Intussusception in the Syrian golden hamster

Of a series of ninety-six young male Syrian Golden hamsters, 13% developed lethargy, anorexia, diarrhoea and colocolic intussusception when their diet was changed from a basal laboratory-grade rodent chow to a nutritionally complete semi-purified diet. Histologically, the colon of the hamsters with intussusception had markedly reduced mucus production. Plasma levels of gastric inhibitory polypeptide (GIP) were reduced 80% (P less than 0.01) but peptide tyrosine/tyrosine and enteroglucagon in plasma were increased 290 and 526% respectively in hamsters with intussusception. Variations in dietary fatty acid composition had no effect but intussusception was not observed after changing the dietary carbohydrate from sucrose to starch.

Nibbling versus gorging: metabolic advantages of increased meal frequency

We studied the effect of increasing the frequency of meals on serum lipid concentrations and carbohydrate tolerance in normal subjects. Seven men were assigned in random order to two metabolically identical diets. One diet consisted of 17 snacks per day (the nibbling diet), and the other of three meals per day (the three-meal diet); each diet was followed for two weeks. As compared with the three-meal diet, the nibbling diet reduced fasting serum concentrations of total cholesterol, low-density lipoprotein cholesterol, and apolipoprotein B by a mean (+/- SE) of 8.5 +/- 2.5 percent (P less than 0.02), 13.5 +/- 3.4 percent (P less than 0.01), and 15.1 +/- 5.7 percent (P less than 0.05), respectively. Although the mean blood glucose level and serum concentrations of free fatty acids, 3-hydroxybutyrate, and triglyceride were similar during both diets, during the nibbling diet the mean serum insulin level decreased by 27.9 +/- 6.3 percent (P less than 0.01) and the mean 24-hour urinary C-peptide output decreased by 20.2 +/- 5.6 percent (P less than 0.02). In addition, the mean 24-hour urinary cortisol excretion was lower by 17.3 +/- 5.9 percent (P less than 0.05) at the end of the nibbling diet than at the end of the three-meal diet. The blood glucose, serum insulin, and C-peptide responses to a standardized breakfast and the results of an intravenous glucose-tolerance test conducted at the end of each diet were similar. We conclude that in addition to the amount and type of food eaten, the frequency of meals may be an important determinant of fasting serum lipid levels, possibly in relation to changes in insulin secretion.

Essential fatty acid and lipid profiles in plasma and erythrocytes in patients with multiple sclerosis

This study was conducted to investigate the possible differences in erythrocyte lipid composition, which might account for the previously reported increase in erythrocyte membrane zinc levels in patients with multiple sclerosis (MS). Compared with healthy control subjects, plasma lipids in patients with MS contained less sphingomyelin but more phosphatidylserine and the cholesterol-phospholipid ratio was 42% higher in the plasma from MS patients (p less than 0.01). In erythrocytes from MS patients, phosphatidylinositol was lower and erythrocyte cholesterol per milligram protein was significantly lower than concentrations in healthy control subjects (p less than 0.01). Among the long-chain fatty acids, the omega-3 fatty acids were lower in plasma from MS patients and linoleic acid was lower in erythrocyte ghosts from MS patients (p less than 0.01). We conclude that altered levels of cholesterol in plasma and erythrocytes from MS patients may contribute to increased erythrocyte-membrane Zn in MS patients. It cannot be stated with certainty whether the altered fatty acid profiles in MS patients were a function of the disease or of altered fatty acid intake.

Dietary carbohydrate influences tissue fatty acid and lipid composition in the copper-deficient rat

Fructose and copper have been shown independently to influence long chain fatty acid metabolism. Since fructose feeding exacerbates copper deficiency, their possible interaction with respect to tissue long chain fatty acid and lipid composition was studied. Weanling male Sprague-Dawley rats were given diets containing 0.6 or 6 mg/kg copper. The carbohydrate source (627 g/kg) was either fructose or corn starch. After 3 wk, fatty acid profiles and total lipids in heart and liver were analyzed. Copper-deficient rats fed fructose had more severe signs of copper deficiency than those fed starch, according to heart/body wt ratio, hematocrit, and liver copper content. The fatty acid composition of heart and liver triacylglycerol was significantly different between groups, but the changes did not correlate with the severity of copper deficiency. In heart, phosphatidylinositol and phosphatidylserine, arachidonic acid and docosapentaenoic acid (n-6) were increased 193 and 217%, respectively, p less than 0.05) in rats given the copper-deficient diet containing fructose. Changes in the long chain fatty acids in heart phospholipids may be related to the higher mortality commonly observed in rats fed a copper-deficient diet containing fructose.

