO) or olive oil (OO) were fed to duplicate groups of juvenile turbot (Scophthalmus maximus) of initial weight 1.2 g for a period of up to 12 weeks. The latter two diets resulted in a significant reduction in specific growth rate and an increased mortality compared to the FO (control) fed fish. A liver histopathology was evident in around half of the fish fed the LO and OO diets but was absent in fish fed FO. The lesion showed indications of cellular alterations consisting of foci of densely basophilic cells but without evidence of inflammatory activity. The total lipid fatty acid composition of the carcass from fish fed LO had increased percentages of 18:2n-6 and 18:3n-3, but decreased percentages of all other polyunsaturated fatty acids (PUFA) including the physiologically important 20:4n-6, 20:5n-3 and 22:6n-3, compared to fish fed FO. Almost 2/3 of the total fatty acids in the carcass of OO-fed fish were monounsaturated while the percentages of total saturated fatty acids and all other PUFA, except 18:2n-6, were significantly reduced compared to fish fed FO. Broadly similar effects on total lipid fatty acid composition were observed in liver. In the liver glycerophospholipid classes of fish fed LO, percentages of 18:2n-6, 18:3n-3 and 20:3n-3 were significantly increased whereas all C20 and C22 PUFA, with the exception of 20:5n-3 in PI, were significantly reduced compared to fish fed FO. The liver glycerophospholipids of fish fed OO all showed significantly increased total monounsaturates, 18:2n-6, 20:2n-6, 18:2n-9 and 20:2n-9 as well as reduced percentages of 20:4n-6 and 22:6n-3, compared to fish fed FO. The brain glycerophospholipids showed broadly similar changes in response to dietary treatment although the magnitude of fatty acid alterations was less than those observed in liver. The greater mortalities in the OO-fed fish compared to the LO-fed fish suggests that incorporation of 18:3n-3 into tissue phospholipids can offset losses of long-chain PUFA more effectively than incorporation of 18:1n-9. However, levels of dietary long-chain PUFA must be optimised to allow normal growth and development. We conclude that the very low flux through the fatty acid desaturase/elongase pathways in turbot is not up-regulated by diets deficient in 20:5n-3 and 22:6n-3.

Dietary n-6 and n-3 fatty acids in immunity and autoimmune disease.

Clearly there is much evidence to show that under well-controlled laboratory and dietary conditions fatty acid intake can have profound effects on animal models of autoimmune disease. Studies in human autoimmune disease have been less dramatic; however, human trials have been subject to uncontrolled dietary and genetic backgrounds, infection and other environmental influences, and basic trial designs have been inadequate. The impact of dietary fatty acids on animal autoimmune disease models appears to depend on the animal model and the type and amount of fatty acids fed. Diets low in fat, essential fatty acid-deficient, or high in n-3 fatty acids from fish oils increase the survival and reduce disease severity in spontaneous autoantibody-mediated disease, whilst linoleic acid-rich diets appear to increase disease severity. In experimentally-induced T-cell-mediated autoimmune disease, essential fatty acid-deficient diets or diets supplemented with n-3 fatty acids appear to augment disease, whereas n-6 fatty acids prevent or reduce the severity. In contrast, in both T-cell and antibody-mediated auto-immune disease the desaturated and elongated metabolites of linoleic acid are protective. Suppression of autoantibody and T lymphocyte proliferation, apoptosis of autoreactive lymphocytes, and reduced pro-inflammatory cytokine production by high-dose fish oils are all likely mechanisms by which n-3 fatty acids ameliorate autoimmune disease. However, these could be undesirable long-term effects of high-dose fish oil which may compromise host immunity. The protective mechanism(s) of n-6 fatty acids in T-cell- mediated autoimmune disease are less clear, but may include dihomo-gamma-linolenic acid- and arachidonic acid-sensitive immunoregulatory circuits such as Th1 responses, TGF beta 1-mediated effects and Th3-like responses. It is often claimed that n-6 fatty acids promote autoimmune and inflammatory disease based on results obtained with linoleic acid only. It should be appreciated that linoleic acid does not reflect the functions of dihomo-gamma-linolenic and arachidonic acid, and that the endogenous rate of conversion of linoleic to arachidonic acid is slow (Hassam et al. 1975, 1977; Phylactos et al. 1994; Harbige et al. 1995). In addition to effects of dietary fatty acids on immunoregulation, inflammation as a consequence of immune activation in autoimmune disease may also be an important mechanism of action whereby dietary fatty acids modulate disease activity. In conclusion, regulation of gene expression, signal transduction pathways, production of eicosanoids and cytokines, and the action of antioxidant enzymes are all mechanisms by which dietary n-6 and n-3 fatty acids may exert effects on the immune system and autoimmune disease. Probably the most significant of these mechanisms in relation to our current understanding of immunoregulation and inflammation would appear to be via fatty acid effects on cytokines. The amount, type and balance of dietary fatty acids and associated antioxidant nutrients appear to impact on the immune system to produce immune-deviation or immunosuppressive effects, and to reduce immune-mediated inflammation which will in turn affect the susceptibility to, or severity of, autoimmune disease.

