Decrease of eicosapentaenoic acid in fatty liver of diabetic subjects

Lipoatrophy-Associated Insulin Resistance and Hepatic Steatosis are Attenuated by Intake of Diet Rich in Omega 3 Fatty Acids

SCOPE

Glucose homeostasis and progression of nonalcoholic fatty liver disease (NAFLD) and hepatomegaly in severe lipoatrophic mice and their modulation by intake of a diet rich in omega 3 (n-3) fatty acids (HFO) are evaluated.

METHODS AND RESULTS

Severe lipoatrophic mice induced by PPAR-γ deletion exclusively in adipocytes (A-PPARγ KO) and littermate controls (A-PPARγ WT) are evaluated for glucose homeostasis and liver mass, proteomics, lipidomics, inflammation, and fibrosis. Lipoatrophic mice are heavier than controls, severely glucose intolerant, and hyperinsulinemic, and develop NAFLD characterized by increased liver glycogen, triacylglycerol, and diacylglycerol contents, mitotic index, apoptosis, inflammation, steatosis score, fibrosis, and fatty acid synthase (FAS) content and activity. Lipoatrophic mice also display liver enrichment with monounsaturated in detriment of polyunsaturated fatty acids including n-3 fatty acids, and increased content of cardiolipin, a tetracyl phospholipid exclusively found at the mitochondria inner membrane. Administration of a high-fat diet rich in n-3 fatty acids (HFO) to lipoatrophic mice enriches liver with n-3 fatty acids, reduces hepatic steatosis, FAS content and activity, apoptosis, inflammation, and improves glucose homeostasis.

CONCLUSION

Diet enrichment with n-3 fatty acids improves glucose homeostasis and reduces liver steatosis and inflammation without affecting hepatomegaly in severe lipoatrophic mice.

Omega 3 - Omega 6: What is right for the liver?

Linoleic and alpha-linolenic acids are the fatty acids designated as "essential" since they are not synthesized by mammalian cells and must be provided in the diet. The recent dietary shift towards the consumption of n-6 (omega-6) at the expense of n-3 (omega-3) polyunsaturated fatty acids (PUFAs) is thought to be a primary cause of many diseases related to the Western diet. The body converts linoleic acid to arachidonic acid and derives eicosapentaenoic acid from alpha-linolenic acid. Ideally the effects of these fatty acids and their eicosanoid derivatives are tailored to the specific biological needs of the body. The balance between n-3 and n-6 PUFAs is essential for metabolism and maintenance of the functions of both classes. The availability of n-3 long chain PUFAs plays a major role in regulating both fat accumulation and its elimination by the liver. Derangement of hepatic n-6:n-3 PUFA ratio impacts on the histological pattern of fatty liver through modulation of the amount of intrahepatic lipids. Moreover, the influence of PUFAs and their eicosanoid products on hepatic microcirculation and ischemia/reperfusion injury has been demonstrated in many studies. This concise review article will focus on the role of PUFAs and eicosanoids in hepatic steatosis, microcirculation and ischemia/reperfusion injury.

Prevention of reperfusion injury and microcirculatory failure in macrosteatotic mouse liver by omega-3 fatty acids

Macrovesicular hepatic steatosis has a lower tolerance to reperfusion injury than microvesicular steatosis with an abnormally high ratio of omega-6 (n-6): omega-3 (n-3) polyunsaturated fatty acids (PUFAs). We investigated the influence of PUFAs on microcirculation in steatotic livers and the potential to minimize reperfusion injury in the macrosteatotic liver by normalization of PUFAs. Ob/ob mice were used as a model of macrovesicular hepatic steatosis and C57/Bl6 mice fed a choline-deficient diet for microvesicular steatosis. Steatotic and lean livers were subjected to 45 minutes of ischemia and 3 hours of reperfusion. Hepatic content of omega-3 and omega-6 PUFAs was determined. Microcirculation was investigated using intravital fluorescence microscopy. A second group of ob/ob mice was supplemented with dietary omega-3 PUFAs and compared with the control diet-fed group. Microcirculation, AST, and Kupffer cell activity were assessed. Macrosteatotic livers had significant microcirculatory dysfunction correlating with high omega-6: omega-3 PUFA ratio. Dietary omega-3 PUFA resulted in normalization of this ratio, reduction of intrahepatic lipids, and decrease in the extent of macrosteatosis. Defective microcirculation was dramatically ameliorated with significant reduction in Kupffer cell activity and protection against hepatocellular injury both before ischemia and after reperfusion.