Modulation of long chain fatty acid unsaturation by dietary copper

Research over the past 20 years into the effect of copper on fatty acid profiles in several species suggests that copper has a unique effect on long chain fatty acid metabolism. Copper supplementation in the pig and rat and copper deficiency in the rat, mouse and human indicates that inadequate copper intake (or genetic copper deficiency in the brindled mouse and in Menke's disease) impairs the ability to monounsaturate long chain saturated fatty acids and that, conversely, copper supplementation (greater than 150 mg/kg diet) usually increases monounsaturated fatty acids. Several recent studies of copper deficiency in the rat suggest that our interpretation of these effects needs to be more refined since membrane fatty acid profiles do not appear as sensitive to the effects of copper depletion as triglyceride fatty acid profiles. This suggests that changes in long chain fatty acid metabolism other than desaturation may also be affected by copper.

The profile of long-chain fatty acids in serum phospholipids: a possible indicator of copper status in humans

In previous reports of experimental copper depletion in humans, it was difficult to reliably demonstrate biochemically that there was Cu depletion. In view of the changes in serum phospholipid fatty acid profiles in Cu-deficient rats, it was considered worthwhile to determine the effect of Cu depletion in humans on serum fatty acid profiles. Serum samples from the Cu-depletion study of Reiser et al were analyzed for phospholipid fatty acid composition. After the participants had been on the low copper diet for 11 wk, serum phospholipids contained 27% less oleic acid, 38% more arachidonic acid, and 94% more docosahexaenoic acid (all p less than 0.01) than samples taken from the same subjects before Cu depletion. These fatty acid changes were of a similar direction and magnitude to those in moderately Cu-depleted rats and may be useful as an index of moderate Cu depletion in humans.

Copper intake affects rat heart performance during ischemia-reperfusion: possible relation to altered lipid and fatty acid metabolism

Hearts from rats fed low copper (1.3 mg copper/kg diet) or a copper-supplemented diet (243 mg copper/kg diet) were perfused for 90 min according to the Langendorff method. The perfusion protocol included 30 min normoxia, 30 min ischemia and 30 min reperfusion. After 90 min perfusion, hearts from the low copper group had gained more weight, had lower coronary perfusion pressure, developed less force of contraction and secreted less 6-keto PGF1 alpha into the perfusate than hearts from the copper-supplemented group. After perfusion, the major lipid change in the hearts from both groups was a 85-90% decrease in total triacylglycerol. In both groups, stearic acid and arachidonic acid (mg%) were increased in the triacylglycerol fraction after heart perfusion. The quantitative (mg/g) decrease in the triacylglycerol content of stearic acid and arachidonic acid was significantly less in the copper-supplemented group. After perfusion, dihomo-gamma-linolenic acid (mg/g) was lower in heart phospholipids from the low copper group. Dihomo-gamma-linolenic/arachidonic acid (microgram/mg) was significantly decreased after perfusion only in the hearts from the low copper group. Lipid and fatty acid changes in the hearts of the rats fed low dietary copper may contribute to abnormal heart function in this group.

Effects of low magnesium diet on the vascular prostaglandin and fatty acid metabolism in rats

Deficiency of magnesium with cardiovascular effects is thought to be related to alterations in the biosynthesis of prostaglandins (PGs) in the vasculature. Measurements were made of the PGE2, 6-keto-PGF1 alpha and thromboxane B2 (TxB2) outflow from the perfused isolated mesenteric arterial bed and the fatty acid composition of the tissue in rats maintained for 14 weeks on a low magnesium (LMg) diet. The serum Mg levels were significantly decreased and the serum Ca levels were significantly increased in the LMg group as compared to the controls. The arachidonic acid concentration in the triacylglyceride fraction was significantly increased in the LMg group. Long chain polyunsaturates such as 22:4n6 and 22:6n3 were consistently increased in the LMg rats as compared to the controls in both the phospholipid and triglyceride fractions as previously reported in other tissues. The PGE2, 6-keto-PGF1 alpha and TxB2 outflows were significantly increased in the LMg group as compared to the controls. These findings suggest that the biosynthesis of eicosanoids, mainly PGI2, is stimulated in Mg deficiency, and this may provide protection against intracellular Mg depletion and Ca accumulation, so as to counteract to the constricted and hyperreactive state of the vasculature in such a condition.