Changes in the activities of three diagnostic enzymes in the heart of rats following the consumption of diets deficient in zinc and essential fatty acids.

Changes in the activities of alkaline phosphatase (ALP), lactate dehydrogenase(LDH) and glutamate dehydrogenase (GDH) in the heart following the consumption of diets deficient in zinc and essential fatty acids (EFA) by rats were investigated. The study was a 2 x 2 factorial design in which rats were fed diets deficient in zinc (5 micrograms/g) or EFA (4% hydrogenated coconut oil) or both. The control diet was adequate in both zinc (100 micrograms/g) and EFA (4% soybean oil). The experimental diets were fed for forty-two days after which time the activities of the enzymes were terminally determined in the heart of the rats. The result showed that the activity of ALP was markedly elevated in rats consuming either zinc or EFA deficient diet and slightly in the group deficient in both EFA and zinc. LDH and GDH activities were significantly depressed by EFA only. An interactive effect of zinc and EFA was indicated only for ALP activity. The data indicate a resistance of cardiac tissue to moderate zinc deficiency. However, the effects of EFA were apparent.

ESSENTIAL FATTY ACID DEFICIENCY DIFFERENTLY AFFECTS THE FATTY ACID COMPOSITION OF THE RAT INTESTINAL AND COLONIC MUCOSA.

223 The gastro-intestinal tract is involved in the first stage of fatty acid(FA) consumption, as well as in immunological reactions such as development of tolerance or allergy. We analysed the FA patterns in the mucosa of the intestine and colon in two groups of rats: 1) Sprague Dawley female rats were fed a reference diet: 2) similar rats received an essential fatty acid deficient (EFAD) diet during 6 weeks. We analysed the relative FA composition in phospholipids (PLs) by gas-liquid chromatography in serum, erthrocyte (RBC) membranes and intestinal mucosa of jejunum, ileum and colon. We found changes in arachidonic acid (AA, 20:4, n-6) levels in RBC membrane PLs and serum PLs following EFAD diet (p<0.005).TableTable: The molar percentage of EFA in PLs of normal and EFAD rats (%)We revealed more pronounced changes of the AA in serum PLs than in RBC membrane PLs. At the same time the FA 20:3 portion in serum PLs became significantly more elevated than in RBC PLs (p<0.005). We assume that the composition of FAs in membrane PLs is more stable. Membrane PLs might be one of the main sources of EFA during a prolonged deficient state. We found for normal rats that the FA composition was almost the same for ileal and colonic mucosa, but differed drastically for jejunal mucosa. The portion of AA in jejunal mucosa was lower than in ileal mucosa, but the level of linoleic acid(LA, 18:2, n-6) was significantly higher (p<0.005). The EFAD diet induced a profound fall of LA in rat jejunal mucosa (p<0.005), whereas the relative proportion of AA remained normal. Morphological signs of EFA deficiency were more expressed in the ileal mucosa that the jejunal mucosa. At the same time, both AA and LA were strikingly decreased in ileal mucosa of EFAD rats(p<0.005). Simultaneously, the relative levels of 20:3 (n-9) and 18:1 (n-9) were increased. Similar changes were found in the ileal and colonic mucosa. EFAD diet seemed to cause more significance disturbances in the ileal and colonic mucosa than in the jejunal mucosa.

