Novel Approaches for Omega-3 Fatty Acid Therapeutics: Chronic Versus Acute Administration to Protect Heart, Brain, and Spinal Cord.

This article reviews novel approaches for omega-3 fatty acid (FA) therapeutics and the linked molecular mechanisms in cardiovascular and central nervous system (CNS) diseases. In vitro and in vivo research studies indicate that omega-3 FAs affect synergic mechanisms that include modulation of cell membrane fluidity, regulation of intracellular signaling pathways, and production of bioactive mediators. We compare how chronic and acute treatments with omega-3 FAs differentially trigger pathways of protection in heart, brain, and spinal cord injuries. We also summarize recent omega-3 FA randomized clinical trials and meta-analyses and discuss possible reasons for controversial results, with suggestions on improving the study design for future clinical trials. Acute treatment with omega-3 FAs offers a novel approach for preserving cardiac and neurological functions, and the combinations of acute treatment with chronic administration of omega-3 FAs might represent an additional therapeutic strategy for ameliorating adverse cardiovascular and CNS outcomes.

A combined natural supplement lowers LDL cholesterol in subjects with moderate untreated hypercholesterolemia: a randomized placebo-controlled trial.

OBJECTIVE: To investigate the effect of a natural cholesterol-lowering supplement (NCLS) containing red yeast rice, policosanols and artichoke leaf extracts on blood lipid concentrations as well as on safety parameters when given over 16 weeks in 100 volunteers with untreated moderate hypercholesterolemia, in a randomized, double-blind, placebo-controlled trial. RESULTS: Reduction of primary outcome low-density lipoprotein cholesterol [-0.22 g/L (95% confidence interval, CI: -0.31 to -0.12) corresponding to -14.3% from baseline (95% CI: -21.5 to -7.2) compared to placebo], as well as total cholesterol, apolipoprotein B100 and apolipoprotein B100/apolipoprotein A-I ratio, were observed after 16 weeks of supplementation with NCLS. These effects were already observed at Week 4 and 10 of supplementation. No significant changes were observed in high-density lipoprotein, triacylglycerol, creatine kinase, lactate dehydrogenase and coenzyme Q10 levels, as well as in markers of liver and renal function. CONCLUSIONS: The NCLS was effective in reducing low-density lipoprotein cholesterol and apolipoprotein B100 in subjects with moderate hypercholesterolemia, without modifying safety parameters.

Seasons but not ethnicity influence urinary iodine concentrations in Belgian adults.

BACKGROUND: Mild iodine deficiency (MID) is endemic in Belgium. Previous surveys, which assessed iodine nutrition in Belgium, focused on children. The iodine status of adults and the influence of ethnicity or seasonality on urinary iodine concentrations (UIC) have not been investigated. Since the nutritional profile of children differs from that of adults, we may anticipate similar differences in iodine status. Seasonal fluctuations in UIC have also been reported from other MID regions. AIM OF THE STUDY: We aimed at assessing iodine status and its association with ethnicity and seasonality in adults. METHODS: A stratified random sample of 401 healthy subjects aged between 40 and 60 years, of Belgian, Moroccan, Turkish and Congolese descent residing in Brussels was obtained. Iodine status and thyroid function were determined. RESULTS: Median UIC was 68 µg/L. The frequency of UIC below 100 µg/L was 73.3%, of which 41.9% fell between 50 and 99 µg/L, and 29.8% between 49 and 20 µg/L. There was no difference in UIC and thyroid function between subjects of different ethnic origins. The frequency of UIC below 50 µg/L was higher in the fall-winter compared to spring-summer periods (P = 0.004). Serum FT3 concentrations, but not FT4 and TSH, were significantly greater in winter than in summer. CONCLUSION: Seasonal fluctuations in UIC suggest that the risk of iodine deficiency among adults living in Brussels is higher in fall-winter than in spring-summer. The prevalence of MID in Brussels is high among adults but ethnicity does not appear to influence iodine status.

Blood clearance kinetics and organ delivery of medium-chain triglyceride and fish oil-containing lipid emulsions: Comparing different animal species.

