Enrichment of brain docosahexaenoic acid (DHA) is highly dependent upon the molecular carrier of dietary DHA: lysophosphatidylcholine is more efficient than either phosphatidylcholine or triacylglycerol.

Docosahexaenoic acid (DHA) is highly concentrated in the brain, and its deficiency is associated with several neurological disorders including Alzheimer's disease. However, the currently used supplements do not appreciably enrich brain DHA, although they enrich most other tissues. We tested the hypothesis that the ability of the dietary carrier to augment brain DHA depends upon the generation of DHA-lysophosphatidylcholine (LPC), the preferred carrier of DHA across the blood brain barrier. We compared the efficacy of DHA-triacylglycerol (TAG), di-DHA phosphatidylcholine (PC) and DHA-LPC to enrich brain DHA following their gavage to normal rats for 30 days, all at a dose of 10 mg DHA/day. The results show that DHA from TAG, which is released as free DHA or monoacylglycerol during digestion and is absorbed as TAG in chylomicrons, was incorporated preferentially into adipose tissue and heart but not into brain. In contrast, LPC-DHA increased brain DHA by up to 100% but had no effect on adipose tissue. Di-DHA PC, which generates both free DHA and LPC-DHA during the digestion, enriched DHA in brain, as well as in heart and liver. Brain-derived neurotrophic factor was increased by di-DHA PC and DHA-LPC, but not by TAG-DHA, showing that enrichment of brain DHA correlated with its functional effect. We conclude that dietary DHA from TAG or from natural PC (sn-2 position) is not suitable for brain enrichment, whereas DHA from LPC (at either sn-1 or sn-2 position) or from sn-1 position of PC efficiently enriches the brain and is functionally effective.

Metabolism of uniformly labeled 13C-eicosapentaenoic acid and 13C-arachidonic acid in young and old men.

Background: Plasma eicosapentaenoic acid (EPA) and arachidonic acid (AA) concentrations increase with age.Objective: The aim of this study was to evaluate EPA and AA metabolism in young and old men by using uniformly labeled carbon-13 (13C) fatty acids.Design: Six young (∼25 y old) and 6 old (∼75 y old) healthy men were recruited. Each participant consumed a single oral dose of 35 mg 13C-EPA and its metabolism was followed in the course of 14 d in the plasma and 28 d in the breath. After the washout period of ≥28 d, the same participants consumed a single oral dose of 50 mg 13C-AA and its metabolism was followed for 28 d in plasma and breath.Results: There was a time × age interaction for 13C-EPA (Ptime × age = 0.008), and the shape of the postprandial curves was different between young and old men. The 13C-EPA plasma half-life was ∼2 d for both young and old men (P = 0.485). The percentage dose recovered of 13C-EPA per hour as 13CO2 and the cumulative ß-oxidation of 13C-EPA did not differ between young and old men. At 7 d, however, old men had a >2.2-fold higher plasma 13C-DHA concentration synthesized from 13C-EPA compared with young men (Page = 0.03). 13C-AA metabolism was not different between young and old men. The 13C-AA plasma half-life was ∼4.4 d in both young and old participants (P = 0.589).Conclusions: The metabolism of 13C-AA was not modified by age, whereas 13C-EPA metabolism was slightly but significantly different in old compared with young men. The higher plasma 13C-DHA seen in old men may be a result of slower plasma DHA clearance with age. This trial was registered at clinicaltrials.gov as NCT02957188.

Characterization of the comparative drug binding to intra- (liver fatty acid binding protein) and extra- (human serum albumin) cellular proteins.