Dietary fish oil inhibits Δ6‐desaturase activity in vivo

AbstractLiver Δ6‐desaturase activity was determined in mice which were made deficient in (i) n‐6 and n‐3 polyunsaturated fatty acids (PUFA), (ii) n‐6 PUFA, or (iii) arachidonic acid (AA). Initially, the mice were subjected to two cycles of a fasting (1 d)/refeeding (2–3 d) protocol in which they were refed an essential fatty acid‐deficient (EFAD) diet during the refeeding period. This 1‐wk fasting/refeeding protocol, referred to as F/R EFAD, produced a rapid and substantial decline in tissue n‐3 and n‐6 PUFA and a corresponding increase in n‐9 fatty acids, notably oleic acid and Mead acid (20:3n‐9). Combined liver Δ6‐desaturase/elongase/Δ5‐desaturase activities in vivo were quantified by measuring the conversion of 14C‐linoleic acid (LA) to 14C‐AA in mouse liver. Although F/R EFAD caused, as expected, a substantial decline in liver AA and LA content, the conversion of 14C‐LA to 14C‐AA was the same in these mice as in chow‐fed controls (approximately 33–34%). Subsequent refeeding of F/R EFAD mice with an EFAD diet, supplemented with corn oil, restored tissue n‐6 PUFA levels without altering the conversion of 14C‐LA to 14C‐AA. In contrast, refeeding with an EFAD diet, supplemented with fish oil, inhibited 14C‐LA to 14C‐AA conversion by 78%. Significantly, inhibition of conversion of 14C‐LA to 14C‐AA was maintained in F/R EFAD mice that were subsequently fed an EFAD diet supplemented with a 1:1 mixture of fish oil/corn oil. This latter protocol yielded a unique liver fatty acid composition in which AA was selectively depleted, whereas LA and the n‐3 PUFA were increased. The data suggest that dietary n‐3 C20–22 PUFA negatively regulate the in vivo synthesis of n‐6 PUFA at the level of the Δ6‐desaturase.

Fragmentation of the Distal Portion of Tomes' Processes of Secretory Ameloblasts in the Forming Enamel of Rat Incisors

In order to investigate enamel and dentin phospholipid metabolic pathways, two separate experiments were carried out. Firstly, rats were given chloroquine, a drug which induces a lipidosis-like disease. Extensive accumulation inside lysosomes was seen in all the groups of cells in the forming part of the rat incisor, except secretory ameloblasts which were unaffected by the drug. Secondly, the uptake and fate of 3H-choline were studied by radioautography on rats fed either normally or on an essential fatty acid deficient diet (EFAD). Four hours after the injection of the precursor, incorporation reached a maximum then decreased gradually. At 4 days the forming enamel displayed higher silver grain density than any other compartment. In EFAD rats 3H-choline incorporation was decreased drastically in each compartment except in the forming enamel which was not affected by the deficiency. The longer retention of the labeling in the forming enamel and the lack of lysosomal accumulation in chloroquine-treated secretory ameloblasts support the hypothesis that fragments of the distal Tomes' process are released during enamel formation. Disconnected from the cells, membrane remnants are neither reinternalized nor subjected to further degradation inside lysosomes.

Fish oil inhibits Δ6 desaturase activity in vivo: Utility in a dietary paradigm to obtain mice depleted of arachidonic acid

In mice that were alternately fasted and then refed an essential fatty acid-deficient (EFAD) diet, there was a rapid and substantial decline in tissue n-3 and n-6 polyunsaturated fatty acids (PUFAs) and a corresponding increase in n-9 fatty acids. Combined in vivo activities of Δ6 + Δ5 desaturases were quantified directly by measuring the conversion of 14C-linoleic acid (intraperitoneal injection) to 14C-arachidonic acid in liver lipids. Δ5 desaturase activity was quantified by measuring the conversion of 14C-dihomo-γ-linolenic acid (intraperitoneal injection) to 14C-arachidonic acid in liver lipids. The combined Δ6 + Δ5 desaturase activities in EFAD mice was very similar to that in chow-fed control mice (35% vs. 33% conversion of 14C-linoleic acid to 14C-arachidonic acid, respectively). Subsequent refeeding of EFAD mice with an EFAD diet supplemented with corn oil restored tissue n-6 PUFA levels, but did not alter Δ6 + Δ5 desaturase activities (33%). In contrast, subsequent refeeding of EFAD mice with a fish oil-supplemented diet markedly inhibited Δ6 + Δ5 desaturase activities (7%). Fatty acid analysis of the livers from the fish oil-fed mice showed that there was a depletion of the n-6 PUFAs, linoleic acid, and arachidonic acid, and an increase in the n-3 PUFAs, eicosapentaenoic acid (20:5 n-3) and docosahexaenoic acid (22:6 n-3). The inhibition of Δ6 + Δ5 desaturase activities was also maintained in EFAD mice fed a 1:1 mixture of fish oil:corn oil. As a consequence, a unique fatty acid composition in liver and plasma was obtained in which arachidonic acid was selectively depleted, whereas linoleic acid and n-3 PUFAs were increased. Δ5 desaturase activity was not affected by any of the fasting/refeeding paradigms. The data demonstrate that dietary n-3 PUFAs negatively regulate the in vivo synthesis of n-6 PUFAs at the level of the Δ6 desaturase. The inhibition of Δ6 desaturase activity by n-3 PUFAs provides a basis for a unique dietary route to selectively reduce tissue arachidonic acid, while providing sufficient linoleic acid, an essential fatty acid, to support normal cellular metabolism. This dietary paradigm may be effective in attenuating diseases characterized by excessive production of arachidonic acid-derived eicosanoids.