BACKGROUND & AIMS: Medium-chain triglycerides (TG) (MCT) and fish oil (FO) TG are incorporated as the core TG component into intravenous (IV) lipid emulsions for infusion in parenteral nutrition. Bolus injections of IV emulsions, on the other hand, have emerged as a novel therapeutic approach to treat various acute disorders. However, intravascular metabolism and organ delivery of acute IV injection of emulsions containing both MCT and FO are not fully defined, nor have they been characterized across common experimental animal models. We characterized and compared blood clearance kinetics and organ distribution of bolus injections of MCT/FO emulsions among different animal species. We also examined whether sex differences or feeding status can affect catabolic properties of MCT/FO lipid emulsions. DESIGN: Blood clearance rates of lipid emulsions with specific TG composition were compared in rats IV injected with [3H]cholesteryl hexadecyl ether labeled pure n-6 long-chain (LCT) and n-3 FO TG lipid emulsions, or emulsions containing MCT and FO at different ratios (wt/wt), which include 8:2 (80% MCT: 20% FO), 5:4:1 (50% MCT: 40% LCT: 10% FO) and SMOF (30% LCT: 30% MCT: 25% olive oil: 10% FO). Dose-response effects (0.016 mg-1.6 mg TG/g body weight) of the MCT/FO 8:2 emulsions on blood clearance properties and organ delivery were determined in both mice and rats. Blood clearance kinetics and organ uptake of MCT/FO 8:2 emulsions were compared between male and female rats and between fed and fasted rats. Changes in plasma lipid profiles after acute injections of MCT/FO 8:2 lipid emulsion at different doses (0.043, 0.133, and 0.4 mg TG/g body weight) were characterized in non-human primates (Cynomolgus monkeys). RESULTS: MCT/FO 8:2 emulsion was cleared faster in rats when compared with other emulsions with different TG contents. Mice had faster blood clearance and higher fractional catabolic rates (FCR) when compared with the rats injected with MCT/FO 8:2 emulsions regardless of the injected doses. Mice and rats had similar plasma TG and free fatty acid (FFA) levels after low- or high-dose injections of the MCT/FO emulsion. Tissue distribution of the MCT/FO 8:2 lipid emulsion are comparable between mice and rats, where liver had the highest uptake per recovered dose among all organs (>60%). Feeding status and sex differences did not alter the blood clearance rate of the MCT/FO 8:2 emulsion in rats. In a nonhuman primate model, dose-response increases in plasma TG and FFA were observed after IV injection of MCT/FO 8:2 emulsions within the 1st 10 min. CONCLUSION: A lipid emulsion containing both MCT and FO TG is cleared rapidly in blood and readily available for organ uptake in rodent and primate animal models. Characterization of the blood clearance properties of the MCT/FO 8:2 emulsion administered in various animal models may provide further insight into the safety and efficacy profiles for future therapeutic use of bolus injections of MCT/FO emulsions in humans.

Lipid peroxidation is not a prerequisite for the development of obesity and diabetes in high-fat-fed mice.

The mechanism, by which a high-fat (HF) diet could impair glucose metabolism, is not completely understood but could be related to inflammation, lipotoxicity and oxidative stress. Lipid peroxides have been proposed as key mediators of intracellular metabolic response. The purpose of the present study was to analyse, in mice fed with a HF diet, the possible association between obesity and glucose tolerance on the one hand, and between oxidative stress and lipid peroxidation on the other hand. The present results show that a HF diet (70 % energy as fat), v. a high-carbohydrate chow diet (control), increases body weight and fat mass development, and impairs glycaemia and insulinaemia within 4 weeks. It also promotes the expression of NADPH oxidase in the liver--signing both oxidative and inflammatory stress--but decreases thiobarbituric acid-reactive substances content in the liver as well as in epididymal, subcutaneous and visceral adipose tissues. HF diet, with elevated vitamin E content, induces high concentration of alpha-tocopherol in liver and adipose tissues, which contributes to the protection against lipid peroxidation. Thus, lipid peroxidation in key organs is not necessarily related to the development of metabolic disorders associated with diabetes and obesity.

The metabolic syndrome of omega3-depleted rats. III. Brain phospholipids.

Rats exposed from 7 weeks after birth and for the ensuing 3 to 7 months to a diet depleted in long-chain polyunsaturated omega3 fatty acids were recently proposed as a new animal model for the metabolic syndrome. The present study aimed mainly at investigating whether, in this new model, the perturbation of the fatty acid total content and pattern of brain phospholipids simulates that previously documented in second-generation omega3-depleted rats. Such was indeed the case, with the apparent exception of changes in the C18:1omega9, C20:0, C22:0 and C24:0 relative content of brain phospholipids. Moreover, the C22:5omega3 content of such phospholipids was unexpectedly lower in the present model than in the second-generation omega3-depleted rats. The changes in brain phospholipids were also monitored when the rats deprived of omega3 fatty acids for 7 months were given access for 2 to 4-5 weeks to a flaxseed oil-enriched diet. Most phospholipid variables were rapidly normalized under the latter experimental conditions. The results obtained under these conditions suggest that an increase in the brain phospholipid C22:5omega3 content may play a key role in the orexigenic effects of exogenous omega3 fatty acids supplied to omega3-depleted animals.