1. This study compared the extent, affinity, and kinetics of drug binding to human serum albumin (HSA) and liver fatty acid binding protein (LFABP) using ultrafiltration and surface plasmon resonance (SPR). 2. Binding of basic and neutral drugs to both HSA and LFABP was typically negligible. Binding of acidic drugs ranged from minor (fu > 0.8) to extensive (fu < 0.1). Of the compounds screened, the highest binding to both HSA and LFABP was observed for the acidic drugs torsemide and sulfinpyrazone, and for ß-estradiol (a polar, neutral compound). 3. The extent of binding of acidic drugs to HSA was up to 40% greater than binding to LFABP. SPR experiments demonstrated comparable kinetics and affinity for the binding of representative acidic drugs (naproxen, sulfinpyrazone, and torsemide) to HSA and LFABP. 4. Simulations based on in vitro kinetic constants derived from SPR experiments and a rapid equilibrium model were undertaken to examine the impact of binding characteristics on compartmental drug distribution. Simulations provided mechanistic confirmation that equilibration of intracellular unbound drug with the extracellular unbound drug is attained rapidly in the absence of active transport mechanisms for drugs bound moderately or extensively to HSA and LFABP.

Artificial gait in complete spinal cord injured subjects: how to assess clinical performance / Marcha artificial em indivíduos com lesão medular completa: como avaliar desempenho clínico

Objective Adapt the 6 minutes walking test (6MWT) to artificial gait in complete spinal cord injured (SCI) patients aided by neuromuscular electrical stimulation. Method Nine male individuals with paraplegia (AIS A) participated in this study. Lesion levels varied between T4 and T12 and time post injured from 4 to 13 years. Patients performed 6MWT 1 and 6MWT 2. They used neuromuscular electrical stimulation, and were aided by a walker. The differences between two 6MWT were assessed by using a paired t test. Multiple r-squared was also calculated. Results The 6MWT 1 and 6MWT 2 were not statistically different for heart rate, distance, mean speed and blood pressure. Multiple r-squared (r2 = 0.96) explained 96% of the variation in the distance walked. Conclusion The use of 6MWT in artificial gait towards assessing exercise walking capacity is reproducible and easy to apply. It can be used to assess SCI artificial gait clinical performance. .

Objetivo Adaptar o teste de caminhada dos 6 minutos (TC6) para marcha artificial de pacientes com lesão medular completa associado a eletroestimulação neuromuscular. Método Nove participantes do sexo masculino com paraplegia (AIS A) participaram do estudo. O nível de lesão variou entre T4 e T12 , tempo de lesão variou entre 4 e 13 anos. Os pacientes realizaram dois TC6 (TC6-1 e TC6-2). Os participantes usaram eletroestimulação neuromuscular e foram auxiliados por andador. As diferenças entre os dois TC6 foram avaliadas pelo teste t pareado e calculado o r2. Resultados Não foi encontrada diferença estatística entre TC6-1 e TC6-2 para frequência cardíaca, distância, velocidade média e pressão arterial. O r2 = 0,96 explica 96% da variação na distância caminhada. Conclusão O uso do TC6 em marcha artificial para avaliação da capacidade de exercício de caminhada é reprodutível e fácil de aplicar. Esse teste pode ser utilizado para avaliar o desempenho clínico da marcha artificial de indivíduos com lesão medular. .

rhBSSL improves growth and LCPUFA absorption in preterm infants fed formula or pasteurized breast milk.

