Oil for Life to Balance omega-3 polyunsaturated fatty acids ... - Oil4Life

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4. FUNCTION OF PUFA IN CELL MEMBRANE PHOSPHOLIPIDS Besides the structural role already described the long chain fatty acids incorporated in membrane phospholipids has another important function, completely different. After the release mediated by a specific phospholipase A2, AA and EPA are oxidized by specific enzyme giving origin to cellular mediators, namely prostaglandins, leukotrienes, thromboxane, prostacyclins. However, several other classes can technically be termed eicosanoids, including the hepoxilins, resolvins, isofurans, isoprostanes, lipoxins, epi-lipoxins, epoxyeicosatrienoic acids (EETs) and endocannabinoids. LTs and prostanoids are sometimes termed 'classic eicosanoids' (Van Dyke T.E. et al., 2003, Serhan C.N. et al., 2004, Anderle P. et al., 2004) in contrast to the 'novel', 'eicosanoid-like' or 'nonclassic eicosanoids' (Evans A.R. et al., 2000, O'Brien W.F. et al., 1993, Behrendt H. et al., 2001, Sarau H.M. et al., 1999) As already reported above, eicosanoids are signaling molecules made by oxygenation of twenty-carbon fatty acids. They exert complex control over many systems, mainly in inflammation or immunity, and as messengers in the central nervous system. The networks of controls that depend upon eicosanoids are among the most complex in the human body. Eicosanoids derive from either omega-3 or omega-6. The n-6 eicosanoids are generally proinflammatory; n-3's are much less so. The amounts and balance of fats in a diet will affect the body's eicosanoid-controlled functions, with effects on cardiovascular disease, triglycerides concentration, blood pressure, arthritis, inflammation and oxidative/nitrosative conditions. 4.1 Biosynthesis Two families of enzymes catalyze fatty acid oxygenation to produce the eicosanoids:Cyclooxygenase, or COX, generates the prostanoids. Lipoxygenase, in several forms, e.g. 5-lipoxygenase (5-LO) generates the leukotrienes. Eicosanoids are not stored within cells, but are synthesized as required. Eicosanoid biosynthesis begins when cell is activated by mechanical trauma, cytokines, growth factors or other stimuli. (The stimulus may even be an eicosanoid from a neighboring cell; the pathways are complex). Phospholipase is released at the cell membrane and travels to the nuclear membrane. There, it frees 20-carbon fatty acids. This event appears to be the rate-determining step for eicosanoid formation. A schematic view of conversion of AA and EPA to prostanoids and leukotrienes through the cyclo oxigenase and lipo oxigenase pathway are depicted in the following figure: 19
Figure 5: The three groups of eicosanoids and their biosynthetic origins. (PG, prostaglandin; PGI, prostacyclin; TX, thromboxane; LT, leukotriene; LX, lipoxin; 1, cyclooxigenase; 2, lipoxygenase pathway). The subscript denotes the total number of double bonds in the molecules and the series to which the compound belongs. Adapted by: Murray R.K. Granner D.K., Mayes P.A., Rodwell V.W. (2003). Harper’s Illustrated Biochemistry. 23: 193. Thromboxane are synthesized in platelets and upon release cause vasoconstriction and platelet aggregation. Their synthesis is specifically inhibited by low-dose aspirin. Prostacyclins (PGI2) are produced by blood vessel walls and are potent inhibitors of platelet aggregation. Thus, thromboxanes and prostacyclins are antagonistic. PG3 and TX3 formed from eicosapentaenoic acid inhibits the release of arachidonate from phospholipids and deformation of PG2 and TX2. PGI3 is a potent antiaggregator of platelet as PGI2, but TXA3 is a wicker aggregator than TXA2, changing the balance and favouring longer clotting times. Potential therapeutic uses of prostaglandins include prevention of conception induction of labor at term, termination of pregnancy, prevention or alleviation of gastric ulcers, control of inflammation and of blood pressure, and relief of asthma and nasal congestion. Slow-reactive substance of anaphylaxis (SRS-A) is a mixture of leukotrienes C4, D4 and E4. 20
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Page 3 and 4: omega-3 has been associated with in
Page 5 and 6: 10 kg/day of EPA+DHA 2:1 as in Oil4
Page 7 and 8: SUMMARY 1. Olive oil - a strong ant
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Page 11 and 12: acid incorporated into cell membran
Page 13 and 14: Supplementation with omega-3 were l
Page 15 and 16: 18:3 ω-3 ALA 18:2 ω-6 LA Δ6-desa
Page 17 and 18: Figure 3: The cell membrane. The ce
Page 19: In animal cells cholesterol is norm
Page 23 and 24: and men, respectively (London S.J.
Page 25 and 26: 6.3. Hypertension Different mechani
Page 27 and 28: function in the dopaminergic synaps
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Page 31 and 32: 8. CLINICAL STUDIES AT THE UNIVERSI
Page 33 and 34: effects were found also in our expe
Page 35 and 36: In the 1994 Diagnostic and Statisti
Page 37 and 38: REFERENCES � Adams P.B., Sinclair
Page 39 and 40: � Byers T., Gieseker K.(1997) Iss
Page 41 and 42: consumption and questionnaire data
Page 43 and 44: � Leitzmann M.F., Stampfer M.J.,
Page 45 and 46: anxiety. Journal of the American Ac
Page 47 and 48: � Thapar A., O’Donovan M., Owen
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