Therapeutic effects of larger doses of arachidonic acid added to DHA on social impairment and its relation to alterations of polyunsaturated fatty acids in individuals with autism spectrum disorders

The polyunsaturated fatty acids (PUFAs), arachidonic acid (ARA) and docosahexaenoic acid (DHA) may play key roles in brain network maturation. ARA plays an important role in signal transduction related to neuronal maturation. This study aims to evaluate the efficacy of supplementing with larger doses of ARA added to DHA in a double-blind, placebo-controlled 16-week trial. To confirm findings observed in the placebo-controlled trial, an additional 16-week open-label study was further conducted. To examine the relationship between the efficacy of the supplementation regimen and alterations in PUFAs levels, we examined plasma levels of PUFAs. We used the Social Responsiveness Scale (SRS) and the Aberrant Behavior Checklist-Community (ABC) to estimate psychotic symptoms. Repeated measures ANOVA revealed that this supplementation significantly improved SRS-measured communication as well as ABC-measured social withdrawal during the placebo-controlled trial. The treatment effect sizes were more favorable for the treatment group compared with the placebo group (communication: 0.87 vs. 0.44; social withdrawal: 0.88 vs. 0.54). At the end of the placebo-controlled trial, there was a significant difference in the change in plasma ARA levels from the baseline and a trend towards a significant difference in plasma ARA levels between the two groups. The open-label study was not powered to detect significant improvements in the outcome measures or significant differences in plasma ARA levels. The present clinical trials suggest that supplementation with larger ARA doses added to DHA improves social impairment in individuals with ASD via ARA-induced upregulation of neuronal functioning.     

Relationship between hippocampal arachidonic acid content and induction of LTP in aged rats]

There are several lines of evidence indicating that membrane AA correlates with the ability of aged rats to sustain LTP. The age-related decrease in membrane AA seems to be triggered by increased lipid peroxidation, which is involved with the decline of LTP. The chronic treatment of DHA could decrease membrane AA without an increase in lipid peroxidation. We have thus investigated the effect of chronic treatment of DHA on hippocampal LTP to assess whether the decrease in membrane AA could directly affect the induction of LTP. The effects of daily supplementation of DHA for 3 months on membrane AA, LTP, and Ca2+ response were evaluated using hippocampal slices from 26-month-old Wistar rats. Chronic treatment of DHA reduced the hippocampal AA significantly, but did not change the amplitude of LTP. Neither 30 mM K+ nor 500 microM NMDA-induced Ca2+ response was affected by chronic treatment of DHA, while the 500 microM carbachol-induced Ca2+ response was reduced. From these results, the reduction of membrane AA might suppress the carbachol-induced Ca2+ response by inhibiting the muscarinic receptor function, IP3 formation and/or Ca2+ release from Ca2+ stores by IP3. However, the reduction of membrane AA is not likely to be a main causal factor of the decline of LTP.     

Effects of Docosahexaenoic Acid on Neurotransmission

Docosahexaenoic acid (DHA) is the major polyunsaturated fatty acid (PUFA) in the brain and a structural component of neuronal membranes. Changes in DHA content of neuronal membranes lead to functional changes in the activity of receptors and other proteins which might be associated with synaptic function. Accumulating evidence suggests the beneficial effects of dietary DHA supplementation on neurotransmission. This article reviews the beneficial effects of DHA on the brain; uptake, incorporation and release of DHA at synapses, effects of DHA on synapses, effects of DHA on neurotransmitters, DHA metabolites, and changes in DHA with age. Further studies to better understand the metabolome of DHA could result in more effective use of this molecule for treatment of neurodegenerative or neuropsychiatric diseases.     

Effects of large doses of arachidonic acid added to docosahexaenoic acid on social impairment in individuals with autism spectrum disorders: a double-blind, placebo-controlled, randomized trial