OBJECTIVES: Preterm infants often experience suboptimal growth, which can affect organ development. The aim of this study was to improve growth by treatment with bile salt-stimulated lipase (BSSL), naturally present in breast milk, but lost after pasteurization, and absent in formula. METHODS: Two clinical trials were performed with a predefined analysis of combined data to investigate the effects of recombinant human BSSL (rhBSSL) treatment on growth velocity and fat absorption in preterm infants. The studies were randomized and double-blinded comparing 7-day treatment with rhBSSL and placebo, administered in pasteurized breast milk or formula, using a crossover design. RESULTS: Sixty-three infants were evaluated for safety. At randomization, the mean (standard deviation) weight was 1467 (193) g and mean postmenstrual age was 32.6 (0.5) weeks. Sixty and 46 infants were evaluated for growth velocity and fat absorption, respectively. rhBSSL treatment significantly improved mean growth velocity by 2.93 g · kg · day (P<0.001) compared with placebo (mean 16.86 vs 13.93 g · kg · day) and significantly decreased the risk of suboptimal growth (<15 g · kg · day) (30% vs 52%, P=0.004). rhBSSL significantly increased absorption of the long-chain polyunsaturated fatty acids, docosahexaenoic acid, and arachidonic acid by 5.76% (P=0.013) and 8.55% (P=0.001), respectively, but had no significant effect on total fat absorption. The adverse-event profile was similar to placebo. CONCLUSIONS: In preterm infants fed pasteurized breast milk or formula, 1 week of treatment with rhBSSL was well tolerated and significantly improved growth and long-chain polyunsaturated fatty acid absorption compared to placebo. This publication presents the first data regarding the use of rhBSSL in preterms and the results have led to further clinical studies.

Dietary supplementation of arachidonic acid increases arachidonic acid and lipoxin A4 contents in colon, but does not affect severity or prostaglandin E2 content in murine colitis model.

BACKGROUND: Arachidonic acid (ARA) is an essential fatty acid and a major constituent of biomembranes. It is converted into various lipid mediators, such as prostaglandin E2 (PGE2) and lipoxin A4 (LXA4). The effects of dietary ARA on colon maintenance are unclear because PGE2 has both mucosal protective and proinflammatory effects, and LXA4 has an anti-inflammatory role. Our objective is to clarify the effects of dietary ARA on an experimental murine colitis model. METHODS: C57BL/6 mice were fed three types of ARA diet (0.075%, 0.15% or 0.305% ARA in diet), DHA diet (0.315% DHA) or control diet for 6 weeks, and were then administered dextran sodium sulphate (DSS) for 7 days to induce colitis. We evaluated colitis severity, fatty acid and lipid mediator contents in colonic tissue, and the expression of genes related to lipid mediator formation. RESULTS: ARA composition of colon phospholipids was significantly elevated in an ARA dose-dependent manner. ARA, as well as DHA, did not affect colitis severity (body weight loss, colon shortening, diarrhea and hemoccult phenomena) and histological features. PGE2 contents in the colon were unchanged by dietary ARA, while LXA4 contents increased in an ARA dose-dependent manner. Gene expression of cyclooxygenase (COX)-1 and COX-2 was unchanged, while that of 12/15-lipoxgenase (LOX) was significantly increased by dietary ARA. ARA composition did not correlate with neither colon length nor PGE2 contents, but significantly correlated with LXA4 content. CONCLUSION: These results suggest that dietary ARA increases ARA and LXA4 contents in colon, but that it has no effect on severity and PGE2 content in a DSS-induced murine colitis model.

The synthesis and in vivo pharmacokinetics of fluorinated arachidonic acid: implications for imaging neuroinflammation.

UNLABELLED: Arachidonic acid (AA) is found in high concentrations in brain phospholipids and is released as a second messenger during neurotransmission and much more so during neuroinflammation and excitotoxicity. Upregulated brain AA metabolism associated with neuroinflammation has been imaged in rodents using [1-(14)C]AA and with PET in Alzheimer disease patients using [1-(11)C]AA. Radiotracer brain AA uptake is independent of cerebral blood flow, making it an ideal tracer despite altered brain functional activity. However, the 20.4-min radioactive half-life of (11)C-AA and challenges of routinely synthesizing (11)C fatty acids limit their translational utility as PET biomarkers. METHODS: As a first step to develop a clinically useful (18)F-fluoroarachidonic acid ((18)F-FAA) with a long radioactive half-life of 109.8 min, we report here a high-yield stereoselective synthetic method of nonradioactive 20-(19)F-FAA. We tested its in vivo pharmacokinetics by infusing purified nonradioactive (19)F-FAA intravenously for 5 min at 2 doses in unanesthetized mice and measured its plasma and brain distribution using gas chromatography-mass spectrometry. RESULTS: Incorporation coefficients of injected (19)F-FAA into brain phospholipids (ratio of brain (19)F-FAA concentration to plasma input function) were 3- to 29-fold higher for choline glycerophospholipid and phosphatidylinositol than for ethanolamine glycerophospholipid and phosphatidylserine at each of the 2 tested doses. The selectivities and values of incorporation coefficients were comparable to those reported after [1-(14)C]AA (the natural arachidonate) infusion in mice. CONCLUSION: These results suggest that it would be worthwhile to translate our stereoselective synthetic method for (19)F-FAA to synthesize positron-emitting (18)F-FAA for human brain AA metabolism in neuroinflammatory disorders such as Alzheimer disease.