Differential utilization of long chain fatty acids during triacylglycerol depletion. II. Rat liver after starvation

Rats starved for 96 hr were shown to have a 94% reduction in liver triacylglycerol. Among the long chain fatty acids in liver triacylglycerol, only stearic acid and arachidonic acid were proportionally increased (2.5 and 6 times, respectively); palmitic and linoleic acids were unchanged, and palmitoleic and oleic acids were proportionally decreased. Stearic and arachidonic acids (mg%) were correlated positively within the triacylglycerol fraction, and both fatty acids varied inversely with total triacylglycerol (mg/g) in fed and starved rats. The utilization of long chain fatty acids from liver triacylglycerol during starvation resulted in selective retention of arachidonic acid and stearic acid and suggests that differential hydrolysis of liver triacylglycerol by hepatic lipase may occur or selective reacylation of these specific fatty acids may occur during starvation.

Evidence that adverse effects of zinc deficiency on essential fatty acid composition in rats are independent of food intake

1. Young male rats were fed on diets containing 3.4, 36 or 411 mg zinc/kg for 10 weeks in order to determine whether effects of Zn deficiency on plasma and liver essential fatty acid composition could be distinguished from those of reduced protein and energy intake. 2. Fatty acid analysis revealed that a Zn intake of 3.4 mg/kg (plasma Zn 0.80 v. 1.97 mmol/l in controls fed on 36 mg Zn/kg) resulted in a significant increase in the linoleic acid:arachidonic acid ratio in both plasma and liver phospholipids in comparison with rats fed on 36 or 411 mg Zn/kg. 3. Zn supplementation (411 mg/kg) decreased the linoleic acid:arachidonic acid ratio in plasma phosphatidylserine compared with that of the controls. 4. The previously reported increase in arachidonic acid (mol %) in liver triacylglycerol of Zn-deficient rats was shown to be a function of a reduced liver triacylglycerol pool size; quantitatively, triacylglycerol content of arachidonic acid in the liver was not significantly affected by Zn intake.

Vitamin E intake affects serum thromboxane and tissue essential fatty acid composition in the rat

The influence of dietary vitamin E on the composition of essential fatty acids in rat tissue and plasma lipids as well as serum thromboxane B2 was studied. Diets containing deficient (0 mg/kg diet), adequate (100 mg/kg) or supplemental (1,000 mg/kg) vitamin E were fed to young male rats for 10 weeks. The ratio of dihomo-gamma-linolenic acid to arachidonic acid in phospholipids of plasma, liver, and testes was increased in vitamin-E-supplemented rats. Serum thromboxane B2 was increased in vitamin-E-deficient rats. The data support a role for vitamin E in affecting both metabolism of long chain fatty acids, i.e. dihomo-gamma-linolenic acid, and conversion of arachidonic acid to thromboxane A2.

Differential utilization of long chain fatty acids during triacylglycerol depletion. I. Rat heart after ischemic perfusion

Rat hearts were perfused with Krebs-Henseleit buffer for 90 min according to the Langendorff procedure. Normoxic perfusion for 90 min resulted in minor changes in fatty acid composition and a decrease in residual heart triacylglycerol to 60% of preperfusion values. When the protocol included 30 min of slow perfusion-induced ischemia, the hearts were observed to be depleted of 89% of their initial triacylglycerol content. The triacylglycerol fatty acid composition (mg %) remained similar after compared to before perfusion except for a 121 mg % increase in stearic acid and a 225 mg % increase in arachidonic acid. The percentage composition of both fatty acids was significantly inversely correlated with the amount of triacylglycerol remaining in the heart after perfusion. Postperfusion, arachidonic acid and stearic acids were present at nearly 1:1 in the residual heart triacylglycerol, suggesting that a common mechanism may be involved in the selective retention of these fatty acids by the heart.