Autism spectrum disorders are a neurodevelopmental disorders with reduced cortical functional connectivity relating to social cognition. Polyunsaturated fatty acids arachidonic acid (ARA) and docosahexaenoic acid (DHA) may have key role in brain network maturation. In particularly, ARA is important in signal transduction related to neuronal maturation. Supplementation with larger ARA doses added to DHA may therefore mitigate social impairment. In a 16-week, double-blind, randomized, placebo-controlled trial, we evaluated the efficacy of supplementation with large doses of ARA added to DHA (n = 7) or placebo (n = 6) in 13 participants (mean age, 14.6 [SD, 5.9] years). To examine underlying mechanisms underlying the effect of our supplementation regimen, we examined plasma levels of antioxidants transferrin and superoxide dismutase, which are useful markers of signal transduction. The outcome measures were the Social Responsiveness Scale and the Aberrant Behavior Checklist-Community. Repeated-measures analysis of variance revealed that our supplementation regimen significantly improved Aberrant Behavior Checklist-Community-measured social withdrawal and Social Responsiveness Scale-measured communication. Treatment effect sizes were more favorable for the treatment group compared with the placebo group (communication: treatment groups, 0.87 vs, placebo, 0.44; social withdrawal: treatment groups, 0.88, vs placebo, 0.54). There was a significant difference in the change in plasma transferrin levels and a trend toward a significant difference in the change in plasma superoxide dismutase levels between the 2 groups. This preliminary study suggests that supplementation with larger ARA doses added to DHA improves impaired social interaction in individuals with autism spectrum disorder by up-regulating signal transduction.     

Cardiovascular protective effects of n-3 polyunsaturated fatty acids with special emphasis on docosahexaenoic acid

It is widely accepted that n-3 polyunsaturated fatty acids (PUFAs) rich in fish oils protect against several types of cardiovascular diseases such as myocardial infarction, arrhythmia, atherosclerosis, or hypertension. Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) may be the active biological components of these effects. Although the precise cellular and molecular mechanisms underlying the beneficial effects are still uncertain, the protective effects of n-3 PUFAs are attributable to their direct effects on vascular smooth muscle cell (VSMC) functions. These n-3 PUFAs activate K(+)(ATP) channels and inhibit certain types of Ca(2+) channels, probably via at least 2 distinct mechanisms. N-3 PUFAs favorably alter the eicosanoid profile and regulate cytokine-induced expression of inducible nitric oxide synthase and cyclooxygenase-2 via mechanisms involving modulation of signaling transduction events. N-3 PUFAs also modulate VSMC proliferation, migration, and apoptosis. These recent data suggest that modulation of these VSMC functions contribute to the beneficial effects of n-3 PUFAs on various cardiovascular disorders. Furthermore, recent studies strongly suggest that DHA has more potent and beneficial effects than EPA. However, many questions about the cellular and molecular mechanisms still remain to be answered.     

Evaluation of bioequivalency and toxicological effects of three sources of arachidonic acid (ARA) in domestic piglets

Arachidonic acid (ARA) and docosahexaenoic acid (DHA) are routinely added to infant formula to support growth and development. We evaluated the bioequivalence and safety of three ARA-rich oils for potential use in infant formula using the neonatal pig model. The primary outcome for bioequivalence was brain accretion of ARA and DHA. Days 3-22 of age, domestic pigs were fed one of three formulas, each containing ARA at ∼0.64% and DHA at ∼0.34% total fatty acids (FA). Control diet ARA was provided by ARASCO® and all diets had DHA from DHASCO® (Martek Biosciences Corp., Columbia, MD). The experimental diets a1 and a2 provided ARA from Refined Arachidonic acid-rich Oil (RAO; Cargill, Inc., Wuhan, China) and SUNTGA40S (Nissui, Nippon Suisan Kaisha, Ltd., Tokyo, Japan), respectively. Formula intake and growth were similar across all diets, and ARA was bioequivalent across treatments in the brain, retina, heart, liver and day 21 RBC. DHA levels in the brain, retina and heart were unaffected by diet. Liver sections, clinical chemistry, and hematological parameters were normal. We conclude that RAO and SUNTGA40S, when added to formula to supply ∼0.64% ARA are safe and nutritionally bioequivalent to ARASCO in domestic piglets.     

Safety evaluation of sources of docosahexaenoic acid and arachidonic acid for use in infant formulas in newborn piglets.

