Omega-3 fatty acids deprivation affects ontogeny of glutamatergic synapses in rats: Relevance for behavior alterations

Essential omega-3 polyunsaturated fatty acids (ω3) are crucial to brain development and function, being relevant for behavioral performance. In the present study we examined the influence of dietary ω3 in the development of the glutamatergic system and on behavior parameters in rats. Female rats received isocaloric diets, either with ω3 (ω3 group) or a ω3 deficient diet (D group). In ontogeny experiments of their litters, hippocampal immunocontent of ionotropic NMDA and AMPA glutamatergic receptors subunits (NR2 A\B and GluR1, respectively) and the alpha isoform of the calcium-calmodulin protein kinase type II (αCaMKII) were evaluated. Additionally, hippocampal [³H]glutamate binding and uptake were assessed. Behavioral performance was evaluated when the litters were adult (60 days old), through the open-field, plus-maze, inhibitory avoidance and flinch-jump tasks. The D group showed decreased immunocontent of all proteins analyzed at 02 days of life (P2) in comparison with the ω3 group, although the difference disappeared at 21 days of life (except for αCaMKII, which content normalized at 60 days old). The same pattern was found for [³H]glutamate binding, whereas [³H]glutamate uptake was not affected. The D group also showed memory deficits in the inhibitory avoidance, increased in the exploratory pattern in open-field, and anxiety-like behavior in plus-maze. Taken together, our results suggest that dietary ω3 content is relevant for glutamatergic system development and for behavioral performance in adulthood. The putative correlation among the neurochemical and behavioral alterations caused by dietary ω3 deficiency is discussed.     

Changes in the Properties of Glutamatergic Synapses in the Medial Prefrontal Cortex and Nucl. Accumbens in Rats with Behavioral Depression

In experiments on surviving rat forebrain slices, we studied the characteristics of glutamatergic synaptic transmission in the medial prefrontal cortex (MPFC) and nucl. accumbens. It was found that in rats with behavioral depression induced by zoosocial isolation (72 h), the mean amplitude of field EPSP (fEPSP) in the MPFC demonstrated no significant alterations. At the same time, the developments of rhythmic stimulation-caused long-term potentiation (LTP) and long-term depression (LTD) of synaptic transmission were suppressed, as compared with the control. In the nucl. accumbens of rats with behavioral depression, the mean fEPSP amplitude increased by nearly 25%, whereas rhythmic stimulation-induced LTD of transmission through synaptic connections between the cortex and nucl. accumbens weakened. Changes in the relay and plastic properties of glutamatergic synapses typical of behavioral depression were reproduced under conditions of chronic (for 3 days) i.p. injections of 1 mg/kg dexamethasone into the experimental animals. The influences exerted on brain slices in vitro by a synthetic glucocorticoid, dexamethasone, and a mineralocorticoid, deoxycorticosterone acetate, applied over 2 h in concentrations of 100 nM, did not significantly affect glutamatergic synaptic transmission in the MPFC and nucl. accumbens. In brain slices from animals with behavioral depression or from those subjected to chronic injection of dexamethasone, we observed a reduction of the modulatory effect of dexamethasone and a nonselective agonist of dopamine receptors, apomorphine hydrochloride, on glutamatergic synaptic transmission in the MPFC and nucl. accumbens. This is considered an indirect reflection of a decrease in the efficiency (down-regulation) of glucocorticoid and dopamine receptors in neurons of the brain structures under study. It is hypothesized that changes in the main properties of glutamatergic synapses in the forebrain structures (MPFC and nucl. accumbens), which were observed under conditions of behavioral depression, are determined by both direct effects of glucocorticoids on cortical and mesolimbic neurons and indirect effects mediated by the cerebral dopaminergic system.     