The metabolic syndrome of omega3-depleted rats. II. Body weight, adipose tissue mass and glycemic homeostasis.

Exposure of 7-week-old normal rats for 3-7 months to a diet deprived of long-chain polyunsaturated omega3 fatty acids was recently reported to induce changes in the fatty acid content and pattern of liver phospholipids and triglycerides similar to those otherwise found in second generation omega3-depleted rats. In the present study, the changes in body weight, parametrial adipose tissue mass, plasma glucose and insulin concentrations and insulin resistance index were investigated in the same control and omega3-depleted rats, which were then given access for 2 to 4-5 weeks to either a flaxseed oil-enriched diet (control and omega3-depleted rats) or a soybean oil-enriched diet (control rats). The body weight failed to differ between control and omega3-depleted rats. The latter rats, however, displayed increases in adipose tissue mass, plasma glucose and insulin concentrations, and insulin resistance index. In the control rats given access to the soybean or flaxseed oil-enriched diet, body weight and adipose tissue mass were little affected, but both the plasma glucose concentration and insulin resistance index decreased. In the omega3-depleted rats given access to the flaxseed oil-enriched diet, both body weight and adipose tissue mass underwent a rapid, pronounced and sustained increase, whilst the plasma glucose concentration and insulin resistance index decreased similarly to those in the control rats. The present design of omega3 fatty acid dietary deprivation thus reproduces the visceral obesity and insulin resistance otherwise observed in second-generation omega3-depleted rats. However, the supply of exogenous omega3 fatty acids to the omega3-depleted rats failed to oppose visceral obesity, possibly as a result of the orexigenic effects of these omega3 fatty acids.

The metabolic syndrome of omega3-depleted rats. I. Liver data.

Second-generation rats depleted in long-chain polyunsaturated omega3 fatty acids were recently proposed as a novel animal model for the metabolic syndrome. In the present study, a dietary deprivation of omega3 acids for 3-7 months was found sufficient to provoke in 6-week-old normal rats the same alteration of the fatty acid content and profile of liver phospholipids and triglycerides as that otherwise prevailing in the second-generation omega3-depleted rats, with emphasis on a severe decrease in their omega3 fatty acid content, alterations in the relative contribution of and ratio between selected long-chain polyunsaturated omega6 fatty acids, saturated and monodesaturated fatty acids and precursors of nervonic acid, and liver steatosis. When the omega3-depleted rats were exposed, after the first 7 months of the present experiments and for 2-4 weeks to a diet supplemented with 5% (w/w) flaxseed oil, most of these hepatic variables returned towards or beyond control values. In both the omega3-depleted rats and control animals, however, the eventual exposure to the flaxseed oil-enriched diet failed to suppress liver steatosis and, on the contrary, provoked a further increase in liver triglyceride content. It is proposed, therefore, that the present approach represents a simple and realistic animal model to study the consequences of omega3-depletion. Moreover, the results suggest that to oppose such consequences, e.g. liver steatosis, it may be necessary to combine the dietary supply of omega3 acids with a suitable control of food intake, in both qualitative and quantitative terms.

Alteration of lipid fatty acid profile and cationic fluxes in ventricular cardiomyocytes from omega3-depleted rats.

The bolus intravenous injection of a medium-chain triglyceride:fish oil emulsion was recently found to increase within 60 min the cell phospholipid content in long-chain polyunsaturated omega3 fatty acids and, hence, proposed as a potential tool to prevent cardiac arrhythmia in subjects with a decreased dietary intake of such fatty acids. In the present study, ventricular cardiomyocytes from second generation rats depleted in omega3 fatty acids were found to display the same changes in the phospholipid fatty acid pattern as that previously documented in the cardiac muscle and endothelium of such rats, altered 86Rb and 45Ca fluxes with emphasis on a decrease in both K+ inflow and K+ content and an increase in both Ca2+ inflow and content. The alteration of K+ inflow could not be attributed to a decrease in ouabain-sensitive Na+,K+-ATPase activity as measured in cell homogenates. The cationic alterations were corrected, in part at least, by the prior intravenous injection of the medium-chain triglyceride:fish oil emulsion 60 min before sacrifice of the omega3-depleted rats.