Human milk provides small quantities of preformed docosahexaenoic acid (DHA) and arachidonic acid (ARA), usually less than 1% of total fatty acids. Vegetable oil blends commonly used in infant formulas have, until recently, provided the essential fatty acid precursors for these long-chain polyunsaturated fatty acids (LCPUFA), but no preformed DHA and ARA. This study evaluated the safety of ingredient sources of DHA and ARA for use in infant formulas in a neonatal piglet model. Newborn piglets were allowed to suckle for 3 days and then divided into 4 feeding groups of 6 males and 6 females. Piglets were bottle-fed at frequent feeding intervals until 19 days of age. The composition of the piglet formulas was modeled after standard milk-based formulas for human infants while meeting nutritional requirements for piglets. Formulas were a control formula (no added DHA or ARA), a DHA formula providing 55 mg DHA/100 Cal, an ARA formula providing 96 mg/100 Cal ARA, and a DHA+ARA formula providing 34 mg DHA and 62 mg ARA/100 Cal. All formulas were equal in fat content and provided approximately 1000 Cal/l. The ARA-rich oil was from a fermentation product of Mortierella alpina (40 wt.% fatty acids as ARA) and DHA was from high DHA tuna oil (25 wt.% fatty acids as DHA). There were no test article related effects of DHA and/or ARA indicative of an adverse health consequence to the animals seen in the clinical signs, body weights, food consumption, clinical chemistry, hematology, organ weights or gross or histopathology. The findings in this neonatal animal study support the safety of these ingredient oil sources of DHA and ARA for use in infant formulas.     

Health benefits of docosahexaenoic acid (DHA)

Docosahexaenoic acid (DHA) is essential for the growth and functional development of the brain in infants. DHA is also required for maintenance of normal brain function in adults. The inclusion of plentiful DHA in the diet improves learning ability, whereas deficiencies of DHA are associated with deficits in learning. DHA is taken up by the brain in preference to other fatty acids. The turnover of DHA in the brain is very fast, more so than is generally realized. The visual acuity of healthy, full-term, formula-fed infants is increased when their formula includes DHA. During the last 50 years, many infants have been fed formula diets lacking DHA and other omega-3 fatty acids. DHA deficiencies are associated with foetal alcohol syndrome, attention deficit hyperactivity disorder, cystic fibrosis, phenylketonuria, unipolar depression, aggressive hostility, and adrenoleukodystrophy. Decreases in DHA in the brain are associated with cognitive decline during aging and with onset of sporadic Alzheimer disease. The leading cause of death in western nations is cardiovascular disease. Epidemiological studies have shown a strong correlation between fish consumption and reduction in sudden death from myocardial infarction. The reduction is approximately 50% with 200 mg day(-1)of DHA from fish. DHA is the active component in fish. Not only does fish oil reduce triglycerides in the blood and decrease thrombosis, but it also prevents cardiac arrhythmias. The association of DHA deficiency with depression is the reason for the robust positive correlation between depression and myocardial infarction. Patients with cardiovascular disease or Type II diabetes are often advised to adopt a low-fat diet with a high proportion of carbohydrate. A study with women shows that this type of diet increases plasma triglycerides and the severity of Type II diabetes and coronary heart disease. DHA is present in fatty fish (salmon, tuna, mackerel) and mother's milk. DHA is present at low levels in meat and eggs, but is not usually present in infant formulas. EPA, another long-chain n-3 fatty acid, is also present in fatty fish. The shorter chain n-3 fatty acid, alpha-linolenic acid, is not converted very well to DHA in man. These longchain n-3 fatty acids (also known as omega-3 fatty acids) are now becoming available in some foods, especially infant formula and eggs in Europe and Japan. Fish oil decreases the proliferation of tumour cells, whereas arachidonic acid, a longchain n-6 fatty acid, increases their proliferation. These opposite effects are also seen with inflammation, particularly with rheumatoid arthritis, and with asthma. DHA has a positive effect on diseases such as hypertension, arthritis, atherosclerosis, depression, adult-onset diabetes mellitus, myocardial infarction, thrombosis, and some cancers.     

The influence of orally administered docosahexaenoic acid on monoamine neurotransmitter,nerve growth factor,and brain-derived neurotrophic factor in aged mice

In this study we attempt to investigate the new role of docosahexaenoic acid (DHA) supplementation on cognitive ability in aged mice. Kunming-line mice were treated with DHA (200, 400?mg/kg body weight/day) for 30 successive days. The cognitive ability of mice was assessed by learning and memory behavioral test; the levels of DHA were assessed by capillary gas chromatography; the levels of dopamine (DA), norepinephrine (NE), and 5-hydroxytryptamine (5-HT) were assessed by high-performance liquid chromatography; the levels of brain-derived neurotrophic factor (BDNF) and nerve growth factor (NGF) proteins were assessed by the enzyme-linked immunosorbent assay method. The results showed the cognitive ability of mice were significantly different between the DHA-treated groups and the aged group, and orally administered DHA can increase the levels of DA, NE and 5-HT, the content of BDNF and NGF proteins in hippocampus, frontal cortex and striatum tissues. In addition, aged-related changes in phospholipid DHA content were seen. Decreases in DHA were mostly corrected by DHA supplementation. These novel data suggest that DHA supplementation can improve the cognitive dysfunction due to aging by increasing the levels of BDNF and NGF protein and the levels of DA, NE, 5-HT to some extent. We speculate that the mechanism of DHA on cognitive ability may have a beneficial effect on signaling networks through modulation of monoamine neurotransmitters and neurotrophic factors in brain aging.     