Fatty acid content of the dorsal muscle—an indicator of fat quality in freshwater fish

In 56 samples of freshwater fish, most were low in fat, ≤ 5% of dry weight (D.W.), and the sum of all fatty acids (ΣFA) was about 2% of D.W. Trout, whitefish, and grayling had the highest content of the long-chained FA. of ω3 type, EPA and DHA (1·7–2·6% of D.W.). Two large, low-fat pikes with ΣFA of about12–3% of D.W. and a medium-fat whitefish had the highest ω3/ω6 ratios, 8–9, whereas the fattiest fishes, eels from two lakes and the Baltic (ΣFA =17–26% of D.W.) had lower ω3/ω6 ratios, 1·1–1·8 (ω3 and ω6 FA are two important series of FA). The results indicate that ΣA controls the content of saturated FA (SAFA) and monounsaturated FA (MUFA), whereas the polyunsaturated FA (PUFA) was independent of ΣFA after a break point of about 10%ΣFA of D.W. The P/S ratio (PUFA/SAFA) and the PUFA/ΣFA ratio decreased with increased ΣFA, whereas the ω3/ω6 ratio showed no clear correlation to ΣFA. The difference in fatty acid patterns lay between low-fat and high-fat fishes, rather than between marine and freshwater fishes. The variation, both within and between species of the separate FA is small in fish with similar ΣFA content. Also, low-fat and medium-fat fishes tend to be more dietarily favourable than high-fat fishes, when considering the latest criteria for high nutritional value to humans. Abbreviations used in the text: FA, fatty acids; ΣFA, sum of all FA; AA, arachidonic acid (20 : 4ω6); EPA, eicosapentaenoic acid (20 : 5ω3); DHA, docosahexaenoic acid (22 : 6ω3); SAFA, saturated fatty acids; MUFA, monounsaturated fatty acids; PUFA, polyunsaturated fatty acids; D.W., dry weight; F.W. fresh weight; CV, coefficient of variation; ω3 FA, series of PUFA with the first double bond located at carbon number 3; ω6 FA, series of PUFA with the first double bond located at carbon number 6. The fatty acids are described by three numbers, x:ywz, where x=number of carbon atoms, y=number of double bonds, and z=position of the first double bond counted from the methyl end of the molecule.     

Contrasting effects of arachidonic acid and docosahexaenoic acid membrane incorporation into cardiomyocytes on free cholesterol turnover

The preservation of a constant pool of free cholesterol (FC) is critical to ensure several functions of cardiomyocytes. We investigated the impact of the membrane incorporation of arachidonic acid (C20:4 ω6, AA) or docosahexaenoic acid (C22:6 ω3, DHA) as ω6 or ω3 polyunsaturated fatty acids (PUFAs) on cholesterol homeostasis in primary cultures of neonatal rat cardiac myocytes. We measured significant alterations to the phospholipid FA profiles, which had markedly different ω6/ω3 ratios between the AA and DHA cells (13 vs. 1). The AA cells showed a 2.7-fold lower cholesterol biosynthesis than the DHA cells. Overall, the AA cells showed 2-fold lower FC masses and 2-fold higher cholesteryl ester masses than the DHA cells. The AA cells had a lower FC to phospholipid ratio and higher triglyceride levels than the DHA cells. Moreover, the AA cells showed a 40% decrease in ATP binding cassette transporter A1 (ABCA1)-mediated and a 19% decrease in ABCG1-mediated cholesterol efflux than the DHA cells. The differences in cholesterol efflux pathways induced by AA or DHA incorporation were not caused by variations in ABCs transporter expression and were reduced when ABC transporters were overexpressed by exposure to LXR/RXR agonists. These results show that AA incorporation into cardiomyocyte membranes decreased the FC turnover by markedly decreasing the endogenous cholesterol synthesis and by decreasing the ABCA1- and ABCG1-cholesterol efflux pathways, whereas DHA had the opposite effects. We propose that these observations may partially contribute to the beneficial effects on the heart of a diet containing a high ω3/ω6 PUFA ratio.     

The importance of highly unsaturated fatty acids in zooplankton nutrition: evidence from experiments with Daphnia, a cyanobacterium and lipid emulsions

