Nonantioxidant Functions of α-Tocopherol in Smooth Muscle Cells

Azzi, Angelo; Breyer, Isabel; Feher, Maria; Ricciarelli, Roberta; Stocker, Achim; Zimmer, Sabine; Zingg, Jean‐Marc

doi:10.1093/jn/131.2.378s

Cited by 66 publications

(34 citation statements)

References 53 publications

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“…Vitamin E in LDL particles acts as a chain-breaking antioxidant, preventing lipid peroxidation of polyunsaturated fatty acids and modification of proteins by reactive oxygen species [26]. However, LDL is a major vehicle for vitamin E delivery to peripheral tissues [27] and AT availability for EC could differ according to in vivo experimental conditions, indicating that a direct action of AT on EC metabolism cannot be ruled out [28].…”

Section: Discussionmentioning

confidence: 99%

Dietary supplementation with vitamins C and E prevents downregulation of endothelial NOS expression in hypercholesterolemia in vivo and in vitro

Rodríguez¹,

Grau²,

Eguinoa³

et al. 2002

Atherosclerosis

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Impaired endothelium-dependent vasodilation has been associated with decreased NO bioavailability in hypercholesterolemia. This study aimed to determine whether antioxidant vitamins C and E could improve hypercholesterolemia-derived endothelial dysfunction in the porcine model, and whether observed in vivo results could be reproduced in vitro by incubation of coronary endothelial cells (EC) in the presence of native low-density lipoproteins (LDL). Adult mini-pigs were fed standard (C), cholesterol rich (HC) or cholesterol rich diet supplemented with vitamins C and E (HCV). Endothelium-dependent blood flow increase in response to acetylcholine was determined. Endothelial nitric oxide synthase (eNOS) expression was measured in arterial samples and in EC incubated with LDL isolated from porcine plasma. Vasomotor response to acetylcholine in HC was significantly lower (P B/ 0.05) than control and HCV. There was a significant (P B/0.05) decrease in eNOS immunoreactivity in HC, compared with HCV and control. Native LDL from HC, but not from HCV, induced a significant decrease in eNOS expression. Vitamins C and E treatment improved the endothelium-dependent vasomotor capacity and prevented decreased expression of eNOS in hypercholesterolemic pigs. A similar effect could be demonstrated in vitro, by incubation of EC with native LDL, suggesting that the effect of physiologically-modified LDL on eNOS could have a role in recovering vascular function. #

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Section: Discussionmentioning

confidence: 99%

Dietary supplementation with vitamins C and E prevents downregulation of endothelial NOS expression in hypercholesterolemia in vivo and in vitro

Rodríguez¹,

Grau²,

Eguinoa³

et al. 2002

Atherosclerosis

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“…The reduction in atherosclerosis associated with the high levels of arterial ␣-tocopherol is consistent with the antioxidant hypothesis. However, several studies show that ␣-tocopherol may modulate certain enzyme activities like the cholesterol ester exchange protein (2,63), PKC (61,102,103), and SR-B1 (72). Therefore, ␣-tocopherol affects biochemical pathways at the level of signaling and control in addition to its suggested role as an antioxidant (104,105).…”

Section: Discussionmentioning

confidence: 99%

α-Tocopherol protects against diet induced atherosclerosis in New Zealand white rabbits

Schwenke

Rudel

Sorci‐Thomas

et al. 2002

Journal of Lipid Research

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In this study, we asked the question "does ␣ -tocopherol supplementation prevent an increase in total plasma cholesterol (TPC) concentration and reduce the deposition of cholesterol in arterial plaques of rabbits fed atherogenic diets?" Isocaloric diets containing 0.1% cholesterol to induce atherosclerosis were enriched in one of three fats: saturated fats (SAT), monounsaturated fats (MONO), or n-6 polyunsaturated fats (POLY). Half of each of the three diets were supplemented with 2,500 IU ␣ -tocopherol/kg-diet. Unsupplemented diets contained 25 IU ␣ -tocopherol/kg-diet. Rabbits supplemented with ␣ -tocopherol had plasma ␣ -tocopherol concentrations 10-fold higher and an average TPC concentration 31% lower, P ‫؍‬ 0.017, than rabbits fed unsupplemented diets. Among the three fat-fed groups, the difference was greatest for the POLY fat fed group (54%, P ‫؍‬ 0.041). POLY fat-fed rabbits without ␣ -tocopherol supplementation had plasma HDL cholesterol concentrations that were less than half that of rabbits fed other fats, P р 0.0001. In general, differences in mean esterified artery cholesterol concentrations among the three fat-fed groups, with and without ␣ -tocopherol supplementation, paralleled differences in TPC concentration among the groups.This study suggests that for rabbits fed high pharmacological doses of ␣ -tocopherol, atherosclerosis can be diminished in situations where the plasma cholesterol concentrations are also significantly lower. -Schwenke, D. C., L. L. Rudel, M. G. Sorci-Thomas, and M. J. Thomas. ␣ -Tocopherol protects against diet induced atherosclerosis in New Zealand white rabbits.

