Alpha-linolenic Acid Treatment Research Articles

Chronic alpha-linolenic acid treatment alleviates age-associated neuropathology: Roles of PERK/eIF2α signaling pathway

Aging is a principal risk factor for neurodegenerative diseases and especially shares similar pathologic mechanisms to Alzheimer’s disease (AD). Amyloid-β (Aβ) plaques deposition and neurofibrillary tangles (NFTs) are the prominent age-dependent pathologies implicated in the cognitive deficits. Accumulation of mis-folded proteins in the endoplasmic reticulum triggers a cellular stress response called the unfolded protein response (UPR), the activation of which is increased in AD patients. However, the UPR relates to the pathological hallmarks of aging is still elusive. In this study, we report that long-term supplement of α-linolenic acid (ALA), starting before the onset of disease symptoms (6month-old), prevents the age-related memory deficits during natural aging. The amelioration of the memory impairment is associated with a decrease in UPR related markers [glucose regulated protein 78 (GRP78), protein kinase RNA-like endoplasmic reticulum kinase (PERK), eukaryotic Initiation Factor 2α (eIF2α)]. ALA suppressed the PERK/eIF2α signaling, which may be responsible for multifaceted memory-deteriorating and neurodegenerative mechanisms, including inhibition of Aβ production by suppressing β-site APP-cleaving enzyme 1 (BACE1) expression, enhancement of cAMP response element binding protein (CREB) function via down-regulating activating transcription factor 4 (ATF4), and suppression of Tau phosphorylation by inhibiting glycogen synthase kinase 3β (GSK-3β) pathway. Taken together, our findings provide new insights into the link between ALA and PERK/eIF2α signaling, which could contribute to a better understanding of an ALA-mediated protective effect in aging-associated neuropathology.

Dietary omega-3 alpha-linolenic acid does not prevent venous thrombosis in mice

Venous thromboembolism (VTE) is a leading cause of cardiovascular death. Omega-3 fatty acids (n-3 FA) exhibit protective effects against cardiovascular disease. Others and our group have reported that the plant-derived n-3 FA alpha-linolenic acid (ALA) displays antiinflammatory, anticoagulant and antiplatelet effects, thereby reducing atherosclerosis and arterial thrombosis in mice fed a high ALA diet. Since procoagulant factors such as tissue factor and fibrin as well as platelets and leukocytes are crucially involved in the development of VTE, we investigated possible protective effects of dietary ALA on venous thrombus formation in a mouse model of stenosis- and furthermore, in a mouse model of endothelial injury-induced venous thrombosis. Four week old C57BL/6 mice underwent four weeks of high (7.3g%) or low ALA (0.03g%) treatment before being exposed to inferior vena cava (IVC) stenosis for 48 hours or laser injury of the endothelium of the internal jugular vein (IJV). Thrombus generation frequency, thrombus size and composition (IVC stenosis group) and time to thrombus formation (endothelial injury group) were assessed. In addition, plasma glycocalicin, a marker of platelet activation, platelet P-selectin and activated integrin expression as well as plasma thrombin generation was determined, but did not reveal any significant differences between the groups. Despite its protective properties against arterial thrombus formation, dietary ALA did not protect against venous thrombosis neither in the IVC stenosis nor the endothelial injury model, further indicating that the biological processes involved in arterial and venous thrombosis are different.

Down-regulation of malignant potential by alpha linolenic acid in human and mouse colon cancer cells.