1. We used laboratory growth and feeding experiments to evaluate the role of ω3 highly unsaturated fatty acids (HUFA) in zooplankton nutrition. Polyunsaturated fatty acids (PUFA) comprised 40% of total fatty acids (FA) in the green alga Scenedesmus acutus but only 6% in the cyanobacterium Synechococcus elongatus.Scenedesmus contained modest amounts of the ω3 HUFA eicosapentaenoic acid (EPA, 20 : 5ω3) and docosahexaenoic acid (DHA, 22 : 6ω3), whereas Synechococcus contained only a trace of EPA and no DHA. 2. One-day-old Daphnia maintained high growth rates for 2–3 days on a diet of Synechococcus but exhibited reduced growth or even lost weight over the later part of the 6- or 7-day experiments. Daphnia magna grew better than D. galeata or D. pulicaria on a diet of pure Synechococcus. Daphnids fed the same concentration (0.5 mgC l^–1) of green algae or a mixture of green algae and Synechococcus maintained high growth rates. 3. Supplementing Synechococcus with fish oil emulsions rich in ω3 HUFA markedly improved the growth and reproduction of all three Daphnia species. Supplementation with an emulsion of monounsaturated oleic acid (18 : 1ω9), however, did not affect the growth of D. galeata and caused a decrease in the growth of D. magna. 4. Short-term (7 min) and long-term (3 h) feeding trials with ¹⁴C-labelled Synechococcus were used to evaluate the effects of acclimation and mixed diets on carbon incorporation. D. galeata that had fed on unlabelled Synechococcus for 3 days exhibited no decline in clearance rate but a marked decline in carbon incorporation in comparison with animals acclimated with Scenedesmus or fed a mixture of Synechococcus and Scenedesmus. 5. Our results support the hypothesis that the poor nutritional quality of a cyanobacterium is at least partially due to a HUFA deficiency. Growth and feeding experiments both suggest that the utilization of Synechococcus is enhanced by HUFA from lipid reserves or a mixed diet.     

Gestational age dependent changes of the fetal brain, liver and adipose tissue fatty acid compositions in a population with high fish intakes

IntroductionThere are no data on the intrauterine fatty acid (FA) compositions of brain, liver and adipose tissue of infants born to women with high fish intakes.Subjects and methodsWe analyzed the brain (n=18), liver (n=14) and adipose tissue (n=11) FA compositions of 20 stillborn infants with different gestational ages (range 8–38 weeks) born to Tanzanian women with low linoleic acid (LA) intakes and high intakes of docosahexaenoic (DHA) and arachidonic (AA) acids from local fish.Results and discussionWith advancing gestation, brain saturated-FA (SAFA; in g/100 g FA), polyunsaturated-FA (PUFA), DHA, 20:3ω6, 22:4ω6 and 22:5ω6 increased, while monounsaturated-FA (MUFA), 20:3ω9, 22:3ω9 and AA decreased. Decreasing brain AA might be caused by increasing AA-metabolism to 20:3ω6, 22:4ω6 and 22:5ω6. In the liver, SAFA, PUFA and LA increased, while MUFA decreased with gestation. The steep increase of (mostly de novo synthesized) SAFA in adipose tissue coincided with relative decreases of MUFA, PUFA, DHA, LA and AA with advancing gestation. Compared to Western infants, the currently studied African infants had higher DHA, lower AA, and a higher DHA/AA-ratio in brain and adipose tissue, while the LA content of adipose tissue was lower.ConclusionThe low LA and high DHA and AA intakes by the mothers of these infants might support optimal α-linolenic (ALA) vs. LA competition for Δ5D and Δ6D-activities and DHA vs. AA antagonism. Conversely, the Western diet, characterized by high LA and lower DHA and AA intakes, might disturb these evolutionary conserved mechanisms aiming at an optimal ω3/ω6-balance.     

Intrapopulation variability in a functional trait: Susceptibility of Daphnia to limitation by dietary fatty acids

1. Functional traits are measurable characteristics of an organism that have an impact on its fitness. Variation in functional traits between and among species has been suggested to represent the basis for competition and selection, thus allowing for evolution in natural populations.
2. In freshwater ecosystems, the availability of essential polyunsaturated fatty acids (PUFAs), in particular ω3‐ and ω6‐PUFAs, determines the food quality of phytoplankton for the herbivorous zooplankton Daphnia, an unselective filter feeder. The content of such essential PUFAs in the phytoplankton is thus a functional phytoplankton trait affecting the trophic transfer efficiency and dynamics at the pelagic plant–herbivore interface.
3. In turn, the susceptibility of consumers to become limited by the availability of essential PUFAs is a fitness‐determining trait of Daphnia genotypes, and variability of this herbivore trait may thus affect the daphnids’ intrapopulation competition. To estimate the intrapopulation variation in susceptibility, we isolated clonal lines of Daphnia longispina from a natural population and compared the strength of their limitation by dietary PUFA availability via standardised laboratory growth assays. We used a liposome supplementation technique to enrich a PUFA‐poor green alga with essential ω3‐ and ω6‐PUFAs and determined juvenile somatic growth rate of different D. longispina genotypes as a fitness proxy.
4. As expected, D. longispina genotypes that coexisted in a natural population differed markedly in their specific patterns of susceptibility to dietary PUFA availability. On average, the D. longispina population was more strongly susceptible to limitations in the availability of the ω6‐PUFA arachidonic acid (20:4ω6) than to limitations in the availability of ω3‐PUFAs α‐linolenic acid (18:3ω3) and eicosapentaenoic acid (20:5ω3).
5. The ability to cope with PUFA limitation is thus a crucial trait that can probably affect intraspecific competition and Daphnia population structure. Therefore, we suggest that such intrapopulation variation in susceptibility to absence of dietary PUFAs might be one of the driving forces of natural selection and local adaptation among freshwater zooplankton.