Supplementation of arachidonic acid-enriched oil increases arachidonic acid contents in plasma phospholipids, but does not increase their metabolites and clinical parameters in Japanese healthy elderly individuals: a randomized controlled study.

BACKGROUND: The importance of arachidonic acid (ARA) among the elderly has recently gained increased attention. The effects of ARA supplementation in the elderly are not fully understood, although ARA is considered to be associated with various diseases. We investigate whether ARA supplementation to Japanese elderly subjects affects clinical parameters involved in cardiovascular, inflammatory, and allergic diseases. We also examine the levels of ARA metabolites such as prostanoids during intervention. METHODS: We conducted a randomized, double-blind and placebo-controlled parallel group intervention trial. ARA-enriched oil (240 or 720 mg ARA per day) or placebo was administered to Japanese healthy men and women aged 55-70 years for 4 weeks followed by a 4-week washout period. The fatty acid contents of plasma phospholipids, clinical parameters, and ARA metabolites were determined at baseline, 2, 4, and 8 weeks. RESULTS: The ARA content in plasma phospholipids in the ARA-administrated groups increased dose-dependently and was almost the same at 2 weeks and at 4 weeks. The elevated ARA content decreased to nearly baseline during a 4-week washout period. During the supplementation and washout periods, no changes were observed in eicosapentaenoic acid and docosahexaenoic acid contents. There were no changes in clinical blood parameters related to cardiovascular, inflammatory and allergic diseases. ARA supplementation did not alter the level of ARA metabolites such as urinary 11-dehydro thromboxane B2, 2,3-dinor-6-keto prostaglandin (PG) F1α and 9,15-dioxo-11α-hydroxy-13,14-dihydro-2,3,4,5-tetranor-prostan-1,20-dioic acid (tetranor-PGEM), and plasma PGE2 and lipoxin A4. ARA in plasma phospholipids was not correlated with ARA metabolite levels in the blood or urine. CONCLUSION: These results indicate that ARA supplementation, even at a relatively high dose, does not increase ARA metabolites, and suggest that it does not induce cardiovascular, inflammatory or allergic diseases in Japanese elderly individuals.

Chronic valproate treatment blocks D2-like receptor-mediated brain signaling via arachidonic acid in rats.

BACKGROUND AND OBJECTIVE: Hyperdopaminergic signaling and an upregulated brain arachidonic acid (AA) cascade may contribute to bipolar disorder (BD). Lithium and carbamazepine, FDA-approved for the treatment of BD, attenuate brain dopaminergic D(2)-like (D(2), D(3), and D(4)) receptor signaling involving AA when given chronically to awake rats. We hypothesized that valproate (VPA), with mood-stabilizing properties, would also reduce D(2)-like-mediated signaling via AA. METHODS: An acute dose of quinpirole (1 mg/kg) or saline was administered to unanesthetized rats that had been treated for 30 days with a therapeutically relevant dose of VPA (200 mg/kg/day) or vehicle. Regional brain AA incorporation coefficients, k*, and incorporation rates, J(in), markers of AA signaling and metabolism, were measured by quantitative autoradiography after intravenous [1-(14)C]AA infusion. Whole brain concentrations of prostaglandin (PG)E(2) and thromboxane (TX)B(2) also were measured. RESULTS: Quinpirole compared to saline significantly increased k* in 40 of 83 brain regions, and increased brain concentrations of PGE(2) in chronic vehicle-treated rats. VPA treatment by itself reduced concentrations of plasma unesterified AA and whole brain PGE(2) and TXB(2), and blocked the quinpirole-induced increments in k* and PGE(2). CONCLUSION: These results further provide evidence that mood stabilizers downregulate brain dopaminergic D(2)-like receptor signaling involving AA.

