Influence of different dietary fatty acid sources on erythrocyte lipids and plasma and liver essential fatty acids in hamsters fed ethanol

Hamsters fed ethanol were given three different dietary sources of essential fatty acids; safflower oil, evening primrose oil (both mainly n-6 fatty acids) or linseed oil (mainly n-3 fatty acids). After 7 weeks, plasma, erythrocyte and liver lipids and fatty acids were analyzed. Plasma and liver lipids were not significantly different in the ethanol-fed hamsters compared to the controls. Erythrocyte total phospholipid was increased only in the ethanol-fed groups given n-6 but not n-3 fatty acids. Some fatty acid changes induced by ethanol were predictable, e.g. lower 20:4 n-6 in hamsters fed n-6 fatty acids, but others were not predictable, e.g. higher 22:6 n-3 in all the ethanol-fed groups. The effect of ethanol on hamster lipids and fatty acid composition appears dependent on the predominant class of dietary fatty acids.

Diminished phospholipid incorporation of essential fatty acids in peripheral blood leucocytes from patients with Crohn's disease: correlation with zinc depletion

Peripheral blood leucocytes from patients with Crohn's disease have been shown to have lower zinc content than those from a normal population. Since zinc influences essential fatty acid metabolism, incorporation of 14C-linoleic and 3H-arachidonic acids was studied in peripheral blood leucocytes from controls and patients with Crohn's disease. The zinc content of the leucocytes was also measured. After incubation for 2 h, content of 3H-arachidonic acid, but not 14C-linoleic acid, was greater in Crohn's disease leucocytes than in controls. In the Crohn's disease leucocytes, incorporation of both labelled fatty acids into the phosphatidylcholine fraction was significantly lower than in controls, whereas the amount of both fatty acids remaining in the leucocytes as free fatty acids was increased by 70%. In Crohn's disease, leucocyte zinc level was positively associated with the percentage of 3H-arachidonic acid incorporation into phosphatidylcholine. We conclude that peripheral blood leucocytes from patients with Crohn's disease have abnormal essential fatty acid metabolism and that 3H-arachidonic acid incorporation into the phosphatidylcholine fraction of leucocyte lipids in Crohn's disease varies as the zinc content of the leucocytes.

Magnesium deficiency in the rat increases tissue levels of docosahexaenoic acid

The effects of magnesium deficiency on tissue levels of total lipids and fatty acids were evaluated. Sprague-Dawley rats were fed a magnesium-deficient diet for 14 wk with controls being pair-fed to the deficient rats. Compared to the controls, serum and 24-h urinary magnesium levels were markedly lower in the magnesium-deficient rats. Serum cholesterol and total phospholipids were significantly higher in the magnesium-deficient rats than in the controls. Edema and polycystic degeneration of the kidneys were present in the magnesium-deficient rats. Kidney total phospholipids and triacylglycerols were significantly lower in the magnesium-deficient rats than in the controls. The main change in tissue fatty acid composition in magnesium deficiency was the higher docosahexaenoic acid (22:6n-3) in serum, liver and aorta than in controls. The possible relationship of these findings to human alcoholism is discussed.

Essential fatty acids in the liver and adipose tissue of genetically obese mice: effect of supplemental linoleic and gamma-linolenic acids

Genetically obese mice (ob/ob) and their lean litter-mates were given diets iso-energetically supplemented with sucrose, hydrogenated coconut oil, safflower oil or evening primrose (Oenothera biennis) oil. Weight gain over 15 weeks was significantly greater in the evening primrose oil-supplemented obese mice than in the other groups. In all the groups of obese mice, liver total phospholipids contained proportionally less linoleic acid and more dihomo-gamma-linolenic acid and arachidonic acid than did the lean controls. As a percentage of total fatty acids, n-3 essential fatty acids (EFA) in liver and adipose tissue lipids were significantly lower in the obese mice than in the lean controls. Supplementation with EFA-rich oils (safflower and evening primrose oil) increased the proportional composition of n-6 EFA and decreased the n-3 EFA more in the liver total phospholipids of the lean than the obese mice.