     

Methyl-end desaturases with ∆12 and ω3 regioselectivities enable the de novo PUFA biosynthesis in the cephalopod Octopus vulgaris

The interest in understanding the capacity of aquatic invertebrates to biosynthesise omega-3 (ω3) long-chain (≥C₂₀) polyunsaturated fatty acids (LC-PUFA) has increased in recent years. Using the common octopus Octopus vulgaris as a model species, we previously characterised a ∆5 desaturase and two elongases (i.e. Elovl2/5 and Elovl4) involved in the biosynthesis of LC-PUFA in molluscs. The aim of this study was to characterise both molecularly and functionally, two methyl-end (or ωx) desaturases that have been long regarded to be absent in most animals. O. vulgaris possess two ωx desaturase genes encoding enzymes with ∆12 and ω3 regioselectivities enabling the de novo biosynthesis of the C₁₈ PUFA 18:2ω6 (LA, linoleic acid) and 18:3ω3 (ALA, α-linolenic acid), generally regarded as dietary essential for animals. The O. vulgaris ∆12 desaturase (“ωx2”) mediates the conversion of 18:1ω9 (oleic acid) into LA, and subsequently, the ω3 desaturase (“ωx1”) catalyses the ∆15 desaturation from LA to ALA. Additionally, the O. vulgaris ω3 desaturase has ∆17 capacity towards a variety of C₂₀ ω6 PUFA that are converted to their ω3 PUFA products. Particularly relevant was the affinity of the ω3 desaturase towards 20:4ω6 (ARA, arachidonic acid) to produce 20:5ω3 (EPA, eicosapentaenoic acid), as supported by yeast heterologous expression, and enzymatic activity exhibited in vivo when paralarvae were incubated in the presence of [1-¹⁴C]20:4ω6. These results confirmed that several routes enabling EPA biosynthesis are operative in O. vulgaris whereas ARA and docosahexaenoic acid (DHA, 22:6ω3) should be considered essential fatty acids since endogenous production appears to be limited.     

Inhibition of astroglial glutamate transport by polyunsaturated fatty acids: Evidence for a signalling role of docosahexaenoic acid

Brain cells are especially rich in polyunsaturated fatty acids (PUFA), mainly the n-3 PUFA docosahexaenoic acid (DHA) and the n-6 PUFA arachidonic acid (AA). They are released from membranes by PLA2 during neurotransmission, and may regulate glutamate uptake by astroglia, involved in controlling glutamatergic transmission. AA has been shown to inhibit glutamate transport in several model systems, but the contribution of DHA is less clear and has not been evaluated in astrocytes. Because the high DHA content of brain membranes is essential for brain function, we investigated the role of DHA in the regulation of astroglial glutamate transport.We evaluated the actions of DHA and AA using cultured rat astrocytes and suspensions of rat brain membranes (P1 fractions). DHA reduced d-[³H]aspartate uptake by cultured astrocytes and cortical membrane suspensions, while AA did not. This also occurred in astrocytes enriched with α-tocopherol, indicating that it was not due to peroxidation products. The reduction of d-[³H]aspartate uptake by DHA did not involve any change in the concentrations of membrane-associated astroglial glutamate transporters (GLAST and GLT-1), suggesting that DHA reduced the activity of the transporters. In contrast with the inhibition induced by free-DHA, we found no effect of membrane-bound DHA on d-[³H]aspartate uptake. Indeed, the uptake was similar in astrocytes with varying amount of DHA in their membrane (induced by long-term supplementation with DHA or AA). Therefore, DHA reduces glutamate uptake through a signal-like effect but not through changes in the PUFA composition of the astrocyte membranes. Also, reactive astrocytes, induced by a medium supplement (G5), were insensitive to DHA. This suggests that DHA regulates synaptic glutamate under basal condition but does not impair glutamate scavenging under reactive conditions.These results indicate that DHA slows astroglial glutamate transport via a specific signal-like effect, and may thus be a physiological synaptic regulator.     