Omega-3 fatty acids (also called ω-3 fatty acis or n-3 fatty acid) are polyunsaturated fatty acids (PUFAs) with a double bond (C=C) at the third carbon atom from the end of the carbon chain. Numerous test tube and animal studies have shown that omega-3 fatty acids may prevent or inhibit the growth of cancers, suggesting that omega-3 fatty acids are important in cancer physiology. Alpha-linolenic acid (ALA) is one of an essential omega-3 fatty acid and organic compound found in seeds (chia and flaxseed), nuts (notably walnuts), and many common vegetable oils. ALA has also been shown to down-regulate cell proliferation of prostate, breast, and bladder cancer cells. However, direct evidence that ALA suppresses to the development of colon cancer has not been studied. Also, no previous studies have evaluated whether ALA may regulate malignant potential (adhesion, invasion and colony formation) in colon cancer cells. In order to address the questions above, we conducted in vitro studies and evaluated whether ALA may down-regulate malignant potential in human (HT29 and HCT116) and mouse (MCA38) colon cancer cell lines. We observed that treatment with 1-5mM of ALA inhibits cell proliferation, adhesion and invasion in both human and mouse colon cancer cell lines. Interestingly, we observed that ALA did not decrease total colony numbers when compared to control. By contrast, we found that size of colony was significantly changed by ALA treatment when compared to control in all colon cancer cell lines. We suggest that our data enhance our current knowledge of ALA's mechanism and provide crucial information to further the development of new therapies for the management or chemoprevention of colon cancer.

No effect of n-3 fatty acids supplementation on NT-proBNP after myocardial infarction: the Alpha Omega Trial.

heart failure is a major risk factor for cardiovascular mortality, for which n-3 fatty acids may have beneficial effects. We examined the effect of marine eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), and plant-derived alpha-linolenic acid (ALA) on N-Terminal-pro Brain Natriuretic Peptide (NT-proBNP), a biomarker of heart failure. we randomly assigned 4837 post-myocardial infarction patients, aged 60-80 years (82% men), to margarines supplemented with a targeted additional intake of 400 mg/day EPA and DHA, 2 g/day ALA, EPA-DHA plus ALA, or placebo for 40 months. In a random selection of 639 patients, NT-proBNP was determined both at baseline and at the end of follow-up. NT-proBNP was loge-transformed and analysed by type of treatment using analysis of covariance adjusting for baseline NT-proNBP. patients consumed on average 19.8 g margarine/day, providing an additional amount of 238 mg/day EPA with 158 mg/day DHA, 1.98 g/day ALA, or both, in the active-treatment groups. In the placebo group, the geometric mean level NT-proBNP increased from 245 ng/l (95%-confidence interval [CI]: 207-290) to 294 ng/l (95%-CI: 244-352) after 40 months (p = 0.001). NT-proBNP levels were not affected by ALA (+8% versus placebo; 95%-CI: -8% to +25%; p = 0.34), EPA-DHA (+2% versus placebo; 95%-CI: -14% to +18%; p = 0.78), nor EPA-DHA plus ALA (+9% versus placebo; 95%-CI: -8% to +25%; p = 0.31) treatment. supplementation with modest amounts of EPA-DHA, with or without ALA, did not have a significant effect on NT-proBNP levels in patients with a history of myocardial infarction.

Dietary α-linolenic acid increases the platelet count in ApoE−/− mice by reducing clearance

AbstractPreviously we reported that dietary intake of alpha-linolenic acid (ALA) reduces atherogenesis and inhibits arterial thrombosis. Here, we analyze the substantial increase in platelet count induced by ALA and the mechanisms of reduced platelet clearance. Eight-week-old male apolipoprotein E knockout (ApoE−/−) mice were fed a 0.21g% cholesterol diet complemented by either a high- (7.3g%) or low-ALA (0.03g%) content. Platelet counts doubled after 16 weeks of ALA feeding, whereas the bleeding time remained similar. Plasma glycocalicin and glycocalicin index were reduced, while reticulated platelets, thrombopoietin, and bone marrow megakaryocyte colony-forming units remained unchanged. Platelet contents of liver and spleen were substantially reduced, without affecting macrophage function and number. Glycoprotein Ib (GPIb) shedding, exposure of P-selectin, and activated integrin αIIbβ3 upon activation with thrombin were reduced. Dietary ALA increased the platelet count by reducing platelet clearance in the reticulo-endothelial system. The latter appears to be mediated by reduced cleavage of GPIb by tumor necrosis factor-α–converting enzyme and reduced platelet activation/expression of procoagulant signaling. Ex vivo, there was less adhesion of human platelets to von Willebrand factor under high shear conditions after ALA treatment. Thus, ALA may be a promising tool in transfusion medicine and in high turnover/high activation platelet disorders.