Fatty acid composition, eicosanoid production and permeability in skin tissues of rainbow trout ( Oncorhynchus mykiss) fed a control or an essential fatty acid deficient diet

Rainbow trout ( Oncorhynchus mykiss) were fed either a control diet containing fish oil or an essential fatty acid (EFA) deficient diet containing only hydrogenated coconut oil and palmitic acid as lipid source (93.4% saturated fatty acids) for 14 weeks and the fatty acid compositions of individual phospholipid classes from skin and opercular membrane (OM) determined. The permeability of skin and OM to water and the production of eicosanoids in skin and gills challenged with the Ca 2+ ionophore A23187 were also measured. Phospholipid (PL) fatty acid compositions were substantially modified in EFA-deficient fish, with increased saturated fatty acids and decreased polyunsaturated fatty acids (PUFA), especially arachidonic acid (AA) and eicosapentaenoic acid (EPA), while docosahexaenoic acid (DHA) was largely retained. The onset of EFA deficiency was shown by the appearance of n-9 PUFA, particularly 20:3n-9. The main effects of EFA deficiency on phosphatidylcholine (PC) and phosphatidylethanolamine (PE) were to increase saturated fatty acids and monoenes, especially 16:1 and 18:1, and to decrease EPA and DHA. The content of DHA in phosphatidylserine (PS) was high in control animals (40% in skin and 35% in opercular membrane) and was mostly retained in EFA deficient animals. Arachidonic acid (AA) was the most abundant PUFA esterified to phosphatidylinositol (PI) and was significantly reduced in EFA deficient animals (from 31% to 13% in skin), where a large amount of 20:3n-9 (9% in skin) was also present. Influxes and effluxes of water through skin and opercular membrane were measured in vitro. No differences were detected between rainbow trout fed the control or the EFA deficient diet. 12-Hydroxyeicosatetraenoic acid (12-HETE), 12-hydroxyeicosapentaenoic acid (12-HEPE) and 14-hydroxydocosahexaenoic acid (14-HDHE) could not be detected in skin from control or EFA deficient fish. There was no difference between control and EFA deficient trout in the levels of leukotriene C 4 (LTC 4) and leukotriene C 5 (LTC 5) in skin cells challenged with the calcium ionophore A23187, and of prostaglandin F 2α (PGF 2α), 12-HETE and 12-HEPE in gill cells challenged similarly. Prostaglandin F 3α (PGF 3α) production by ionophore stimulated gill cells was significantly reduced in fish fed the EFA-deficient diet. 14-HDHE produced by gill cells was 3.3 fold higher in EFA deficient fish compared to controls.

Effects of essential fatty acid deficiency on prostaglandin E2 production and cell-mediated immunity in a mouse model of leprosy.