CONCLUSION

Macrosteatotic livers disclosed an abnormal omega-6: omega-3 PUFA ratio that correlates with a microcirculatory defect that enhanced reperfusion injury. Thus, protective strategies applied during or after ischemia are unlikely to be useful. Preoperative dietary omega-3 PUFAs protect macrosteatotic livers against reperfusion injury and might represent a valuable method to expand the live liver donor pool.

Stress and fatty liver--possible indications for dietary long-chain n-3 fatty acids

The favourable effects of eicosapentaenoic acid (EPA)- and doco-sahexaenoic acid (DHA)-rich diets (marine fish, fish oil) on several risk factors for cardiovascular disease are well established. The present survey describes possible new indications for diets supplemented with long-chain n-3 fatty acids. During a standardized psychophysiological stress test (arithmetic, sentence completion tasks) systolic blood pressure after 2 weeks of diets supplemented with either 60 ml/day of sunflower or linseed oil was significantly decreased. During the sunflower oil-rich diet 45 g/day of linoleic acid (LA) and during the linseed oil-rich period 38 g/day of alpha-linolenic acid (LNA) were ingested. After a 2-week diet supplemented with mackerel (2 cans/day equivalent to 2.2 g/day of EPA and 2.8 g/day of DHA) systolic and diastolic blood pressure within the same test design appeared significantly lower. After a herring diet providing 2 cans/day, equivalent to 1.0 g of EPA and 1.8 g of DHA, the blood pressure-lowering effect was minor. The increase of thromboxane B2 (TxB2) during the stress test failed to occur after the fish diets. The results suggest a stress-protective effect of polyenoic acid-rich diets, which appears most pronounced and dose-related after long-chain n-3 fatty acids. In human liver an increase of fat droplet size in hepatocytes is associated with a decrease of the percentage of EPA in liver triglycerides. A diminution of plasma free fatty acids (FFA) after a mackerel diet might contribute to a depressed synthesis of liver triglycerides.(ABSTRACT TRUNCATED AT 250 WORDS)

Blood pressure- and lipid-lowering effect of mackerel and herring diet in patients with mild essential hypertension

Fourteen male patients with mild essential hypertension were put on a mackerel and herring diet within a prescribed isocaloric regimen in a cross-over design for 2 weeks. After mackerel diet eicosapentaenoic acid (EPA-C20:5, n-3) appeared more in cholesterol esters (1.7-11.0%), whereas docosahexaenoic acid (DHA-C22:6, n-3) was predominantly incorporated into serum triglycerides (1.0-8.3%). After herring diet, which contained half as much EPA and DHA, their increase was of minor degree. After mackerel diet serum triglycerides, total cholesterol, LDL cholesterol and lecithin cholesterol acyl transferase (LCAT) activity were significantly decreased (by 28%, 9%, 14% and 14%, respectively), returning to the initial levels 3 months later. On the contrary, HDL cholesterol appeared significantly increased (by 12%). After herring diet the differences were not significant. Serum sodium was significantly lower (by 2%) at the end of the mackerel diet as compared to the initial values. On the other hand, uric acid in serum appeared transiently increased (by 24%) at the end of both dietary periods. A significant decrease (by 8%) in casual systolic blood pressure, measured in recumbent position, could be observed only at the end of the mackerel period. Moreover, the level of systolic and diastolic blood pressure before and during a standardized psychophysiological stress test was significantly lower after mackerel diet. Nevertheless, the increments after stress were similar. Plasma renin activity was increased (by 64%) after mackerel diet.(ABSTRACT TRUNCATED AT 250 WORDS)

The plasma and erythrocyte fatty acid composition of poorly controlled, insulin-dependent (type I) diabetic patients and the effect of improved metabolic control

Analysis of the plasma and erythrocyte fatty acid composition of poorly controlled, insulin-dependent (type I) diabetic patients revealed a low level of 18:3c, omega 6, 20:3c, omega 6, 22:6c, omega 3 and total polyunsaturated fatty acids, and a high level of 18:0 and total saturated fatty acids. Improvement of diabetic control, achieved by treatment with continuous subcutaneous insulin infusion coincided with an increase of arachidonic acid and a normalization of total polyunsaturated fatty acids, with a concomitant decrease of total saturated fatty acids and total monounsaturated fatty acids, especially 18:1c, omega 9. The results of this study can be important for the dietary advice to poorly controlled, diabetic patients.