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“…Sejumlah penelitian lain juga menunjukkan adanya efek penghambatan PKC pada sel makrofag, neutrophil, fibroblas dan sel mesangial oleh -tocopherol [24]. Sedangkan minyak wijen tidak mempunyai efek antiproliferasi.…”

Section: Pembahasanunclassified

Proteksi Kombinasi Minyak Wijen dan α-tocopherol Terhadap Glomerular Injury Melalui Penghambatan Stres Oksidatif Tikus Hiperkolesterolemia

Sukmawati

2013

JELS

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AbstrakMinyak wijen (MW) kaya akan polyunsaturated fatty acid (PUFA) terutama linoleat yang diketahui dapat menurunkan kadar lipid dalam darah. Namun, salah satu kelemahan PUFA sebagai hipolipidemik adalah cenderung mudah untuk teroksidasi karena struktur ikatan rangkapnya. Vitamin E (α-tocopherol) diketahui dapat melindungi struktur PUFA terhadap oksidasi serta dapat menghambat stres oksidatif. Peningkatan stres oksidatif pada hiperkolesterolemia diduga kuat berperan penting dalam patogenesa glomerular injury. Tujuan penelitian ini untuk membuktikan bahwa penambahan α-tocopherol pada minyak wijen mempunyai efek sinergis dalam mencegah glomerular injury melalui penurunan stres oksidatif. Penelitian ini menggunakan Rattus novergicus strain Wistar jantan (200 g) yang dibagi menjadi tujuh kelompok masing -masing 4 ekor, kelompok hiperkolesterol (HK), kelompok ke-2, ke-3 dan ke-4 adalah kelompok HK + MW (dosis masing-masing 0,3; 0,6, dan 1,2 ml), sedangkan kelompok ke-5, ke-6 dan ke-7 adalah kelompok HK + MW (dosis masing -masing 0.3, 0.6 dan 1.2 ml) + α-tochopherol 20 mg). Pengukuruan kadar kolesterol total, Low Density Lipoprotein (LDL), ureum dan kreatinin darah dilakukan pada minggu ke-10. Aktivitas stres oksidatif jaringan ginjal diukur dari kadar malondialdehide (MDA) menggunakan uji thiobarbituric acid (TBA) dan kadar superoxyde dismutase (SOD) jaringan dengan uji Nitroblue tetrazolium (NBT). Pemeriksaan histologis dilakukan untuk melihat deposit matriks dan jumlah sel mesangial pada glomerulus dengan pengecatan Periodic Acids Schiff (PAS). Hasil penelitian ini menunjukkan adanya perbedaan bermakna penurunan kadar MDA antara kelompok MW dengan MW + α-tocopherol pada dosis 0.3 (p = 0.000) dan 0.6ml (p = 0.001) yang menunjukkan interaksi sinergistik MW + α-tocopherol serta kecenderungan penurunan kadar SOD. Terdapat dugaan interaksi secara potensiasi dengan penambahan α-tocopherol pada minyak wijen terhadap penurunan kadar kolesterol total dan LDL. Gambar histologis glomerular injury menunjukkan bahwa kombinasi MW + α-tocopherol dapat menghambat peningkatan jumlah sel (p = 0.000) dan matriks mesangial (p = 0.614). Hasil ini menunjukkan bahwa penambahan α-tochopherol pada minyak wijen mempunyai efek yang lebih baik dibanding minyak wijen sendiri dalam menghambat glomerular injury melalui penghambatan stres oksidatif di jaringan ginjal secara sinergis.Kata kunci: α-tocopherol, glomerular injury, minyak wijen, stres oksidatif. Abstract Sesame oil is rich of polyunsaturated fatty acid (PUFA) especially linoleic acid which is known to reduce lipid content in blood. However, one susceptibility of PUFA as hypolipidemic is it tends to be oxidized because of its double bond structure. Vitamin E (α-tocopherol) was known to protect the structure of PUFA towards oxidation and inhibit oxidative stress. The increase of oxidative stress on hypercholesterolemia is strongly expected to have important role in pathogenesis of glomerular injury. This study aimed to assess the addition of α-tocopherol on sesame oil that has the ef...

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Nonantioxidant Functions of α-Tocopherol in Smooth Muscle Cells

Cited by 66 publications

References 53 publications

Dietary supplementation with vitamins C and E prevents downregulation of endothelial NOS expression in hypercholesterolemia in vivo and in vitro

Dietary supplementation with vitamins C and E prevents downregulation of endothelial NOS expression in hypercholesterolemia in vivo and in vitro

α-Tocopherol protects against diet induced atherosclerosis in New Zealand white rabbits

Proteksi Kombinasi Minyak Wijen dan α-tocopherol Terhadap Glomerular Injury Melalui Penghambatan Stres Oksidatif Tikus Hiperkolesterolemia

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