Vitamin D deficiency and hyperparathyroidism in relation to ethnicity: a cross-sectional survey in healthy adults.

BACKGROUND: The study of vitamin D status at population level gained relevance since vitamin D deficiency was recently suggested to trigger chronic disease. AIM OF THE STUDY: We aimed to describe vitamin D status, its association with bone and mineral metabolism and risk factors for deficiency in adults over 40 years in Belgium. METHODS: We conducted a cross-sectional survey in a stratified random sample of 401 subjects aged between 40 and 60 years living in Brussels, and drawn from 4 different ethnic backgrounds: autochthonous Belgian, Moroccan, Turkish and Congolese. 25-Hydroxyvitamin D (25OHD), parathyroid hormone (PTH), osteocalcin, C-telopeptide and bone mineral density was measured. RESULTS: Three-hundred and six subjects (77%) showed 25OHD concentrations below 50 nmol/l,135 (34%) below 25 nmol/l and 18 (5%) below 12.5 nmol/l. The proportion of subjects with vitamin D deficiency was four times greater amongst those of Moroccan or Turkish descent compared with those of Congolese or Belgian descent. Moroccan subjects showed a significant higher PTH and bone marker concentrations compared to Belgian. Ethnicity, season and sex were independently associated with vitamin D deficiency in multivariate analysis. CONCLUSION: The prevalence of vitamin D deficiency is very high amongst the adult population of Brussels but immigrants are at greater risk. Given the established link between population health and adequate vitamin D status, a policy of vitamin D supplementation should be considered in these risk groups.

CD36 and proteoglycan-mediated pathways for (n-3) fatty acid enriched triglyceride-rich particle blood clearance in mouse models in vivo and in peritoneal macrophages in vitro.

Because the mechanisms of (n-3) fatty acid-enriched triglyceride-rich particle [(n-3)-TGRP] uptake are not well characterized, we questioned whether (n-3)-TGRP are removed via "nonclassical" pathways, e.g., pathways other than an LDL receptor and/or involving apolipoprotein E (apoE). Chylomicron-sized model (n-3)-TGRP labeled with [3H]cholesteryl ether were injected into wild-type (WT) and CD36 knockout (CD36-/-) mice at low, nonsaturating and high, saturating doses. Blood clearance of (n-3)-TGRP was determined by calculating fractional catabolic rates. At saturating doses, blood clearance of (n-3)-TGRP was slower in CD36-/- mice relative to WT mice, suggesting that in part CD36 contributes to (n-3)-TGRP uptake. To further examine the potential nonclassical clearance pathways, peritoneal-elicited macrophages from WT and CD36-/- mice were incubated with (n-3)-TGRP in the presence of apoE, lactoferrin, and/or sodium chlorate. Cellular (n-3)-TGRP uptake was measured to test the roles of apoE-mediated pathways and/or proteoglycans. ApoE-mediated pathways compensated in part for defective (n-3)-TGRP uptake in CD36-/- cells. Lactoferrin decreased (n-3)-TGRP uptake in the presence of apoE. Inhibition of cell proteoglycan synthesis by chlorate reduced (n-3)-TGRP uptake in both groups of macrophages, and chlorate effects were independent of apoE. We conclude that although CD36 is involved, it is not the primary contributor to the blood clearance of (n-3)-TGRP. The removal of (n-3)-TGRP likely relies more on nonclassical pathways, such as proteoglycan-mediated pathways.

Preferential enrichment of liver phospholipids in docosahexaenoate relative to eicosapentaenoate in omega-3-depleted rats injected with a medium-chain triglyceride: fish oil emulsion.

The bolus intravenous injection of a novel medium-chain triglyceride:fish oil (FO) emulsion was recently proposed as a tool to provoke a rapid enrichment of cell phospholipids in long-chain polyunsaturated omega-3 fatty acids. In the present study, the enrichment of liver phospholipids and triglycerides in C20:5omega-3, C22:5omega-3 and C22:6omega-3 was assessed 60min after the intravenous administration of FO (1.0ml) to second-generation omega-3-depleted rats. When compared to uninjected rats, or animals injected with a control omega-3 fatty acid-poor medium-chain triglyceride:olive oil (OO) emulsion, the enrichment of liver phospholipids, and to a lesser extent liver triglycerides, attributable to the injection of the FO emulsion was more pronounced for C22:6omega-3 than C20:5omega-3, despite the presence of equal amounts of these two omega-3 fatty acids in the injected diglycerides and triglycerides. The possible determinants and potential beneficial effects of such a difference are briefly discussed.