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.

Placental transfer of fatty acids and fetal implications.

Considerable amounts of long-chain polyunsaturated fatty acids (LC-PUFAs), particularly arachidonic acid and docosahexaenoic acid (DHA, 22:6n-3), are deposited in fetal tissues during pregnancy; and this process is facilitated by placental delivery. Nevertheless, the mechanisms involved in LC-PUFA placental transfer remain unclear. Stable isotope techniques have been used to study human placental fatty acid transfer in vivo. These studies have shown a significantly higher ratio of (13)C-DHA in cord to maternal plasma compared with other fatty acids, which reflects a higher placental DHA transfer. In addition, a selective DHA accumulation in placental tissue, relative to other fatty acids, has been reported. The materno-fetal transfer of fatty acids is a slow process that requires ≥12 h. A high incorporation of dietary (13)C-DHA into maternal plasma phospholipids appears to be important for placental uptake and transfer. DHA in cord blood lipids correlates with placental messenger RNA expression of fatty acid transport protein (FATP)-4, compatible with a role of FATP-4 in DHA transfer. Impaired materno-fetal LC-PUFA transport has been proposed in pregnancies complicated by abnormal placental function (eg, due to gestational diabetes mellitus or intrauterine growth restriction), which should be addressed in future studies. Given that placental DHA transfer is important for child outcomes, elucidation of its potential modulation by transport mechanisms, maternal diet, and disease appears to be important.

Simultaneous quantification of total eicosapentaenoic acid, docosahexaenoic acid and arachidonic acid in plasma by high-performance liquid chromatography-tandem mass spectrometry.

A method for the simultaneous quantification of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and arachidonic acid (AA) in human plasma by HPLC-tandem mass spectrometry (HPLC-MS/MS) was developed and validated. Free and esterified forms of fatty acids were hydrolysed from plasma samples in the presence of an internal standard and subjected to liquid-liquid extraction. The chromatographic run time was 3.5 min per sample. The assay was linear from 0.5 to 300 mg/L (r(2) > 0.997, n = 18). Based on matrix addition, accuracy deviation was <15%, except for AA at 10 mg/L (30-90%), whereas precision was <8% for all fatty acids studied. The method was applied to the measurement of these omega-3 fatty acids in a fish oil supplement study with healthy volunteers. Healthy males (n = 4) were administered a supplement containing 465 mg EPA and 375 mg DHA per capsule (Omacor®). A dose of two capsules was given daily over a 4 week period. Pre-treatment concentrations varied between subjects for EPA (17-68 mg/L), DHA (36-63 mg/L) and AA (121-248 mg/L). During the dosing period EPA increased 460-480% from the baseline concentration, while DHA increased 150-160%. The EPA-AA ratio increased from 0.07-0.56 to 0.3-3.1 after 4 weeks of dosing. In conclusion, the method described could be suitable for monitoring EPA, DHA and AA in clinical studies that may aid in achieving optimal concentrations of these fatty acids in patients who could be at risk of sudden cardiac death.