Abnormal essential fatty acid composition of tissue lipids in genetically diabetic mice is partially corrected by dietary linoleic and gamma-linolenic acids

Genetically diabetic mice (db/db) and their non-diabetic litter-mates were maintained for 15 weeks on diets supplemented with safflower oil or evening primrose (Oenothera bienis) oil, both essential fatty acid (EFA)-rich sources, or hydrogenated coconut oil (devoid of EFA). Plasma glucose was higher in the diabetic mice supplemented with the oils than in the unsupplemented diabetic mice. In the oil-supplemented non-diabetic mice, plasma glucose did not differ compared with the unsupplemented non-diabetic mice. The proportional content of arachidonic acid in the phospholipids of the pancreas was significantly decreased in diabetic mice, an effect which was completely prevented by supplementation with safflower or evening primrose oil but not hydrogenated coconut oil. In the liver phospholipids of the diabetic mice, dihomo-gamma-linolenic acid was proportionally increased, an effect reduced by supplementation with safflower oil but not evening primrose or hydrogenated coconut oils. In the liver triglycerides of the diabetic mice, gamma-linolenic acid, dihomo-gamma-linolenic acid and arachidonic acid were all proportionally decreased, effects which were also prevented by safflower or evening primrose oil but not hydrogenated coconut oil. Alopecia and dry scaly skin were prominent in the diabetic mice but less extensive in the diabetic mice supplemented with EFA.

Contrasting effects of low or high copper intake on rat tissue lipid essential fatty acid composition

The effects of low copper intake or copper supplementation on the metabolism of stearic acid have been studied previously, but their effects on essential fatty acids have not been reported. Male Sprague-Dawley rats were fed for 12 weeks on pelleted semi-synthetic diets containing less than 1 mg/kg copper (low copper), 6 mg/kg (copper control), or 250 mg/kg copper (copper supplemented). The fatty acid composition of the total phopholipids and triglycerides of plasma, liver, heart and adipose tissue was analyzed by gas liquid chromatography. In low copper rats compared to controls, palmitic and oleic acids were decreased but stearic acid and docosahexaenoic acid were increased in plasma, liver and heart phopholipids. Arachidonic acid was also increased in plasma and liver phospholipids in low copper rats. In liver triglycerides, linoleic and arachidonic acids were increased but palmitic and oleic acid were decreased in low copper rats. Copper supplementation had the opposite effect; palmitic and oleic acids were increased in phospholipids and triglycerides whereas essential fatty acids were generally decreased. Hence, copper not only has a direct effect on the desaturation of stearic acid but also has significant effects on the tissue lipid composition of essential fatty acids.

Effect of ethanol on liver triglycerides and fatty acid composition in the golden Syrian hamster

In choice situations, the golden Syrian hamster shows a strong preference to drink an ethanol solution to water alone. Because of the known effects of ethanol on lipid metabolism, its effects on liver fatty acids were therefore studied in the hamster. After a period of 8 weeks during which hamsters had consumed water containing 10% ethanol (4 weeks) and then 15% ethanol (4 weeks), the liver was significantly increased in weight, an effect which was shown to be due to fat accumulation as triglyceride. The fatty acid composition of the liver triglycerides and phospholipids was altered such that monounsaturated fatty acids were very significantly increased and both n-6 and n-3 essential fatty acids were proportionally decreased.

Essential fatty acids in tissue phospholipids and triglycerides of the zinc-deficient rat

This study addressed the possibility that zinc deficiency has different effects on the fatty acid composition of triglyceride compared to total phospholipid. Male weanling Sprague-Dawley rats were maintained for 6 weeks on a semisynthetic diet deficient in zinc (3 mg/kg zinc). Control rats (40 mg/kg zinc) were pair-fed. Lipid fractionation and fatty acid analysis were by thin-layer and gas chromatography, respectively. In zinc-deficient rats, the percentage of linoleic acid was increased or that of arachidonic acid was decreased in total phospholipids of plasma, liver, and testis, and in skin total lipids. Saturated and monounsaturated fatty acids were increased in the triglyceride of liver but decreased in the triglyceride of epididymal fat of zinc deficient rats. Essential fatty acids, as a proportion of total fatty acids, were decreased in triglyceride of liver but increased in triglyceride of epididymal fat of zinc-deficient rats. Our fatty acid data from tissue total phospholipids therefore support the concept that linoleic acid desaturation is impaired in zinc deficiency.

Essential fatty acids in plasma, red blood cells and liver phospholipids in common laboratory animals as compared to humans

Essential fatty acids were estimated in plasma, red blood cells and liver total phospholipids in rats, mice, hamsters, guinea pigs, rabbits and humans. There were large species differences, suggesting that different species levels should be borne in mind when choosing an animal for a particular study. The 2 species most susceptible to atheroma, the guinea pig and the rabbit, had very high levels of linoleic acid and low levels of linoleic acid metabolites. n-3 fatty acid levels were low in guinea pigs and rabbits and the ratio of n-3 to n-6 fatty acids also was low in the rat. Mice and hamsters had the highest n-3 levels, suggesting they may be the best species to use for studies on the roles of n-3 essential fatty acids. Mice and hamsters and, in some respect rats, were closest to humans in their fatty acid patterns.