Results from animal and in vitro studies suggest that essential fatty acid (EFA) deficiency enhances cell-mediated immunity by reducing production of prostaglandins with immunosuppressive actions. However, direct experimental evidence that EFA deficiency enhances T-lymphocyte function in vivo has not been obtained. In this study, athymic (nu/nu) mice were infected in the footpads with Mycobacterium leprae and fed a linoleic acid-free diet. These mice, and infected nu/nu mice on control diets, were given an adoptive transfer of M. leprae-primed, T-cell-enriched lymphocytes. After 2 weeks, M. leprae bacilli were harvested from the recipient mice and bacterial viability was determined by the BACTEC system. M. leprae recovered from recipient mice fed control diets displayed little reduction in metabolic activity. In contrast, M. leprae from recipient mice fed the EFA-deficient (EFAD) diet exhibited markedly reduced viability. In vitro, donor cells from M. leprae-primed mice secreted elevated levels of gamma interferon upon exposure to the bacilli. These cells also exhibited an enhanced proliferative response, which was reduced by exogenous prostaglandin E2 (PGE2). In addition, M. leprae-infected granuloma macrophages (Mphi) from EFAD recipient nu/nu mice secreted significantly less PGE2 than granuloma Mphi from mice on control diets. These data suggest that enhanced levels of Mphi-generated PGE2, induced by M. leprae or its constituents, could act as an endogenous negative modulator of the immune response occurring in the microenvironment of the lepromatous granuloma.

Dietary deficiency or enrichment of essential fatty acids modulates tumorigenesis in the whole body of cobalt-60-irradiated mice

The effect of dietary polyunsaturated fatty acids (PUFAs) on whole body-induced tumorigenesis was assayed in mice fed on essential fatty acid sufficient (EFAS) or essential fatty acid deficient (EFAD) diets following cobalt-60 irradiation. Four groups of mice were maintained, one on a control stock diet and three on experimental diets: a) without added fat (fat free, FF); b) containing 5% olein (O), rich in n-9; and c) containing 5% corn oil, rich in n-6 EFA (CO). Only mice fed on FF or O diets showed clinical and biochemical signs of EFAD. Total incidence of tumors showed an increase in FF ( P < 0.02) and O ( P < 0.03) mice. Tumors developed mostly in the liver in each of the EFAD groups ( P < 0.001). Slight promoting activity on lung tumorigenesis was recorded in the CO group when this parameter was compared in EFAD and EFA sufficient mice. It may be concluded that, when a tumor initiator injures the body as a whole, EFAD, achieved either through a fat-free or an oleic-supplemented diet, behaves as a general promoting condition for tumorigenesis. The borderline tumorigenic effect of n-6 corn oil on the lungs suggests that this effect, when present, is target specific.

Epidermal injury stimulates prenylation in the epidermis of hairless mice.

Isoprenylation is the covalent attachment of isoprenyl groups, intermediates of the cholesterol biosynthesis pathway, to carboxyl terminal cysteine residues of proteins. Numerous proteins are isoprenylated including small GTP binding proteins, trimeric G proteins, and nuclear lamins, and these prenylated proteins regulate a variety of cell functions, including cell growth, cytokinesis, and differentiation. Here, we quantitated protein prenylation and determined which proteins are prenylated in the epidermis of hairless mice by radiolabeling with 3H-mevalonolactone following acute or chronic epidermal injury. In normal epidermis, four major radiolabeled bands, with molecular weights of 17-26, 48, 54, and 68 kDa, were observed. The levels of each of these bands increased by 24-63% 16 h following acute epidermal injury induced by topical acetone treatment or tape stripping, returning to normal by 24 h. On 2D gel electrophoresis, there were no major differences between the patterns of labeling following barrier disruption. Subacute epidermal injury induced by either acetone or tape stripping twice a day for 7 days and chronic injury induced by feeding an essential fatty acid-deficient (EFAD) diet, also resulted in a significant increase in protein prenylation. As with an acute injury, SDS-PAGE and 2D gel electrophoresis did not reveal marked differences in the pattern of protein prenylation. These results demonstrate that the prenylation of proteins in the epidermis is stimulated by injury, suggesting that one or more of these prenylated species may be important in epidermal proliferation or differentiation.

Peroxisomes and Essential Fatty Acid Deficiency.

The effect of dietary essential fatty acid (EFA) deficiency on the lipid composition of peroxisomal extracts was studied in Wistar rats. After 21 days of EFA deficiency, no difference was noted in protein levels, but a significant change had occurred in the level of phospholipids and fatty acid composition of phospholipids. In EFA-deficient rat peroxisomes, phosphatidylcholine and phosphatidylinositol were both significantly higher than in controls. This alteration was more marked in peroxisomes than in microsomes. The peroxisomal fatty acid composition was markedly affected as well. In EFA-deficient rats, linoleic (18:2 n-6), arachidonic (C20:4 n-6), and docosahexaenoic (C22:6 n-3) acids were lower whereas oleic (C18:1 n-9), octadecenoic (C18:1 n-7), and eicosatrienoic (C20:3 n-9) acids were higher than in controls. This alteration was also more prominent in the peroxisomal than the microsomal extracts. Catalase activity was weakly reduced, whereas dihydroxyacetone-phosphate acyltransferase activity was strongly increased in EFA-deficient rats. We conclude that the composition of phospholipids and fatty acids may be a factor contributing to peroxisome function and that a diet poor in essential fatty acids or defective unsaturated fatty acid metabolism could amplify peroxisomal dysfunction of genetic origin.