El óxido nítrico como mediador de la respuesta inflamatoria. Su importancia en el movimiento dental / Nitric oxide as mediator of the inflammatory response. His importance in the dental movement

El movimiento dental ortodóncico induce per se cambios inflamatorios en los tejidos dentales. En este artículo analizamos el papel dual que puede desempeñar el óxido nítrico, pudiendo comportarse como cito protector y antiinflamatorio o bien como citotóxico y mediador del daño celular. Valoramos su función como mediador de la respuesta inflamatoria y su posible efecto protector, así como su papel de modulador de la respuesta inflamatoria tanto a nivel sistémico como local (AU)

The orthodontic tooth movement induces per se inflammatory changes in the dental tissues. In this article we analyze the dual role that can have the nitric oxide, being able to behave as citoprotective and anti.inflammatory or as citotoxic and mediator of the cellular damage. We value his function as mediator of the inflammatory response and his possible protective effect, as well as his role of modulator of the inflammatory response both at systemic and local level (AU)

Low-dose arachidonic acid intake increases erythrocytes and plasma arachidonic acid in young women.

Arachidonic acid (ARA) is considered to be a minor contributor to the diet. Previous reports regarding the effect of ARA supplementation on the composition of long-chain polyunsaturated fatty acids (LCPUFA) in the blood of humans are extremely limited. In the present study, we conducted a crossover double-blind, placebo-control study. Twenty-three young Japanese women consumed one capsule containing triacylglycerol enriched with 80 mg ARA, equivalent to the amount in one egg, daily for 3 weeks. Blood samples were drawn before and after treatment periods, and the compositions of the LCPUFA in blood lipid fractions were measured. The supplementation of ARA increased the composition of ARA, but did not decrease the composition of n-3LCPUFA in erythrocyte phospholipids and plasma phospholipids, esterified cholesterol, and triacylglycerol. We found that dietary ARA increased the ARA level in all lipid fractions of the blood, even at a very low dose.

Maternal di-(2-ethylhexyl)-phthalate exposure influences essential fatty acid homeostasis in rat placenta.

Maintaining essential fatty acid (EFA) homeostasis during pregnancy is critical for fetal development. As the organ that controls the maternal-to-fetal supply of nutrients, the placenta plays a significant role in guiding EFA transfer to the fetus. Many EFA homeostasis proteins are regulated by peroxisome proliferator-activated receptors (PPARs). The metabolites of di-(2-ethylhexyl)-phthalate (DEHP), a ubiquitous environmental contaminant, might influence EFA homeostasis via trans-activation of PPARs with subsequent downstream effects on EFA transporters and enzymes. To investigate DEHP's effect on placental/fetal EFA homeostasis, female Sprague-Dawley rats were orally gavaged with either vehicle or DEHP at 750 or 1500 mg/kg/day from gestational day (GD) 0 to GD 19. Changes in the expression of several EFA homeostasis regulating proteins were determined in the junctional (JXN) and labyrinthine (LAB) zones of the placenta, including PPAR isoforms (alpha, beta and gamma), fatty acid translocase (FAT/CD36), fatty acid transport protein 1 (FATP1), plasma membrane fatty acid binding protein (FABPpm), heart cytoplasmic fatty acid binding protein (HFABP), cytochrome P450 (CYP) 4A1, and cyclooxygenase (COX)-1 and -2. Additionally, effects of DEHP maternal exposure on the placental transfer and fetal distribution of representative EFAs, arachidonic acid (AA) and docosahexaenoic acid (DHA), and the placental production of prostaglandins (PGs) were investigated. Expression of PPARalpha, PPARgamma, FAT/CD36, FATP1, HFABP and CYP4A1 was up-regulated in JXN and/or LAB while COX-2 was down-regulated in JXN. PPARbeta, FABPpm, and COX-1 demonstrated variable expression. Reduced directional maternal-to-fetal placental transfer and altered fetal distribution of AA and DHA were observed in concordance with a decreased total placental PG production. These results correlate with previous in vitro data, suggesting that DEHP could influence placental EFA homeostasis with potential downstream effects in the developing fetus.

Chronic d-amphetamine depresses an imaging marker of arachidonic acid metabolism in rat brain.