Accumulation of linoleic and gamma-linolenic acids in tissue lipids of pyridoxine-deficient rats

Young male Sprague-Dawley rats were fed diets containing added pyridoxine . HCl at 22 mg/kg (control), 0 mg/kg or 88 mg/kg for 6 weeks. In comparison with control or pyridoxine-supplemented (+PN) rats, growth of the pyridoxine-deficient (-PN) rats was significantly less after 2 weeks. After 6 weeks, liver weight was higher but thymus and epididymal fat weights, in relation to body weight, were significantly lower in -PN compared to control rats. In -PN rats, phospholipid levels of linoleic and gamma-linolenic acids were increased, but arachidonic acid was decreased compared to controls in plasma, liver, thymus and skin. In liver triglycerides from -PN rats, all essential fatty acids (n3 and n6) were increased compared to both control and +PN rats. The n3 essential fatty acids were significantly increased in plasma, liver, and thymus phospholipids in the +PN compared to control rats. These results support previous reports of an effect of pyridoxine on essential fatty acid metabolism and suggest that both linoleic desaturation and gamma-linolenic acid elongation may be impaired in -PN rats. In addition, the accumulation of essential fatty acids in the liver triglycerides of -PN rats suggests that essential fatty acid turnover between triglyceride and phospholipid may be influenced by pyridoxine.

Linoleic acid and arachidonic acid metabolism in human peripheral blood leucocytes: comparison with the rat

Peripheral blood leucocytes from human male volunteers and from male rats were incubated in vitro in the presence of 14C-labelled linoleic acid [( 14C]LA) or 3H-labelled arachidonic acid [( 3H]AA). The time-course of [14C]LA and [3H]AA incorporation into human leucocyte total lipids was maximal at 80-90% of the initial dose within 20-30 min of dosing the cells. Compared with mixed leucocytes, isolated polymorphonuclear leucocytes were only marginally different in the differential incorporation of [14C]LA and [3H]AA into total lipids. In human leucocytes, [14C]LA was incorporated initially into triglycerides but predominantly into phosphatidylcholine thereafter. In the rat, [14C]LA remained as the free acid (63%), with lesser amounts entering the phospholipids (9%), monoglycerides-diglycerides (12%) and triglycerides (less than 1%). Utilization of [14C]LA by the delta 6-desaturase was only a minor route of its metabolism in both human and rat leucocytes. 3H-labelled prostaglandins E2 and F2 alpha accounted for up to 30% of the radioactivity released into the incubation medium from human leucocytes incubated with [3H]AA for 60 min. Stimulation of phagocytosis in the human leucocytes with latex beads or with unopsonized zymosan did not alter the differential incorporation of [14C]LA or [3H]AA into the leucocyte lipid fractions.

Uteroplacental dysfunction and prostaglandin metabolism in zinc deficient pregnant rats

Relationships between perinatal mortality, disrupted utero-placental function and prostaglandin metabolism have been studied in Zn-deficient rats. Uterine contractility in vitro, placental blood flow in vivo, and uterine and placental prostaglandin synthesis from [1-14C] arachidonic acid in vitro were investigated at day 22 of pregnancy. High amplitude uterine contractions were almost completely eliminated and utero-placental blood flow was decreased by 85% by Zn deficiency. Synthesis of [1-14C]-prostaglandin E2, F2 alpha and 6-keto-F1 alpha from [1-14C] arachidonic acid decreased significantly in uterine tissue but increased in placentae. These possibly inter-related effects may contribute to the high perinatal mortality observed in Zn deficiency.

Maternal essential fatty acid supplementation increases zinc absorption in neonatal rats: relevance to the defect in zinc absorption in acrodermatitis enteropathica

Pregnant zinc deficient and zinc adequate rats were injected subcutaneously with evening primrose oil throughout gestation and for 3 days post partum. The nursing pups were injected intragastrically with zinc-65 on day 3 of live and sacrifices 4 h later. The % of the total injected zinc recovered in the carcass (minus the gut and gut contents) was significantly increased in those pups nursed by mothers injected with evening primrose oil, regardless of their dietary zinc intake. The fatty acid composition of the total lipid extract of the gut and gut contents of the neonates with increased zinc-65 absorption indicated that these pups had higher proportions of arachidonic acid and other metabolites of linoleic acid than did those with lower zinc-65 absorption. In other 3-day-old rat pups, intragastric injection of linoleic, gamma-linolenic or dihomo-gamma-linolenic acids along with the dose of zinc-65 very significantly increased zinc-65 absorption in a dose-related manner. Arachidonic acid however had no significant effect on zinc-65 absorption. Prostaglandin E1 caused a significant increase in zinc-65 absorption but prostaglandin E2 had no consistent effect. Indomethacin caused a dose-related inhibition of zinc-65 absorption.