Effects of dietary omega-3 PUFAs on growth and development: Somatic,neurobiological and reproductive functions in a murine model

Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) are relevant to fetal and infant growth and development. Objective: to assess whether long-term exposure to dietary ω-3 PUFA imbalance alters pre- and/or postnatal pups' development and reproductive function later in life. Mice dams were fed with ω-3 PUFA Control (soybean oil, 7%), Deficient (sunflower oil, 7%) or Excess (blend oil; 4.2% cod-liver+2.8% soybean) diet before conception and throughout gestation-lactation and later on, their pups received the same diet from weaning to adulthood. Offspring somatic, neurobiological and reproductive parameters were evaluated. Excess pups were lighter during the preweaning period and shorter in length from postnatal day (PND) 7 to 49, compared to Control pups (P<.05). On PND14, the percentage of pups with eye opening in Excess group was lower than those from Control and Deficient groups (P<.05). In Excess female offspring, puberty onset (vaginal opening and first estrus) occurred significantly later and the percentage of parthenogenetic oocytes on PND63 was higher than Control and Deficient ones (P<.05). Deficient pups were shorter in length (males: on PND14, 21, 35 and 49; females: on PND14, 21 and 42) compared with Control pups (P<.05). Deficient offspring exhibited higher percentage of bending spermatozoa compared to Control and Excess offspring (P<.05). These results show that either an excessively high or insufficient ω-3 PUFA consumption prior to conception until adulthood seems inadvisable because of the potential risks of short-term adverse effects on growth and development of the progeny or long-lasting effects on their reproductive maturation and function.     

Aging-Associated Changes in the Pharmacological Properties of the Benzodiazepine (ω) Receptor Isotypes in the Rat Hippocampus

Abstract: The aging-associated changes in hippocampal benzodiazepine (ω) receptor isotypes have been investigated in rats of the Wistar and Fischer 344 strains. Displacement experiments of [³H]flunitrazepam binding by zolpidem demonstrated that in hippocampal membranes from adult (3-month-old) Wistar strain rats, high (type I; ω₁)-, intermediate (type II_M; ω₂)-, and low (type II_L; ω₅)- affinity sites for this imidazopyridine account for 27.1 ± 7.5, 44.2 ± 7.5, and 28.8 ± 5.1%, respectively. In hippocampal membranes from aged (24-month-old) rats of the same strain, the relative abundance of these sites was 42.8 ± 9.3, 26.3 ± 4, and 36.0 ± 5.9%, respectively. In contrast, no significant difference was observed in the whole benzodiazepine (ω) binding site density between adult and aged rats. The increase in type I (ω₁) binding site density in the hippocampus of aged rats was also demonstrated in saturation experiments with [³H]zolpidem. This aging-induced increase in [³H]zolpidem binding was also observed in hippocampal membranes from Fischer 344 rats. Moreover, in both rat strains, GABA induced a greater enhancement of [³H]zolpidem (5 nM) binding to type I (ω₁) sites (GABA shift) in aged than in adult hippocampal membranes. Quantitative autoradiographic analysis of [³H]zolpidem binding to coronal brain sections from adult and aged Fischer 344 rats demonstrated that the aging-associated increases in the density of type I (ω₁) binding sites were restricted to the hippocampus. Moreover, increases in binding density were larger in the dentate gyrus and in the CA2 field than in the CA1 and CA3 fields.     

