Specifically, dietary supplementation with omega-3 PUFAs is thought to increase the abundance of omega-3 PUFAs in membrane phospholipids which can then inhibit AA-dependent signalling either directly, by replacing AA as the eicosanoid substrate of cyclooxygenases and lipoxygenases, or indirectly by altering the expression of proteins involved in the signalling cascade. Although EPA is a minor brain fatty acid compared to the abundant DHA, both omega-3 PUFAs are equally effective inhibitors of AA-derived eicosanoid synthesis, a finding which is at odds with the observation that EPAmay be more clinically efficacious in the treatment of mood disorders. An in vitro observation indicates that long term supplementation with EPA can increase the stimulated release of AA from membrane phospholipids, whereas DHA has no effect. This role of EPA was likely due to it inhibiting the re-uptake of AA to reform an intact phospholipid, a two enzyme metabolic pathway which acts to reverse the hydrolysis of the AA-containing phospholipid by phospholipase A2. EPA can inhibit the expression and/or activity of the enzymes lysophospholipid acyltransferase (LPAT) or fatty acid CoA ligase (FACL), both of which are required for reuptake of AA to occur. Indeed, reduced activity of FACL appears to enhance AA-dependent signaling reactions since reduced reuptake will increase the supply of AA available for eicosanoid synthesis.
Specifically, dietary supplementation with omega-3 PUFAs is thought to increase the abundance of omega-3 PUFAs in membrane phospholipids which can then inhibit AA-dependent signalling either directly, by replacing AA as the eicosanoid substrate of cyclooxygenases and lipoxygenases, or indirectly by altering the expression of proteins involved in the signalling cascade. Although EPA is a minor brain fatty acid compared to the abundant DHA, both omega-3 PUFAs are equally effective inhibitors of AA-derived eicosanoid synthesis, a finding which is at odds with the observation that EPAmay be more clinically efficacious in the treatment of mood disorders. An in vitro observation indicates that long term supplementation with EPA can increase the stimulated release of AA from membrane phospholipids, whereas DHA has no effect. This role of EPA was likely due to it inhibiting the re-uptake of AA to reform an intact phospholipid, a two enzyme metabolic pathway which acts to reverse the hydrolysis of the AA-containing phospholipid by phospholipase A2. EPA can inhibit the expression and/or activity of the enzymes lysophospholipid acyltransferase (LPAT) or fatty acid CoA ligase (FACL), both of which are required for reuptake of AA to occur. Indeed, reduced activity of FACL appears to enhance AA-dependent signaling reactions since reduced reuptake will increase the supply of AA available for eicosanoid synthesis.
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