Foetal mortality in moderately zinc-deficient rats is strictly related to the process of parturition: effect of maternal essential fatty acid supplementation

1. Although disrupted parturition and high foetal losses have previously been reported in pregnant rats maintained on zinc-deficient diets this is the first report to differentiate between the effects of reduced Zn intake and the effects of reduced food intake on the outcome of pregnancy in the rat. 2. Rats maintained on a 0.5 mg Zn/kg diet for the last 7 d of gestation or on a 5 mg Zn/kg diet throughout gestation did not consume significantly less food than rats given 10 or 20 mg Zn/kg diets except during the last 2d of gestation. Pair-feeding of Zn-adequate rats (20 mg/kg) to those given low-Zn diets for the last 2 d of gestation did not affect the outcome of pregnancy in these rats. 3. In the rats maintained throughout gestation on 5 mg Zn/kg or on 0.5 mg Zn/kg in the last 7 d of gestation, parturition onset and duration were not significantly altered. Foetal survival was very significantly reduced but only from day 22 onwards; before the onset of parturition, foetal survival was not significantly affected by Zn deficiency during gestation. 4. Subcutaneous injection of evening primrose (Oenothera biennis) oil into rats throughout gestation enhanced foetal and neonatal survival in rats given 5 mg Zn/kg but reduced foetal survival in rats given 0.5 mg Zn/kg in the last 7 d of gestation. 5. The results suggest three points: (1) subtotal Zn deficiency during gestation in the rat jeopardises foetal survival at parturition without affecting the onset or duration of parturition, (2) foetal death in rats maintained on Zn-deficient diets occurs only in relation to parturition itself, (3) provided that Zn intake near term is at least 5 mg/kg, supplemental essential fatty acids (evening primrose oil) will reduce foetal mortality during parturition and in the neonatal period.

Zinc deficiency increases the rate of delta 6 desaturation of linoleic acid in rat mammary tissue

The effect of zinc deficiency on the delta 6-desaturation of [1-14C]linoleic acid was studied in mammary tissue microsomes from lactating rats. The rats were maintained on zinc-adequate (20 ppm zinc) or zinc-deficient (10 ppm zinc changing to 0.5 ppm zinc during last trimester) diets throughout gestation and for the first 3 days of lactation. Mammary tissue microsomes were incubated with [1-14C]linoleic acid and other samples of mammary tissue, mammary milk and the milk in the stomachs of the pups were analyzed for total fatty acid composition. In mammary microsomes from zinc-deficient rats, delta 6-desaturation of linoleic acid was 3.4 times greater than in microsomes from zinc-adequate rats. This change in metabolism of linoleic acid was reflected by comparable changes in the relative tissue and milk composition of linoleic and arachidonic acids and in the ratios of palmitic to palmitoleic acid, stearic to oleic acid and linoleic and arachidonic acid.

The vascular response to zinc varies seasonally: effect of pinealectomy and melatonin

The effect of physiological concentrations of zinc on the in vitro pressor responses of male Wistar rat mesenteric preparations to norepinephrine was systematically studied over a 2-year period. A marked seasonal variation in the response of the preparations was observed over a range of zinc concentrations from 3.5 X 10(-11) to 3.5 X 10(-6) M. All concentrations of zinc inhibited pressor responses during the winter (November to March), but during the spring months (April to May) zinc became very much less effective and low concentrations of zinc potentiated the response. Inhibition of the pressor response at this time only occurred at zinc concentrations above 3.5 X 10(-7) M. In the summer months. (June to September) the zinc effect shifted back towards the winter situation with lower concentration of zinc potentiating and higher concentrations inhibiting vasoconstriction. Pinealectomy of the rats a week prior to preparation of the mesenteric beds very significantly enchanced pressor responses to norepinephrine in the winter months but had much less effect in the summer. The seasonal variation noted in preparations from control rats was maintained following pinealectomy but the amplitude was reduced. Perfusion of melatonin (4.3 X 10(-10) M through preparations from pinealectomized rats enhanced the inhibitory effect of zinc compared to the response to zinc from similarly perfused preparations from control rats. Thus, the rat mesenteric vascular bed is an in vitro model of seasonal variation in vascular reactivity which is sensitive to physiological concentrations of zinc. The origin of the seasonal rhythmicity remains speculative particularly in view of the fact that the rats were maintained under constant photoperiod. That the pineal may modulate the seasonal effect of zinc is suggested by the shift in response to zinc following pinealectomy. Melatonin reversed the effect of pinealectomy on this preparation implicating it as a possible mediator of normal vascular reactivity to zinc. A possible influence of magnetic radiation in evaluating the occurrence of seasonally varying phenomena in vitro should be considered.