Lipid and blood pressure-lowering effect of mackerel diet in man

Fifteen healthy volunteers were put on a mackerel and herring diet, consisting of a prescribed daily isocaloric regimen in a cross-over design, for 2 weeks. Eicosapentaenoic acid (EPA - C20:5, n-3) was predominantly incorporated into cholesterol esters, whereas docosahexaenoic acid (C22:6, n-3) appeared more in serum triglycerides, indicating that the function of the latter may be different from that of EPA. After mackerel ingestion, serum triglycerides, total cholesterol and lecithin cholesterol acyl transferase (LCAT) activity were significantly decreased, returning to basal levels 3 months later. Low density lipoprotein (LDL) cholesterol, high density lipoprotein (HDL) cholesterol and postheparin lipolytic activity (PHLA) remained unchanged at the end of the mackerel diet. Generally, after the herring diet the differences were minor, only LCAT activity being significantly decreased. A markedly lower systolic and diastolic blood pressure at the end of the mackerel period could be observed. After herring diet a slight diminution of blood pressure was not significant. Accordingly, plasma noradrenaline was only significantly decreased at the end of the mackerel period. Dopamine-beta-hydroxylase (DBH) activity in serum had no differences before, during and after the study. From the data presented it can be said that a mackerel diet exerts a beneficial influence on cardiovascular risk.

Altered microsomal phospholipid composition in the streptozotocin diabetic rat

Streptozotocin diabetes in the rat alters liver microsomal membrane fatty acid composition. The present study was undertaken to determine if such changes in fatty acid composition were due to changes in the amount of individual phosphoglycerides or to disproportionate changes in fatty acid composition in any of the individual phosphoglycerides. The diabetic animals showed a small increase in total microsomal phospholipid, which is due to a selective increase in the phosphatidylethanolamine fraction. The changes in fatty acid composition in the total lipid extract (decreased palmitoleic, oleic and arachidonic acids and increased linoleic and docosahexaenoic acids) from the diabetic animals were present in both the major phosphoglycerides, phosphatidylcholine and phosphatidylethanolamine, with very little change in fatty acid composition in the phosphatidylserine and inositol fraction. Further studies are necessary to delineate the cause of the abnormal membrane phospholipid composition in the diabetic animal.

Inverse relationship between linoleic acid in serum and in adipose tissue of patients with essential hypertension

In patients with labile essential hypertension without and with overweight as well as in normotensive controls the fatty acid pattern of serum triglycerides and subcutaneous adipose tissue was estimated by gas liquid chromatography. In serum triglycerides of hypertensives linoleic acid was increased but appeared decreased in depot fat. This inverse relationship could not be found for arachidonic acid. Correspondingly, the C 18:2/C 20:4-ratio was higher in serum triglycerides than in adipose tissue. Only in depot fat of overweight hypertensives the percentage of arachidonic acid was decreased when compared to subjects with normal body weight. Linolenic acid remained unchanged in serum triglycerides but decreased significantly in adipose tissue of hypertensive patients. Eicosapentaenoic acid was increased in serum triglycerides and depot fat of patients with essential hypertension of normal body weight. The results are discussed with respect to the possible pathogenesis of essential hypertension and the hypotensive potency of dietary linoleic acid which has been described in patients with high blood pressure.

The dominant diseases of modernized societies as omega-3 essential fatty acid deficiency syndrome: substrate beriberi

About 1900, modern food selection and processing caused widespread epidemics of the B vitamin deficiency diseases of beriberi and pellagra which, for genetic reasons, often expressed as different diseases ranging from bowel and heart disease to dermatoses and psychoses. But the B vitamins merely help convert essential fatty acids (EFA) into the prostaglandin (PG) tissue regulators and it now turns out that, through hydrogenation, milling and selection of w3-poor southern foods, we have also been systematically depleting, by as much as 90%, a newly discovered trace Nordic EFA (w3) of special importance to primates and sole precursor of the PG3(4) series, even as a concurrent fiber deficiency increases body demand for EFA. Since substrate EFA is processed by many B vitamin catalysts, an EFA deficiency will mimic a panhypovitaminosis B, i.e., a mixture of substrate beriberi and substrate pellagra resembling vitamin beriberi and pellagra but exhibiting as even more diverse endemic disease. This would constitute a second stage of the Modern Malnutrition and explain why some workers now hold the dominant diseases of modernized societies to be new, nutritionally based, pellagraform yet lipid-related and to range, once again, from heart disease to psychosis. It is an assumption that our dominant diseases are unrelated to each other or are merely revealed by out diagnostic acumen and therapeutic success; and that hydrogenating millions of tons of food oils annually, to destroy the rancidity producing w30EFA, is safe for primates. Extensive beriberiform disease is reported here in 32 typical cases taken from medical practice which responds strikingly to linseed oil supplements (60% w3-EFA) in confirmation of identical results in Capuchins.