Alpha-linolenic acid increases cholesterol efflux in macrophage-derived foam cells by decreasing stearoyl CoA desaturase 1 expression: evidence for a farnesoid-X-receptor mechanism of action

Increased cholesterol efflux from macrophage-derived foam cells (MDFCs) is an important protective mechanism to decrease lipid load in the atherosclerotic plaque. Dietary alpha-linolenic acid (ALA), an omega-3 polyunsaturated fatty acid (PUFA), decreases circulating cholesterol, but its role in cholesterol efflux has not been extensively studied. Stearoyl CoA desaturase 1 (SCD1) is the rate-limiting enzyme in the synthesis of monounsaturated fatty acids (MUFAs). Endogenous MUFAs are preferentially incorporated into triglycerides, phospholipids and cholesteryl ester, which are abundant in atherosclerotic plaque. This study investigated the mechanisms by which ALA regulated SCD1 and subsequent effect on cholesterol storage and transport in MDFCs. Small interfering RNA (siRNA) also was applied to modify SCD1 expression in foam cells. Alpha-linolenic acid treatment and SCD1 siRNA significantly decreased SCD1 expression in MDFCs. The reduction of SCD1 was accompanied with increased cholesterol efflux and decreased intracellular cholesterol storage within these cells. Alpha-linolenic acid activated the nuclear receptor farnesoid-X-receptor, which in turn increased its target gene small heterodimer partner (SHP) expression, and decreased liver-X-receptor dependent sterol regulatory element binding protein 1c transcription, ultimately resulting in repressed SCD1 expression. In conclusion, repression of SCD1 by ALA favorably increased cholesterol efflux and decreased cholesterol accumulation in foam cells. This may be one mechanism by which dietary omega-3 PUFAs promote atherosclerosis regression.

Subchronic Alpha-Linolenic Acid Treatment Enhances Brain Plasticity and Exerts an Antidepressant Effect: A Versatile Potential Therapy for Stroke

Omega-3 polyunsaturated fatty acids are known to have therapeutic potential in several neurological and psychiatric disorders. However, the molecular mechanisms of action underlying these effects are not well elucidated. We previously showed that alpha-linolenic acid (ALA) reduced ischemic brain damage after a single treatment. To follow-up this finding, we investigated whether subchronic ALA treatment promoted neuronal plasticity. Three sequential injections with a neuroprotective dose of ALA increased neurogenesis and expression of key proteins involved in synaptic functions, namely, synaptophysin-1, VAMP-2, and SNAP-25, as well as proteins supporting glutamatergic neurotransmission, namely, V-GLUT1 and V-GLUT2. These effects were correlated with an increase in brain-derived neurotrophic factor (BDNF) protein levels, both in vitro using neural stem cells and hippocampal cultures and in vivo, after subchronic ALA treatment. Given that BDNF has antidepressant activity, this led us to test whether subchronic ALA treatment could produce antidepressant-like behavior. ALA-treated mice had significantly reduced measures of depressive-like behavior compared with vehicle-treated animals, suggesting another aspect of ALA treatment that could stimulate functional stroke recovery by potentially combining acute neuroprotection with long-term repair/compensatory plasticity. Indeed, three sequential injections of ALA enhanced protection, either as a pretreatment, wherein it reduced post-ischemic infarct volume 24 h after a 1-hour occlusion of the middle cerebral artery or as post-treatment therapy, wherein it augmented animal survival rates by threefold 10 days after ischemia.