Acute d-amphetamine (d-Amph) administration to rats leads to the release of arachidonic acid (AA, 20:4n-6) as a second messenger following indirect agonism at dopamine D2-like receptors in the brain. We hypothesized that chronically administered d-Amph in rats also would alter brain AA metabolism and signalling. To test this, adult male rats were injected i.p. daily for 2 wk with saline or 2.5 mg/kg d-Amph. After a 1-d washout, the unanaesthetized rats were injected acutely with i.v. saline, 1 mg/kg quinpirole (a D2-like receptor agonist) or 5.0 mg/kg SKF-38393 (a D1-like receptor agonist), followed by i.v. [1-14C]AA. The AA incorporation coefficient k* (brain radioactivity/integrated plasma radioactivity), a marker of AA signalling and metabolism, was quantified using autoradiography in each of 62 brain regions. Compared with chronic saline, chronic d-Amph widely decreased baseline values of k* in brain regions having D2-like receptors. On the other hand, chronic amphetamine did not alter the k* responses to quinpirole seen in chronic saline-treated rats. SKF-38393 had minimal effects on k* in both chronic saline-treated and amphetamine-treated rats, consistent with D1-like receptors not being coupled to AA signalling. The ability of chronic d-Amph after 1-d washout to down-regulate baseline values of k* probably reflects neuroplastic changes in brain AA signalling, and may correspond to depressive behaviours noted following withdrawal from chronic amphetamine in humans and in rats.

Arachidonic acid and glucose uptake by freshly isolated human adipocytes.

Fatty acid (FA) and glucose transport into insulin-dependent cells are impaired in insulin resistance (IR; type 2 diabetes mellitus). Studies done on the effects of FAs on glucose uptake, and the influence of insulin on FA uptake by adipocytes, have yielded contradictory results. In this study, isolated human adipocytes were exposed to arachidonic acid (AA) and to insulin, and FA uptake as well as glucose uptake was measured. AA uptake into adipocyte membranes and nuclei was also investigated. Glucose uptake was inhibited by 57 +/- 8% after 30 min of exposure to arachidonate. AA was significantly taken up into adipocyte membranes (49.6 +/- 29% and 123 +/- 74%) at 20 and 30 min of exposure, respectively, and into nuclei (147.6 +/- 19.2%) after 30 min. Insulin stimulated AA uptake (24.1 +/- 14.1%) at 30 min by adipocytes from a non-obese subject, while inhibiting it (16.6 +/- 12%) in adipocytes from an obese subject. These results suggest that: (1) AA inhibits glucose uptake by adipocytes exposed over a short period, probably by a membrane-associated mechanism, (2) insulin-dependent AA uptake is dependent on the body mass index (BMI) of the donor and the insulin sensitivity of their adipocytes.

Differential tissue dose responses of (n-3) and (n-6) PUFA in neonatal piglets fed docosahexaenoate and arachidonoate.

Docosahexaenoic acid (DHA) and arachidonic acid (ARA) are commonly added to infant formula worldwide; however, dietary concentrations needed to obtain optimal tissue levels have not been established. Hence, we studied tissue responses in piglets fed various doses of DHA and ARA. Doses were 0, 1, 2, and 5 times those used in U.S. infant formulas and DHA/ARA in Diet 0, Diet 1, Diet 2, and Diet 5 were 0, 4.1/8.1, 8.1/16.2, and 20.3/40.6 mg/100 kJ formula, respectively. Supplementation of dietary DHA and ARA increased DHA in brain, retina, liver, adipose tissue, plasma, and erythrocyte by 1.1- to 25.8-fold of Diet 0 (P-trend < 0.01). Tissue ARA (1.1- to 6.0-fold of Diet 0) responded to dietary ARA in liver, adipose tissue, plasma, and erythrocytes (P-trend < 0.05); brain and retina ARA was, however, unresponsive to dietary DHA and ARA. Plasma and erythrocyte DHA were positively associated with DHA in neural (brain and retina) and visceral (liver and adipose) tissues (r(2) = 0.11-0.56; P < 0.001-P = 0.042). Plasma and erythrocyte ARA did not correlate with neural ARA. Only plasma ARA was associated with liver ARA (r(2) = 0.222; P = 0.02) and adipose ARA (r(2) = 0.867; P < 0.001) and erythrocyte ARA correlated with adipose ARA (r(2) = 0.470; P < 0.001). We conclude that dietary DHA supplementation affords an effective strategy for enhancing tissue DHA, ARA in visceral but not neural tissues is sensitive to dietary ARA, and erythrocyte and plasma DHA can be used as proxies for tissue DHA, although blood-borne ARA is not an indicator of neural ARA.