Abnormalities of plasma and erythrocyte essential fatty acid composition in epidermolysis bullosa: influence of treatment with diphenylhydantoin

The fatty acid composition of plasma and erythrocyte phospholipids was determined in children with various subtypes of epidermolysis bullosa (EB) and in their parents. Patients with recessive dystrophic, dominant dystrophic, simplex, or junctional forms of EB had a higher percentage composition of arachidonic acid in plasma and/or erythrocyte phospholipids compared to age-matched controls. Epidermolysis bullosa patients treated with diphenylhydantoin had lower levels of arachidonic acid in plasma and erythrocyte phospholipids than did untreated EB patients. Parents of children with the recessive dystrophic or junctional EB subtypes had higher linoleic and arachidonic acids in plasma and erythrocyte phospholipids than did controls. Plasma and erythrocyte total lipids were within the normal range in children with EB. Plasma zinc was also normal but plasma copper was elevated in children with recessive dystrophic EB. We conclude that higher arachidonic acid in plasma and erythrocytes may be related to the pathology of EB.

Iron intake influences essential fatty acid and lipid composition of rat plasma and erythrocytes

In view of the clinical importance of iron deficiency as well as the known role of iron in stearic acid desaturation, the effects of higher or lower iron intake on fatty acid composition of blood and liver in the rat were studied. Male Sprague-Dawley rats were fed purified diets that contained iron at 12, 27 or 237 mg/kg. After 12 wk the lipid and fatty acid composition of plasma, erythrocytes and liver was analyzed. Linoleic acid in plasma phospholipids and triacylglycerols was higher, but arachidonic acid was lower in the group fed 12 mg/kg iron than in the groups fed 27 or 237 mg/kg iron. Liver fatty acid and lipid composition was not different between groups. In the group fed 237 mg/kg iron, plasma cholesterol and triacylglycerols were 150%, erythrocyte cholesterol was 137% and erythrocyte phospholipids were 148% of levels in the rats fed 27 mg/kg iron. The fatty acid data suggest a mild impairment in essential fatty acid metabolism in moderately iron-deficient rats. The lipid data suggest a significant alteration in the total lipid content of plasma and erythrocytes of iron-supplemented rats.

Hepatic triacylglycerol accumulation induced by ethanol and carbon tetrachloride: interactions with essential fatty acids and prostaglandins

Triacylglycerol accumulation in the liver (fatty liver) caused by ethanol or carbon tetrachloride involves interactions with essential fatty acids and prostaglandins. The degree to which the fatty liver develops is dependent on total dietary fat intake. Both ethanol and carbon tetrachloride impair desaturation of linoleic acid and dihomo-gamma-linolenic acid and this appears to be relevant to the pathogenesis of fatty liver from two points of view. First, low arachidonic acid in liver phospholipids is associated with increased liver triacylglycerol content whether caused by ethanol, carbon tetrachloride, or essential fatty acid deficiency. Second, essential fatty acids including gamma-linolenic acid and arachidonic acid, as well as the prostaglandins, prevent ethanol- and carbon tetrachloride-induced fatty liver. Arachidonic acid and possibly the prostaglandins are therefore likely to be directly involved in lipoprotein and triacylglycerol secretion by the liver.

Long-term ethanol consumption in the hamster: effects on tissue lipids, fatty acids and erythrocyte hemolysis

Male Golden Syrian hamsters at 1 year of age were given a basal diet and either distilled water or 10% absolute ethanol in distilled water to drink for 1 year in order to determine the influence of prolonged ethanol intake on tissue long chain fatty acid, lipid composition and erythrocyte hemolysis in response to osmotic stress. Total lipids were extracted from liver, heart, plasma and erythrocytes. Individual lipid fractions were quantitated and the percentage fatty acid composition of the lipid fractions analyzed by gas-liquid chromatography. Although no significant changes in tissue lipid content or erythrocyte hemolysis were attributable to ethanol intake, fatty acid changes were marked in the ethanol-fed hamsters. The primary fatty acid changes were increased oleic acid (40-50%) and decreased linoleic acid (25-60%) which were observed in all tissues. Arachidonic acid was decreased only in triacylglycerol fractions. The results suggest that in the hamster long-term voluntary ethanol intake alters specific long chain fatty acids, but that erythrocyte membrane integrity and tissue lipid composition were not compromised.

Dietary manipulation of ethanol preference in the Syrian golden hamster

Male Golden Syrian hamsters, in which ethanol preference was previously established, were fed a basal diet supplemented with essential fatty acid-rich oils (increased weekly from 10-160 g/kg diet), cholesterol (10 g/kg diet) or retinol palmitate (100 or 200 mg/kg diet), each in an independent study. Within 4-5 weeks, all three supplements were associated with significantly decreased ethanol preference. No consistent change in the fatty acid composition of liver or brain was associated with the decrease in ethanol preference but, in ethanol-fed hamsters, each of the supplements was associated with an increase in total cholesterol and the cholesterol/phospholipid ratio in liver. The essential fatty acid-induced reduction in ethanol preference was not associated with a significant change in blood ethanol elimination rate or time.