Omega 3-fatty acids: health benefits and cellular mechanisms of action

Epidemiological evidence has established that ingestion of long-chain polyunsaturated omega-3 fatty acids (omega-3 PUFAs), abundant in fish oils, have profound effects on many human disorders and diseases, including cardiovascular disease and cancer. Here we briefly review the dietary recommendations and the food sources that are naturally enriched by these fatty acids. There are also a number of products including eggs, bread, and cereals available to supplement omega-3 fatty acid dietary intake. Some of these supplements are proposed to aid different pathological conditions. While the beneficial effects of omega-3 fatty acids can no longer be doubted, their molecular mechanism of action remains elusive. Without question, the action of omega-3 fatty acids is complex and involves a number of integrated signaling pathways. This review focuses on one of the possible cellular mechanisms by which the omega-3 PUFAs, docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), may function. Studies with cancer cells suggest that DHA induces cell cycle arrest and apoptosis by activating protein phosphatases, leading to dephosphorylation of retinoblastoma protein (pRB). Protein phosphatases are also involved with the protein Bcl2, which regulates the release of cytochrome c from mitochondria, and eventually, activation of the apoptotic enzyme caspase 3.     

Oral administration of docosahexaenoic acid activates the GDNF-MAPK-CERB pathway in hippocampus of natural aged rat

Abstract

Context: Docosahexaenoic acid (DHA) is one of the critical fatty acids for optimal health, which affect the expression of nerve growth factor and brain-derived neurotrophic factor in brain.

Objective: This study investigates whether DHA supplementation affects lipid peroxidation and activates the glial-derived neurotrophic factor (GDNF)-mitogen-activated protein kinase pathway (MAPK pathway) in hippocampus of natural aged rat.

Materials and methods: Rats were randomly divided into four groups; DHA was orally administered at 80 and 160?mg/kg/day to 24-month female rats for 50 days. The antioxidant parameters and GDNF-GDNF family receptor α-1 (GFRα1)-tyrosine-protein kinase receptor (RET)-MAPK-cyclic AMP response element-binding protein (CERB) pathway were assayed in natural aged rat’s hippocampus.

Results and discussion: The results demonstrated that DHA supplementation significantly increased the activities of superoxide dismutase (SOD) by 37.39 and 57.69%, glutathione peroxidase (GSH-Px) by 27.62 and 32.57% decreased TBARS level by 28.49 and 49.05%, respectively, but did not significantly affect catalase (CAT), in hippocampus, when compared with the aged group. DHA supplementation in diet resulted in an increase of DHA level in hippocampus. Furthermore, we found that DHA supplementation markedly increased the levels of GDNF and GFRα1 and the phosphorylation of RET, and led to the activation of the MAPK pathway in hippocampus tissue.

Conclusion: DHA supplementation can change fatty acids composition, improve antioxidant parameters and activate the GDNF-MAPK pathway in natural aged rat’s hippocampus.     

A 3-week dietary bioequivalence study in preweaning farm piglets of two sources of docosahexaenoic acid produced from two different organisms

Docosahexaenoic acid (DHA) and arachidonic acid (ARA) are components of human breast milk and commonly added to infant formula. The first DHA-containing algal oil for infant formulas was DHASCO® produced from the microalgae Crypthecodinium cohnii. Recently, new DHA-rich oil was obtained from the microalgae Schizochytrium sp., herein named DHASCO-B. The objectives of this study were to evaluate the bioequivalence of DHASCO-B to DHASCO when administered in a blend with ARA oil and the potential effects after 3 weeks’ administration in milk replacer formula to preweaning farm piglets. DHASCO-B and DHASCO were added to formula at concentrations 0.32% and 0.96% DHA (% of total fatty acids). There were no test article-related effects of any diet on piglet growth and development (clinical observations, body weight, food consumption), or clinical pathology parameters (hematology, clinical chemistry, coagulation and urinalysis). In addition, there were no adverse effects at terminal necropsy (macro- and microscopic pathology evaluations). DHA content in plasma, RBC, heart, liver and brain showed dose-related accumulation and confirmed no differences between corresponding DHASCO-B and DHASCO groups. Therefore, dietary exposure to DHASCO-B and DHASCO was well tolerated by the preweaning piglets during the 3-week dosing period right after birth and DHASCO-B and DHASCO were bioequivalent.     