Perturbation of 11-eicosenoate metabolism in female diabetic rats.

Considering the proposed preventive effect of nervonic acid on obesity- and diabetes-related coronary risk factors, the content of its precursors (oleic, 11-eicosenoic and 13-docosenoic acids) was measured in liver and plasma phospholipids and triglycerides, brain and spleen phospholipids, and adipose tissue lipids of fed or overnight fasted control and hereditarily diabetic Goto-Kakizaki female rats, as well as fed streptozotocin-induced diabetic female rats. In liver and brain phospholipids, the 11-eicosenoate/oleate ratio was significantly higher in diabetic rats than in control animals. Such was not the case in either spleen phospholipids or liver triglycerides and adipose tissue lipids. The increase in the liver phospholipid 11-eicosenoate/oleate ratio found in female diabetic rats represents a mirror image of the situation recently documented, in the same animal models of diabetes, in male rats. These contrasting findings may be relevant to the higher coronary heart disease risk prevailing in female, as compared to male, diabetic subjects.

Hemostatic safety of the bolus intravenous injection of a novel medium-chain triglyceride:fish oil emulsion.

The bolus intravenous injection of a novel 8:2 medium-chain triglyceride:fish oil emulsion was recently found to increase within 60 min and for the subsequent 24-48 h the long-chain polyunsaturated omega3 fatty acid content of both leucocyte and platelet phospholipids in 12 normal subjects. The aim of the present report is to document the hemostatic safety of such a procedure in the same 12 subjects. No adverse effect was found when comparing the results obtained after administration of either the fish oil-containing emulsion or a control 5:5 medium-chain triglyceride:soybean triglyceride emulsion, whether in terms of the occlusion time in either an ADP or epinephrine test or in terms of the [CD]42b, [CD]62p, fibrinogen and PAC-1 response to ADP, collagen or thrombin receptor analog peptide 6 in platelets examined by fluorescence activated cell sorting. In conclusion, this novel procedure for the rapid enrichment of cell phospholipid in long-chain polyunsaturated omega3 fatty acids presents the required safety in a hemostatic perspective.

Correlation between liver and plasma fatty acid profile of phospholipids and triglycerides in rats.

Considering the changes in the fatty acid profile of liver lipids related to age, gender and nutritional status or occurring in pathological situations, this study aimed at investigating whether such changes could be judged from measurements conducted in plasma lipids. The fatty acid profile of both liver and plasma phospholipids and triglycerides was measured in 16 control animals and 26 rats depleted in long-chain polyunsaturated (n-3) fatty acids. Within each group of rats, significant correlations prevailed between the percentage of each fatty acid in liver versus plasma phospholipids or triglycerides. However, the plasma/liver ratio for the relative content of C20:5(n-3), C22:5(n-3) and C22:6(n-3) in triglycerides displayed abnormally high values in 2 control animals. The fatty acid profile of liver phospholipids and triglycerides can, as a rule, be judged from measurements made in the corresponding plasma lipids. For instance, measurements in plasma phospholipids could help to identify subjects deficient in (n-3) fatty acids and to assess the dietary correction of this defect.

Rapid lipid enrichment in omega3 fatty acids: plasma data.

The bolus intravenous injection of a novel medium-chain triglyceride:fish oil emulsion to normal subjects was recently reported to enrich within 60 min the phospholipid content of leucocytes and platelets in long-chain polyunsaturated omega3 fatty acids. The present study, conducted in second generation omega3-depleted rats, aimed at investigating whether such a procedure may also increase within 60 min the phospholipid content of omega3 fatty acids in cells located outwards the bloodstream, in this case liver cells, and whether this coincides with correction of the perturbation in the liver triglyceride fatty acid content and profile otherwise prevailing in these rats. This first report deals mainly with the fatty acid pattern of plasma lipids in male omega3-depleted rats that were non-injected or injected with either the omega3-rich emulsion or a control medium-chain triglyceride:olive oil emulsion. The results provide information on the fate of the exogenous lipids present in the lipid emulsions and injected intravenously 60 min before sacrifice. Moreover, in the uninjected omega3-depleted rats the comparison between individual plasma and liver measurements indicated positive correlations in the fatty acid profile of phospholipids and triglycerides.