Alpha linolenic acid increases cholesterol efflux via regulation of stearoyl CoA desaturase in foam cells

Epidemiologic studies indicate that higher alpha linolenic acid (ALA) intake is associated with reduced cardiovascular disease risk. Stearoly CoA desaturase (SCD) is a rate‐limiting enzyme in lipogenesis by converting saturated fatty acids to monounsaturated fatty acids. Increased SCD activity is related with obesity, metabolic syndrome and atherosclerosis. There is some evidence that SCD1 also is involved in the cholesterol efflux from macrophage foam cells, important mediators of the atherogenic plaque. The current study was conducted to investigate the regulation of SCD1 by ALA and its contribution to cholesterol efflux. To induce foam cell formation, RAW 264.7 macrpohages were treated with oxidized low‐density lipoprotein (oxLDL). ALA treatment significantly decreased SCD1 mRNA expression by 88% in foam cells. ALA protein also was reduced by ALA treatment tested by western blot. In addition, ALA treatment induced a small yet significant increase of cholesterol efflux in foam cells. An increased cholesterol efflux also was observed in SCD1 knock down macrophage stable cell line. In overexpression SCD1 macrophage stable cell line, the cholesterol efflux was significantly decreased. We conclude that ALA increases cholesterol efflux via inhibition of SCD1 and would be beneficial to atherosclerosis regression via increasing efflux from lipid ladened foam cell.

Topical Omega-3 and Omega-6 Fatty Acids for Treatment of Dry Eye

To study the efficacy of topical application of alpha-linolenic acid (ALA) and linoleic acid (LA) for dry eye treatment. Formulations containing ALA, LA, combined ALA and LA, or vehicle alone, were applied to dry eyes induced in mice. Corneal fluorescein staining and the number and maturation of corneal CD11b(+) cells were determined by a masked observer in the different treatment groups. Real-time polymerase chain reaction was used to quantify expression of inflammatory cytokines in the cornea and conjunctiva. Dry eye induction significantly increased corneal fluorescein staining; CD11b(+) cell number and major histocompatibility complex Class II expression; corneal IL-1alpha and tumor necrosis factor alpha (TNF-alpha) expression; and conjunctival IL-1alpha, TNF-alpha, interferon gamma, IL-2, IL-6, and IL-10 expression. Treatment with ALA significantly decreased corneal fluorescein staining compared with both vehicle and untreated controls. Additionally, ALA treatment was associated with a significant decrease in CD11b(+) cell number, expression of corneal IL-1alpha and TNF-alpha, and conjunctival TNF-alpha. Topical ALA treatment led to a significant decrease in dry eye signs and inflammatory changes at both cellular and molecular levels. Topical application of ALA omega-3 fatty acid may be a novel therapy to treat the clinical signs and inflammatory changes accompanying dry eye syndrome.

Inflammatory status modifies the actions of n3 fatty acids on vascular function

We examined the postprandial effects of 3 meals containing unsaturated fatty acids on flow mediated dilation (FMD), serum fatty acids, and inflammatory biomarkers (CRP, Il-6, TNF-alpha) in individuals with type 2 diabetes (n=15) at baseline and 4h after the meals. The monounsaturated fatty acid (MUFA) meal contained 50 g fat from high oleic safflower and canola oils. Two additional meals were prepared by replacing 7% to 8% of MUFA with docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) from fish oil, or alpha-linolenic acid (ALA) from canola oil. In individuals with elevated baseline CRP, change in FMD after the fish oil meal was positively correlated with change in CRP, such that larger increases in CRP were associated with larger improvements in vascular function. However, during the ALA treatment, this group exhibited an inverse relationship between change in FMD and CRP. For subjects with low fasting CRP, CRP response to the ALA meal was positively correlated with FMD response. Changes in FMD and CRP were unrelated during the MUFA meal. In subjects with elevated baseline CRP, FMD response to the n3 meals was proportional to EPA, DHA, total n3, and the ratio of n3 to omega-6. FMD response was inversely correlated with the ratio of arachidonic acid (AA) to EPA. In conclusion, the specific effects of n3 fatty acids on vascular function appear to be dependent on background inflammatory status of individuals with type II diabetes.