Differential responses to docosahexaenoic acid in primary and immortalized cardiac cells

The importance of dietary polyunsaturated fatty acids (PUFAs) in the reduction of cardiovascular disease has been recognized for many years. Docosahexaenoic acid (22:6n3, DHA) is an n-3 PUFA known to affect numerous biological functions and provide cardioprotection; however, the exact molecular and cellular protective mechanism(s) remain unknown. In contrast, DHA also possesses many anti-tumorgenic properties including suppressing cell growth and inducing apoptosis. In the present study, we investigated the effect of DHA toward H9c2 cells (an immortalized cardiac cell line) and neonatal primary cardiomyocytes (NCM). Cells were treated with 0 μM, 10 μM or 100 μM DHA for upto 48 h. Cell viability and mitochondrial activity were assayed at different time points. DHA caused a significant time- and dose-dependent decrease in cell viability and mitochondrial activity in H9c2 cells but not NCM. In addition, DHA decreased levels of TGF-β1 but increased IL-6 release in H9c2 cells. Significant induction of apoptosis was observed only in H9c2 cells, which involved activation of caspase-8 and -3 activities with a marked release of cytochrome c from mitochondria. DHA-induced severe mitochondrial damage resulting in a fragmented and punctated morphology with corresponding loss of mitochondrial membrane potential within 3 h, prior to activation of caspases and cytochrome c release at 6 h in H9c2 cells. Our data indicate that DHA treatment targets mitochondria, triggering collapse of mitochondrial membrane potential, increasing cellular stress and mitochondrial fragmentation resulting in apoptosis in immortalized cardiac cells, H9c2, but not neonatal primary cardiomyocyte.     

Cytochrome P450–dependent metabolism of ω-6 and ω-3 long-chain polyunsaturated fatty acids

Dietary fish oil ω-3 fatty acids (n-3 PUFAs), such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), protect against arrhythmia and sudden cardiac death using largely unknown mechanisms. EPA and DHA may serve as efficient alternative substrates of arachidonic acid (AA) metabolizing cytochrome P450 (CYP) enzymes. For many of the CYP isoforms, the n-3 PUFAs are the preferred substrates. Moreover, the CYP enzymes oxygenate EPA and DHA with largely different regioselectivities compared to AA. In particular, the ω-3 double bond that distinguishes EPA and DHA from AA is a preferred site of CYP-catalyzed epoxidation reactions. Given the pivotal role of CYP-dependent AA metabolites in the regulation of vascular, renal and cardiac functions, their replacement by unique sets of epoxy- and hydroxy-metabolites derived from EPA and DHA may have far-reaching physiological implications. The currently available data suggest that some of the vasculo- and cardioprotective effects attributed to dietary n-3 PUFAs may be mediated by CYP-dependent metabolites of EPA and DHA.     

多不饱和脂肪酸调血脂作用研究进展

多不饱和脂肪酸(Polyunsaturated fatty acids,PUFAs)是脂肪酸的一种,其碳链上有两个或两个以上双键。研究发现饮食脂肪酸对血脂代谢、冠心病(coronary heart disease,CHD)及动脉粥样硬化(atherosclerosis,AS)的发生有重要作用,尤其是PUFAs对血脂有正向调节作用,有利于降低心血管疾病发生的危险度系数。已有大量的文献对PUFAs的调血脂作用及其机制进行了探讨。     

Subchronic (13-week) oral toxicity study, preceded by an in utero exposure phase, with arachidonate-enriched triglyceride oil (SUNTGA40S) in rats.