Lipid and fatty acid composition of organs from copper-deficient mice

Experiments were conducted to study the total lipid and fatty acid composition of liver, kidney, brain and heart of 7-wk-old male C57BL mice. Dietary copper deficiency was initiated at birth by feeding dams a purified diet containing 0.5 mg/kg copper. Offspring were fed the copper-deficient diet 4 wk postweaning. Control dams and offspring were fed the same diet but with added copper in the drinking water, 20 mg/L. Compared with controls the copper-deficient mice exhibited hepatomegaly, cardiac hypertrophy and a 4% reduction in brain weight as well as low ceruloplasmin activity (0.5% of control). Total phospholipid concentration in liver and kidney and total triacylglycerol concentration in kidney was lower in copper-deficient mice compared to concentrations measured in liver and kidney of control mice. The major change in essential fatty acid composition in the copper-deficient mice which was consistent between organs and lipid classes was a significantly lower proportion and absolute amount of dihomo-gamma-linolenic acid. Other changes in fatty acid composition were variable.

n-3 Essential fatty acids decrease weight gain in genetically obese mice

1. Lean (ln/ln) and obese (ob/ob) mice were given diets containing a fat source of 100 g evening primrose (Oenothera biennis) oil (fatty acids 18:2n-6, 18:3n-6; EPO) or 100 g cod liver oil (20:5n-3, 22:6n-3; CLO)/kg diet. 2. Weight gain was lower in the ob/ob mice fed on CLO, an effect unrelated to food intake. 3. In the ob/ob mice fed on CLO, thromboxane synthesis by clotting platelets was reduced compared with that in ob/ob mice fed on EPO. 4. The ob/ob CLO-fed mice had lower arachidonic acid but higher levels of n-3 fatty acids in liver, brown adipose tissue and white adipose tissue. 5. The n-3 fatty acids in CLO therefore replaced the n-6 fatty acids in tissue lipids and reduced synthesis of '2 series' prostaglandins in addition to causing lower weight gain in the CLO-fed ob/ob mice.

Transient neonatal zinc deficiency

We report an infant who developed clinical manifestations of zinc deficiency during the first month of life although the diet was adequate for zinc and no other causes could be ascertained. The diagnosis was confirmed by low plasma-zinc concentrations and a positive response to zinc treatment. The fatty acid profile of plasma phospholipids was typical of zinc deficiency (ie, arachidonic acid was markedly decreased). The transient nature of this disorder was evident when no relapse occurred after cessation of zinc therapy and plasma-zinc and arachidonic acid concentrations remained normal. Several explanations for the development of transient neonatal zinc deficiency are offered. The observation demonstrates that occasional infants may have requirements for zinc that are beyond the intakes of the conventional RDA.

Triacylglycerol content of arachidonic acid varies inversely with total triacylglycerol in liver and plasma

In both liver and plasma from rats, hamsters, guinea pigs and monkeys, the correlation coefficients between percentage composition of arachidonic acid and the total triacylglycerol varied from -0.43 to -0.81 (P less than 0.01). No such relationship was present between percentage compositions of any of the essential fatty acids in phospholipids and total phospholipids.

Effect of different dietary proteins on plasma and liver fatty acid compositions in growing rats

Weanling male rats were fed semipurified diets containing 20% protein derived from casein, soy protein, or wheat gluten for 5 weeks. The fat source was 2% safflower oil (containing 79.4% 18:2n-6). In comparison with the casein-fed rats, the growth rate of rats fed plant proteins was slower, particularly that of rats fed the wheat gluten diet. The plasma cholesterol levels were significantly lower in rats fed wheat gluten than in those fed the other dietary protein regimens. The fatty acid compositions of plasma and liver lipids were also examined. The ratios of 16:1/16:0, 18:1/18:0 and 20:4n-6/18:2n-6 in both plasma and liver phospholipids and cholesteryl esters were consistently reduced in animals fed plant protein suggesting a reduced activity of fatty acid desaturation. The reduction of fatty acid desaturation may possibly be attributed to the low lysine/arginine ratio in plant proteins.