Chemical synthesis and biological evaluation of ω-hydroxy polyunsaturated fatty acids

ω-Hydroxy polyunsaturated fatty acids (PUFAs), natural metabolites from arachidonic acid (ARA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) were prepared via convergent synthesis approach using two key steps: Cu-mediated CC bond formation to construct methylene skipped poly-ynes and a partial alkyne hydrogenation where the presence of excess 2-methyl-2-butene as an additive that is proven to be critical for the success of partial reduction of the poly-ynes to the corresponding cis-alkenes without over-hydrogenation. The potential biological function of ω-hydroxy PUFAs in pain was evaluated in naive rats. Following intraplantar injection, 20-hydroxyeicosatetraenoic acid (20-HETE, ω-hydroxy ARA) generated an acute decrease in paw withdrawal thresholds in a mechanical nociceptive assay indicating pain, but no change was observed from rats which received either 20-hydroxyeicosapentaenoic acid (20-HEPE, ω-hydroxy EPA) or 22-hydroxydocosahexaenoic acid (22-HDoHE, ω-hydroxy DHA). We also found that both 20-HEPE and 22-HDoHE are more potent than 20-HETE to activate murine transient receptor potential vanilloid receptor1 (mTRPV1).     

Polyunsaturated ω3 fatty acids prevent the cardiac hypertrophy in hypertensive rats

It has been demonstrated that supplementation with the two main omega 3 polyunsaturated fatty acids (ω3 FAs), docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), leads to modifications in the cardiac physiology. ω3 FAs can affect the membrane's lipid composition, as well as proteins' location and/or function. The Na⁺/H⁺ exchanger (NHE1) is an integral membrane protein involved in the maintenance of intracellular pH and its hyperactivity has been associated with the development of various cardiovascular diseases such as cardiac hypertrophy.Our aim was to determine the effect of ω3 FAs on systolic blood pressure (SBP), lipid profiles, NHE1 activity, and cardiac function in spontaneously hypertensive rats (SHR) using Wistar rats (W) as normotensive control. After weaning, the rats received orally ω3 FAs (200 mg/kg body mass/day/ 4 months). We measured SBP, lipid profiles, and different echocardiography parameters, which were used to calculate cardiac hypertrophy index, systolic function, and ventricular geometry. The rats were sacrificed, and ventricular cardiomyocytes were obtained to measure NHE1 activity.While the treatment with ω3 FAs did not affect the SBP, lipid analysis of plasma revealed a significant decrease in omega-6/omega-3 ratio, correlated with a significant reduction in left ventricular mass index in SHR.The NHE1 activity was significantly higher in SHR compared with W. While in W the NHE1 activity was similar in both groups, a significant decrease in NHE1 activity was detected in SHRs supplemented with ω3 FAs, reaching values comparable with W. Altogether, these findings revealed that diet supplementation with ω3 FAs since early age prevents the development of cardiac hypertrophy in SHR, perhaps by decreasing NHE1 activity, without altering hemodynamic overload.     

Microglial and astroglial activation by 3,4‐methylenedioxymethamphetamine (MDMA) in mice depends on S(+) enantiomer and is associated with an increase in body temperature and motility

Evidence is accumulating to suggest that 3,4‐methylenedioxymethamphetamine (MDMA) has neurotoxic and neuroinflammatory properties. MDMA is composed of two enantiomers with different biological activities. In this study, we evaluated the in vivo effects of S(+)‐MDMA, R(?)‐MDMA, and S(+)‐MDMA in combination with R(?)‐MDMA on microglial and astroglial activation compared with racemic MDMA, by assessment of complement type 3 receptor (CD11b) and glial fibrillary acidic protein (GFAP) immunoreactivity in the mouse striatum, nucleus accumbens, motor cortex, and substantia nigra. Motor activity and body temperature were also measured, to elucidate the physiological modifications paired with the observed glial changes. Similar to racemic MDMA (4 × 20 mg/kg), S(+)‐MDMA (4 × 10 mg/kg) increased both CD11b and GFAP in the striatum, although to a lower degree, whereas R(?)‐MDMA (4 × 10 mg/kg) did not induce any significant glial activation. Combined administration of S(+) plus R(?)‐MDMA did not induce any further activation compared with S(+)‐MDMA. In all other areas, only racemic MDMA was able to slightly activate the microglia, but not the astroglia, whereas enantiomers had no effect, either alone or in combination. Racemic MDMA and S(+)‐MDMA similarly increased motor activity and raised body temperature, whereas R(?)‐MDMA affected neither body temperature nor motor activity. Interestingly, the increase in body temperature was correlated with glial activation. The results show that no synergism, but only additivity of effects, is caused by the combined administration of S(+)‐ and R(?)‐MDMA, and underline the importance of investigating the biochemical and behavioral properties of the two MDMA enantiomers to understand their relative contribution to the neuroinflammatory and neurotoxic effects of MDMA.     