Polyunsaturated fatty acids (PUFAs), such as arachidonic acid (ARA) and docosahexaenoic acid (DHA) are natural constituents found in human milk, fish oil or egg yolk. Until recently, infant formulas, though providing the essential fatty acid precursors for these PUFAs, did not contain preformed ARA or DHA. In this study the safety of SUNTGA40S as source of ARA, not only for use in infant formulas but also for nutritional products or food supplements, was evaluated in a subchronic study in Wistar rats, preceded by a 4-week pretreatment period of parental (F(0)) rats and exposure of the F(0) dams throughout mating, gestation and lactation. SUNTGA40S was administered at dietary levels of 0.5%, 1.5% and 5% (wt/wt) adjusted with corn oil to 5.76% added fat. An additional group received 3.65% (wt/wt) SUNTGA40S in conjunction with 2.11% (wt/wt) high DHA Tuna oil, providing an ARA:DHA ratio of 2.7:1. High-fat and low-fat controls received basal diet with or without 5.76% corn-oil supplement. The content, stability and homogeneous distribution of the test substances in the diet were confirmed under study conditions. The administration of SUNTGA40S, with or without DHA oil, did not affect health, growth, fertility or reproductive performance of the parental rats, nor pup characteristics (condition, weight gain, viability, number per litter or sex ratio). In the subchronic study with the offspring (F(1)) rats, no significant differences were found in condition, neurobehavioural observations, ophthalmoscopy, growth, urinalysis or macroscopic and microscopic findings between the test groups and the low-fat or the high-fat controls. In males of the 5% SUNTGA40S and the SUNTGA40S/DHA group, red blood cell counts, haemoglobin concentration and packed cell volume were lower and reticulocytes were slightly higher than in the high-fat and low-fat control groups. Cholesterol, triglycerides and phospholipids in plasma were lower than in the high-fat controls in both sexes in the 5% SUNTGA40S and the SUNTGA40S/DHA group and (for triglycerides only) in the 1.5% SUNTGA group. Due to the administration of extra dietary fat, food intake and prothrombin time (males only) were lower and alkaline phosphatase activity was higher in all the high-fat groups, including the corn-oil controls, as compared to the low-fat controls. The weight of the spleen was higher in males of the 5% SUNTGA40S and the SUNTGA40S/DHA group compared to both the low-fat and the high-fat controls. The effects noted in this study at high dose levels of SUNTGA40S are consistent with previously reported physiological responses to dietary intake of high PUFA containing oils. The present results provide evidence that SUNTGA40S is a safe source of arachidonic acid. Except during lactation when the intake in dams doubled, 5% Suntga40S in the diet was equivalent to an overall intake of approximately 3g/kg body weight/day in F(0) and F(1) animals.     

Docosahexaenoic acid and arachidonic acid release in rat brain astrocytes is mediated by two separate isoforms of phospholipase A2 and is differently regulated by cyclic AMP and Ca2+

1. Docosahexaenoic acid (DHA) and arachidonic acid (AA), polyunsaturated fatty acids (PUFAs), are important for central nervous system function during development and in various pathological states. Astrocytes are involved in the biosynthesis of PUFAs in neuronal tissue. Here, we investigated the mechanism of DHA and AA release in cultured rat brain astrocytes. 2. Primary astrocytes were cultured under standard conditions and prelabeled with [(14)C]DHA or with [(3)H]AA. Adenosine 5'-triphosphate (ATP) (20 micro M applied for 15 min), the P2Y receptor agonist, stimulates release of both DHA (289% of control) and AA (266% of control) from astrocytes. DHA release stimulated by ATP is mediated by Ca(2+)-independent phospholipase A(2) (iPLA(2)), since it is blocked by the selective iPLA(2) inhibitor 4-bromoenol lactone (BEL, 5 micro M) and is not affected either by removal of Ca(2+) from extracellular medium or by suppression of intracellular Ca(2+) release through PLC inhibitor (U73122, 5 micro M). 3. AA release, on the other hand, which is stimulated by ATP, is attributed to Ca(2+)-dependent cytosolic PLA(2) (cPLA(2)). AA release is abolished by U73122 and, by removal of extracellular Ca(2+), is insensitive to BEL and can be selectively suppressed by methyl arachidonyl fluorophosphonate (3 micro M), a general inhibitor of intracellular PLA(2) s. 4. Western blot analysis confirms the presence in rat brain astrocytes of 85 kDa cPLA(2) and 40 kDa protein reactive to iPLA(2) antibodies. 5. The influence of cAMP on regulation of PUFA release was investigated. Release of DHA is strongly amplified by the adenylyl cyclase activator forskolin (10 micro M), and by the protein kinase A (PKA) activator dibutyryl-cAMP (1 mM). In contrast, release of AA is not affected by forskolin or dibutyryl-cAMP, but is almost completely blocked by 2,3-dideoxyadenosine (20 micro M) and inhibited by 34% by H89 (10 micro M), inhibitors of adenylyl cyclase and PKA, respectively. 6. Other neuromediators, such as bradykinin, glutamate and thrombin, stimulate release of DHA and AA, which is comparable to the release stimulated by ATP. 7. Different sensitivities of iPLA(2) and cPLA(2) to Ca(2+) and cAMP reveal new pathways for the regulation of fatty acid release and reflect the significance of astrocytes in control of DHA and AA metabolism under normal and pathological conditions in brain.     