Assessment of skin absorption and irritation potential of arachidonic acid and glyceryl arachidonate using in vitro diffusion cell techniques.

Arachidonic acid (AA), a precursor of pro-inflammatory mediators, and its glycerin ester, glyceryl arachidonate (GA), are reportedly used in cosmetic products. In vitro skin penetration of AA and GA and GA's ester hydrolysis was determined in flow-through diffusion cells. AA penetration with human and rat skin was 19.5% and 52.3% of the applied dose respectively, a substantial amount of which remained in the skin at 24h. Similar penetration results were obtained with GA in human skin. However, GA penetration through cultured skin (EpiDerm) was 51% of the applied dose, almost all of which appeared in the receptor fluid. At least 27.8% of GA penetrating skin was hydrolyzed to AA. In vitro methods were used to assess skin irritation in diffusion cells. Skin irritation of AA, sodium lauryl sulfate (SLS), and Tween 80 was determined by changes in transepidermal water loss (TEWL), skin viability (3-(4,5-dimethylthiaxol-2-yl)-2,5-diphenyltetrazolium bromide, MTT, formation), and cytokine release (IL-1alpha). SLS irritation was much less pronounced in an emulsion versus an aqueous vehicle. No significant irritation was observed in vitro from AA in an emulsion. This work predicts that AA would penetrate human skin in vivo and that it could be formed in skin from topically applied GA.

Enhanced vasoconstrictor prostanoid production by sinusoidal endothelial cells increases portal perfusion pressure in cirrhotic rat livers.

BACKGROUND/AIMS: Cyclooxygenase-1 (COX-1) is overexpressed in sinusoidal endothelial cells (SEC) of cirrhotic rat livers, and through an enhanced production of vasoconstrictor prostanoids contributes to increase intrahepatic resistance. Our study was aimed at investigating the role of enhanced AA bioavailability modulating the hepatic vascular tone of cirrhotic livers and identifying which prostanoid is involved. METHODS: SEC isolated from control and cirrhotic rat livers were incubated with AA, methoxamine or vehicle. TXA(2) was quantified. In addition, portal perfusion pressure (PP) response curves to AA were performed in rat livers pre-incubated with vehicle, SC-560 (COX-1 inhibitor), Furegrelate (inhibitor of TXA(2) synthesis) and SQ-29548 (PGH(2)/TXA(2) receptor blocker). cPLA2 activity was determined in control and cirrhotic livers. RESULTS: AA and methoxamine incubation promoted a significant increase in TXA(2) release by Cirrhotic-SEC, but not in Control-SEC. AA produced a dose-dependent increase in the PP, associated with increased TXA(2) release. These responses were significantly greater in cirrhotic livers. COX-1 inhibition and PGH(2)/TXA(2) receptor blockade, but not TXA(2) synthase inhibition, markedly attenuated the PP response to AA of cirrhotic livers. Additionally, cirrhotic livers exhibited significantly increased cPLA2 activity. CONCLUSIONS: An enhanced production of vasoconstrictor prostanoids, probably PGH(2), by SEC contributes to increase vascular tone of cirrhotic livers.