Omega-3 polyunsaturated fatty acid has an anti-oxidant effect via the Nrf-2/HO-1 pathway in 3T3-L1 adipocytes

Oxidative stress is produced in adipose tissue of obese subjects and has been associated with obesity-related disorders. Recent studies have shown that omega-3 polyunsaturated fatty acid (ω3-PUFA) has beneficial effects in preventing atherosclerotic diseases and insulin resistance in adipose tissue. However, the role of ω3-PUFA on adipocytes has not been elucidated. In this study, 3T3-L1 adipocytes were treated with ω3-PUFA and its metabolites, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), or 4-hydroxy hexenal (4-HHE). ω3-PUFA and its metabolites dose-dependently increased mRNA and protein levels of the anti-oxidative enzyme, heme oxygenase-1 (HO-1); whereas no changes in the well-known anti-oxidant molecules, superoxide dismutase, catalase, and glutathione peroxidase, were observed. Knockdown of nuclear factor erythroid 2-related factor 2 (Nrf-2) significantly reduced EPA, DHA or 4-HHE-induced HO-1 mRNA and protein expression. Also, pretreatment with ω3-PUFA prevented H₂O₂-induced cytotoxicity in a HO-1 dependent manner. In conclusion, treatment with EPA and DHA induced HO-1 through the activation of Nrf-2 and prevented oxidative stress in 3T3-L1 adipocytes. This anti-oxidant defense may be of high therapeutic value for clinical conditions associated with systemic oxidative stress.     

Different fermentation strategies by Schizochytrium mangrovei strain pq6 to produce feedstock for exploitation of squalene and omega‐3 fatty acids

Schizochytrium mangrovei strain PQ 6 was investigated for coproduction of docosahexaenoic acid (C22: 6ω‐3, DHA ) and squalene using a 30‐L bioreactor with a working volume of 15 L under various batch and fed‐batch fermentation process regimes. The fed‐batch process was a more efficient cultivation strategy for achieving higher biomass production rich in DHA and squalene. The final biomass, total lipid, unsaponifiable lipid content, and DHA productivity were 105.25 g · L^?1, 43.40% of dry cell weight, 8.58% total lipid, and 61.66 mg · g^?1 · L^?1, respectively, after a 96 h fed‐batch fermentation. The squalene content was highest at 48 h after feeding glucose (98.07 mg · g^?1 of lipid). Differences in lipid accumulation during fermentation were correlated with changes in ultrastructure using transmission electron microscopy and Nile Red staining of cells. The results may be of relevance to industrial‐scale coproduction of DHA and squalene in heterotrophic marine microalgae such as Schizochytrium .     

Strain variability in fatty acid composition of Chattonella marina (Raphidophyceae) and its relation to differing ichthyotoxicity toward rainbow trout gill cells

Lipid profiles of three strains (Mexico, Australia, Japan) of Chattonella marina (Subrahmanyan) Hara et Chihara were studied under defined growth (phosphate, light, and growth phase) and harvest (intact and ruptured cells) conditions. Triacylglycerol levels were always <2%, sterols <7%, free fatty acids varied between 2 and 33%, and polar lipids were the most abundant lipid class (>51% of total lipids). The major fatty acids in C. marina were palmitic (16:0), eicosapentaenoic (EPA, 20:5ω3), octadecatetraenoic (18:4ω3), myristic (14:0), and palmitoleic (16:1ω7c) acids. Higher levels of EPA were found in ruptured cells (21.4–29.4%) compared to intact cells (8.5–25.3%). In general, Japanese N‐118 C. marina was the highest producer of EPA (14.3–29.4%), and Mexican CMCV‐1 the lowest producer (7.9–27.1%). Algal cultures, free fatty acids from C. marina, and the two aldehydes 2E,4E‐decadienal and 2E,4E‐heptadienal (suspected fatty acid‐derived products) were tested against the rainbow trout fish gill cell line RTgill‐W1. The configuration of fatty acids plays an important role in ichthyotoxicity. Free fatty acid fractions, obtained by base saponification of total lipids from C. marina showed a potent toxicity toward gill cells (median lethal concentration, LC₅₀ (at 1 h) of 0.44 μg · mL^?1 in light conditions, with a complete loss of viability at >3.2 μg · mL^?1). Live cultures of Mexican C. marina were less toxic than Japanese and Australian strains. This difference could be related to differing EPA content, superoxide anion production, and cell fragility. The aldehydes 2E,4E‐decadienal and 2E,4E‐heptadienal also showed high impact on gill cell viability, with LC₅₀ (at 1 h) of 0.34 and 0.36 μg · mL^?1, respectively. Superoxide anion production was highest in Australian strain CMPL01, followed by Japanese N‐118 and Mexican CMCV‐1 strains. Ruptured cells showed higher production of superoxide anion compared to intact cells (e.g., 19 vs. 9.5 pmol · cell^?1 · hr^?1 for CMPL01, respectively). Our results indicate that C. marina is more ichthyotoxic after cell disruption and when switching from dark to light conditions, possibly associated with a higher production of superoxide anion and EPA, which may be quickly oxidized to produce more toxic derivates, such as aldehydes.     