Evaluation of single-cell sources of docosahexaenoic acid and arachidonic acid: 3-month rat oral safety study with an in utero phase.

Owing to the presence of the polyunsaturated fatty acids (PUFA) docosahexaenoic acid (DHA) and arachidonic acid (ARA) in human milk and their important biological function, several authorities recommend that they be added to infant formulas. This study assessed the safety of an algal oil rich in DHA and a fungal oil rich in ARA, blended to provide a DHA to ARA ratio similar to human milk. The oil blend was incorporated into diets and fed to rats such that they received 3, 11 and 22 times the anticipated infant exposure to DHA and ARA. Low-fat and high-fat control groups received canola oil. Rats received experimental diets over a premating interval and throughout mating, gestation and lactation. Pups born during this period (F1) consumed treatment diets from weaning for 3 months. Physical observations, ophthalmoscopic examinations, body weight, food intake, clinical chemistry, neurobehavioural evaluations and postmortem histopathology of selected tissues were performed. No statistically significant, dose-dependent adverse effects were seen in reproductive performance or fertility, nor in the neonates from birth to weaning. Mid- and high-dose treated F1 animals exhibited increased white cell count, neutrophil count and blood urea nitrogen; increased liver and spleen weights (absolute and relative to body weight) also were observed. There were no corresponding microscopic findings. The clinical pathology and organ weight differences at these treatment levels represent physiological or metabolic responses to the test substance rather than adverse responses. These single-cell oils produced no adverse effects in rats when administered in utero and for 90 days at dietary levels resulting in exposures up to 22 or 66 times higher than those expected in infant formulas when extrapolated on the basis of diet composition (g/100 Cal) or intake (g/kg body weight), respectively.     

Do we need ‘new’ omega-3 polyunsaturated fatty acids formulations?

The therapeutic value of omega-3 polyunsaturated fatty acids (PUFAs), mainly (but not only) found in fish oils, eicosapentaenoic and docosahexaenoic acids (EPA and DHA, respectively), has been extensively studied in a wide variety of disease conditions, predominantly in cardiovascular disease. However, the significant difference in efficacy observed in various conditions with different dosages seems to be at least partly related to the large discrepancy in quality of the product and to the bioavailability of the omega-3 PUFA. The research of new sources (e.g., from arctic Krill oil) and pharmaceutical forms of omega-3 PUFA (e.g., omega-3 carboxylic acids) is needed in order to detect the one with the best bioavailability and efficacy, and with a parallel reduction in the production costs. There is also the need to understand if long-term PUFA supplementation could increase the efficacy of the already-available evidence–based therapies for cardiovascular disease prevention and for the management of the diseases where the use of PUFA could have a possible improving effect.     

Lipoic acid supplementation and endothelial function

Endothelial dysfunction is caused by all the recognized cardiovascular risk factors and has been implicated in the complex processes leading to the initiation and progression of atherosclerosis. Short-term treatment with lipoic acid is shown in the current issue of the British Journal of Pharmacology to improve endothelial function of aortic rings of old rats. The age-related decrease in phosphorylation of nitric oxide synthase and Akt was improved by lipoic acid supplementation. The improved phosphorylation status may have been due to reduced activity of the phosphatase PPA2, associated with decreased levels of endothelial ceramide induced by lipoic acid. Neutral sphingomyelinase activity was also reduced by lipoic acid, which was due, at least in part, to increased glutathione levels in endothelial cells. The favourable antioxidant, anti-inflammatory, metabolic and endothelial effects of lipoic acid shown in rodents, in this and other recently published studies, warrant further assessment of its potential role for prevention and treatment of cardiovascular diseases.