Rapid lipid enrichment in omega3 fatty acids: cause-to-effect relationships.

The bolus intravenous administration of a novel medium-chain triglyceride:fish oil emulsion to second generation rats depleted in long-chain polyunsaturated omega3 fatty acids was recently found to enrich within 60 min the content of both plasma and liver lipids in such omega3 fatty acids, this coinciding with correction of the perturbation in liver triglyceride fatty acid content and profile otherwise prevailing in these rats. The present report draws attention to cause-to-effect relationships between changes in liver phospholipid and triglyceride fatty acid content and/or pattern operative under these experimental conditions.

Rapid lipid enrichment in omega3 fatty acids: liver data.

The bolus intravenous injection of a novel medium-chain triglyceride:fish oil emulsion to normal subjects was recently reported to enrich within 60 min the phospholipid content of leucocytes and platelets in long-chain polyunsaturated omega3 fatty acids. The present study, conducted in second generation omega3-depleted rats, aims at investigating whether such a procedure may also increase within 60 min the phospholipid content of omega3 fatty acids in cells located outwards of the bloodstream, in this case liver cells, and whether this coincides with correction of the perturbation in the liver triglyceride fatty acid content and profile otherwise prevailing in these rats. The results indicate that such is indeed the case and further suggest a cause-to-effect relationship between the two events.

Fatty acid profile of plasma and liver lipids in mice depleted in long-chain polyunsaturated (n-3) fatty acids.

Considering the numerous features of the metabolic syndrome found in rats depleted in long-chain polyunsaturated (n-3) fatty acids and in the perspective of further work conducted in (n-3)-depleted mice, the fatty acid profile of plasma and liver lipids was assessed in both male and female control and second-generation (n-3)-depleted mice. In addition to gender differences, the major alteration found in the (n-3)-depleted animals consisted in the expected severe depletion of plasma triacylglycerols and phospholipids, as well as liver phospholipids, in C20:5(n-3), C22:5(n-3) and C22:6(n-3). In plasma triacylglycerols, the weight percentages of C18:2(n-6) and C18:3(n-6) were lower in (n-3)-depleted mice than in control animals. In both plasma and liver phospholipids, however, the weight percentages of long-chain polyunsaturated (n-6) fatty acids (C20:4(n-6) and C22:4(n-6)) were higher in (n-3)-depleted mice than in control animals. The C16:1(n-7)/C16:0 and C18:1(n-9)/C18:0 ratio in both plasma and liver phospholipids were also increased in female (n-3)-depleted mice but not so in male animals. Highly significant correlations were found between the weight percentage of each fatty acid in liver versus plasma phospholipids. Taken as a whole, these findings indicate that second-generation mice depleted in (n-3) fatty acids represent a suitable model, in terms of the remodelling of the fatty acid profile in plasma and liver lipids, to investigate the metabolic and functional consequences of such a depletion.

L-glutamine and palmitate catabolism in pancreatic islets from rats depleted in long-chain polyunsaturated omega 3 fatty acids.

The catabolism of D-glucose was recently found to be impaired in pancreatic islets from rats depleted in long-chain polyunsaturated omega3 fatty acids. The specificity of this alteration was now investigated by characterizing the oxidative fate of endogenous nutrients in islets preincubated with either L-[U-14C]glutamine or [U-14C]palmitate and then incubated variously in the absence of D-glucose, presence of the hexose or presence of metabolic poisons. Relative to their radioactive content after preincubation, the production of 14CO2 by islets prelabelled with [U-14C]glutamine was higher in omega3-depleted rats than control animals. The enhancing action of D-glucose upon such production was impaired, however, in the omega3-depleted rats. The net uptake of 14C-palmitate and absolute value for 14CO2 output were both increased in omega3-depleted rats, whilst the ratio between 14CO2 output and islet radioactive content was decreased in the same animals. The inhibition of 14CO2 production by metabolic poisons was comparable in all cases. These results are consistent with recent findings on such items as the availability of endogenous amino acids and uptake of unesterified fatty acids in extrapancreatic sites of the omega3-depleted rats. They also support the view that the alteration of D-glucose metabolism in the islets of the latter animals may be attributable, in part at least, to alteration of glucokinase kinetics by high intracellular acyl-CoA levels.