Plasma and red blood cell total phospholipid fatty acid status of nonpregnant female Vervet monkeys (Cercopithecus aethiops) on a high carbohydrate maintenance diet

Nonhuman primates are of interest as models of human physiology to study the effect of multiple pregnancies on birth weight. Reference plasma and red blood cell (RBC) total phospholipids fatty acids were established in nonpregnant breeding female Vervet monkeys. Twenty-three clinically healthy nonpregnant Vervet monkeys (Cercopithecus aethiops), contained in a controlled closed environment and consuming a high carbohydrate diet (68 E%) that contained 20 E% fat and 12 E% protein were sampled for blood during a cross-sectional study. A low intake of ω3 fatty acids was reflected by a high ω6/ω3 ratio (66:1) of the diet. Inverse relations were seen between plasma and RBC total phospholipid fatty acids, 18:2ω6, 20:3ω6, and 20:4ω6, which suggested selective incorporation in membranes. Low levels of 20:5ω3 and 22:6ω3 of plasma and RBC total phospholipids render Vervet monkeys as ideal subjects to study the effect of ω3 fatty acid supplementation on pregnancy outcomes. Tichelaar HY, van Jaarsveld PJ, Smuts CM, Marais M, Mdhluli MC, Kruger M, Benadé AJS. Plasma and red blood cell total phospholipid fatty acid status of nonpregnant female Vervet monkeys (Cercopithecus aethiops) on a high carbohydrate maintenance diet. J Med Primatol 1998; 27:240–243. © Munksgaard, Copenhagen     

Effects of ω3 Polyunsaturated Fatty Acids on Growth and Tissue Fatty Acid Compositions of Maternal Rats and Their Progeny

The effects of ω3 polyunsaturated fatty acids [PUFA; mainly eicosapentaenoic acid (20: 5, ω3) and docosahexaenoic acid (22:6, ω3)] on the growth, tissue weights and fatty acid compositions of tissue total lipids in female rats and their progeny were investigated. Female rats of the Wistar strain, weighing 77~94g, were fed a 25% casein diet containing 5% of either corn oil (control), sardine oil or PUFA ethyl ester for 8 ~ 9 weeks prior to mating, and during gestation and lactation, and then for a further 2 weeks. The progeny were weaned to the maternal diet and then the latter was administered for a further 2 weeks. Dietary changes in the body weights of the dams were not generally seen, but the body weights at birth and growth of the offspring from the females supplied with the PUFA diet were inferior compared to those of the other groups. The fertility did not differ among the dietary groups. The weights of several tissues in the dams and the progeny increased in proportion to their body weights but not that of the progeny brain, which remained ' almost unchanged by the dietary fats. As to the fatty acid compositions of total lipids in the tissues, on the whole, decreased levels of ωβ fatty acids and increased percentages of ω3 fatty acids were found in the sardine and PUFA groups, the changes being greater in the PUFA group than in the sardine one. Such findings due to the feeding of PUFA were more remarkable in the progeny compared with in the dams. Eicosatrienoic acid (20: 3, ω9) was almost completely undetectable in the tissue total lipids of all the dietary groups.