Dietary Essential Fatty Acid Deficiency Differentially Affects Tissues of Rats

Quantitative variations of polyunsaturated fatty acids (PUFA) were studied in various tissues: red blood cells (RBC), hepatic microsomes, kidney, skeletal muscle and heart of young rats fed either a control diet (n = 7) or an essential fatty acid (EFA)-deficient diet (n = 7). After 4 wk, the EFA-[deficient rats had significantly lower proportions of (n-6) and (n-3) fatty acids in RBC, hepatic microsomes and kidney than the control group. Paradoxically, normal proportions of arachidonic acid [20:4(n-6)] and 5,8,11,14,17-eicosapentaenoic acid [20:5(n-3)] were retained in heart and skeletal muscle despite generally lower proportions of the precursors, 18:2(n-6) and 18:3(n-3). Morever, absolute levels of 20:4(n-6) and 20:5(n-3) in skeletal muscle of the EFA deficient group were significantly higher than in controls and 22:5(n-3) and 22:6(n-3) levels were comparable. This suggests that fatty acid proportions alone, without any consideration of long-chain polyunsaturated fatty acid quantities, may not reflect the (n-6) and (n-3) PUFA status of individual tissues. This study indicates that diet-[induced changes in the PUFA composition of RBC, which are often used in clinical investigations, do not fully reflect the changes in the fatty acid composition of organs, and that individual tissues respond differently to EFA deficiency. The conservation of proportional and absolute levels of 20:5(n-3) and 20:4(n-6), and the decrease in the more unsaturated homologues in the heart, suggest that this organ may avidly retain 20:5(n-3) and 20:4(n-6) in order to maintain eicosanoid production.

Deficit of didocosahexaenoyl phospholipid in the eyes of larval sea bass fed an essential fatty acid deficient diet

Deficit of didocosahexaenoyl phospholipid in the eyes of larval sea bass fed an essential fatty acid deficient diet

Deficit of didocosahexaenoyl phospholipid in the eyes of larval sea bass fed an essential fatty acid deficient diet

Larval sea bass Dicentrarchus labrax of 27 days old were reared on Artemia enriched with Super Selco©, Tuna Orbital Oil or Yeast. The first diet is commonly used in mariculture for larval rearing, the second diet was designed to deliver an optimal docosahexaenoic acid (22: 6n‐3) to eicosapentaenoic acid (20: 5n‐3) ratio, and the third diet was deficient in docosahexaenoic acid (22: 6n‐3). The eyes of these larvae were analysed after 28 days and the molecular species of the three main phospholipid classes, phosphatidylcholine (PC), phosphatidylethanolamine (PE) and phosphatidylserine (PS) determined. Eyes from larvae fed Artemia enriched with yeast showed large decreases in molecular species containing 22: 6n‐3 compared to those supplemented with tuna orbital oil, most notably in 16: 0/22: 6n‐3 PC which fell from 10.6 to 0.4%, in 22: 6n‐3/22: 6n‐3 and 18: 1/22: 6n‐3 PE which fell from 29.6 to 0.3% and from 10.8 to 1.1% respectively, and in 22: 6n‐3/22: 6n‐3 PS which fell from 34.3 to 1.7%. Molecular species containing all other fatty acids, and especially 20: 5n‐3, were elevated in eyes from the yeast‐supplemented fish. In larvae fed Artemia enriched with Super Selco, amounts of eye 22: 6n‐3/22: 6n‐3 phospholipid were slightly lower in all three phospholipid classes compared to eyes from the tuna orbital oil‐supplemented larvae. There was also a trend of decreased saturated fatty acid/22: 6n‐3 and monounsaturated fatty acid/22: 6n‐3 molecular species in all classes from the Super Selco‐supplemented fish, the deficits being made up with molecular species containing 20: 5n‐3 and 22: 5n‐3. These results are discussed in relation to larval viability with particular respect to visual function.