Prevention of glomerular dysfunction in diabetic rats by treatment
Koya D; Lee IK; Ishii H; Kanoh H; King GL
Research Division' Joslin Diabetes Center' Boston' MA 02215'
J Am Soc Nephrol, 8(3):426-35 1997 Mar
Because d-alpha-tocopherol (vitamin E) has been shown to decrease
diacylglycerol (DAG) levels and prevent the activation of protein
kinase C (PKC)' which is associated with retinal and renal dysfunctions
in diabetes' the study presented here characterized the effect
d-alpha-tocopherol treatment to prevent glomerular hyperfiltration
increased albuminuria as well as PKC activities in streptozotocin
(STZ)-induced diabetic rats. Two weeks after the induction of
total DAG content and PKC activity in glomeruli were significantly
increased in diabetic rats by 106.4 +/- 16.8% and 66.4 +/- 8.4%'
respectively' compared with control rats. Intraperitoneal inJection
d-alpha-tocopherol (40 mg/kg of body weight) every other day
the increases in total DAG content and PKC activity in glomeruli
diabetic rats. Glomerular filtration rate (GFR) and filtration
(FF) were significantly elevated to 4.98 +/- 0.34 mL/min and
0.05' respectively' in diabetic rats' compared with 2.90 +/-
mL/min and 0.25 +/- 0.02' respectively' in control rats. These
hemodynamic abnormalities in diabetic rats were normalized to
0.09 mL/min and 0.24 +/- 0.01' respectively' by d-alpha-tocopherol.
Albuminuria in 10-wk diabetic rats was significantly increased
+/- 2.2 mg/day compared with 1.2 +/- 0.3 mg/day in control rats'
whereas d-alpha-tocopherol treatment improved albumin excretion
2.4 +/- 0.6 mg/day in diabetic rats. To clarify the mechanism
d-alpha-tocopherol`s effect on DAG-PKC pathway' the activity
protein levels of DAG kinase alpha and gamma' which metabolize
phosphatidic acid' were examined. Treatment with d-alpha-tocopherol
increased DAG kinase activity in the glomeruli of both control
diabetic rats' by 22.6 +/- 3.6% and 28.5 +/- 2.3% respectively'
although no differences were observed in the basal DAG kinase
between control and diabetic rats. Because immunoblotting studies
not exhibit any difference in the protein levels of DAG kinase
and gamma' the effect of d-alpha-tocopherol is probably modulating
enzyme kinetics of DAG kinase. These findings suggest that the
increases in DAG-PKC pathway play an important role for the development
of glomerular hyperfiltration and increased albuminuria in diabetes
that d-alpha-tocopherol treatment could be preventing early changes
diabetic renal dysfunctions by normalizing the increases in DAG
levels in glomerular cells.
Bioavailability of various vitamin E compounds for finishing
Anderson LE Sr; Myer RO; Brendemuhl JH; McDowell LR
Animal Science Department' University of Florida' Gainesville
J Anim Sci, 73(2):490-5 1995 Feb
Relative bioavailabilities of four chemical forms of vitamin
evaluated when supplemented in diets of finishing swine for 28
crossbred pigs (80 kg)' individually penned' were divided equally
five treatments. Treatments consisted of corn soybean meal-based
supplemented with DL-alpha-tocopherol' DL-alpha-tocopheryl acetate'
D-alpha-tocopherol' or D-alpha-tocopheryl acetate. A treatment
vitamin E supplementation (negative control) served as the fifth
treatment. Each compound was supplemented at 62 IU/kg of diet.
samples were collected on d 0' 1' 2' 7' 14' 21' and 28. On d
the pigs were slaughtered to obtain tissue samples. Feed samples'
from feeders' were also collected on d 0' 5' 14' and 21. All
forms fed increased (P < .01) serum alpha-tocopherol by d
2 and peaked
by d 7. Serum alpha-tocopherol in pigs fed either acetate form
elevated beyond d 7; serum alpha-tocopherol steadily declined
lower (P < .01) on d 14' 21' and 28 in pigs fed either alcohol
compared with concentrations in the acetate-fed pigs. The decrease
probably a reflection of poor stability of the alcohol forms
in the feed; the acetate forms were found to be stable in the
the 28-d study. Dietary supplementation of D-alpha-tocopheryl
resulted in the highest serum alpha-tocopherol throughout the
similar trend was observed in tissue (liver' backfat' leaf fat'
semimembranosus' rhomboideus) alpha-tocopherol and serum: the
the highest concentration.(Abstract TRUNCATED AT 250 WORDS)
Bioavailability of alpha-tocopherol fed with retinol and relative
bioavailability of d-alpha-tocopherol or DL-alpha-tocopherol
Eicher SD; Morrill JL; Velazco J
Kansas State University' Manhattan 66506-1600' USA.
J Dairy Sci, 80(2):393-9 1997 Feb
Two experiments were conducted to examine the effects of the
alpha-tocopherol or interactions of alpha-tocopherol with vitamin
its bioavailability. In Experiment 1' Holstein steers were fed
that was low in vitamins A and E for 1 mo; then' steers were
body weight (X = 97.5 kg) and assigned randomly to one of four
treatments: 1) no added vitamins' 2) 442 mg of retinyl acetate'
mg of D-alpha-tocopherol' or 4) 442 mg of retinyl acetate and
of d-alpha-tocopherol. Each treatment was given as a pulse dose.
was sampled over a 36-h period. Concentrations of plasma retinyl
palmitate peaked at 2 to 6 h postsupplementation for all calves
then peaked again at 22 to 28 h for calves receiving vitamin
supplements. Concentrations of plasma alpha-tocopherol peaked
with d-alpha-tocopherol supplementation alone at 12 to 20 h after
supplementation' but simultaneous supplementation with retinyl
resulted in lower plasma alpha-tocopherol concentrations. Plasma
retinyl palmitate decreased during peak alpha-tocopherol
concentrations. In Experiment 2' blood and tissue were analyzed
single gastric tube administration of a powder (DL-alpha-tocopheryl
acetate) or a liquid (d-alpha-tocopherol) form of vitamin E to
calves. Plasma and kidney concentrations of alpha-tocopherol
higher when calves were fed d-alpha-tocopherol than when calves
fed the DL-alpha-tocopherol acetate form. Concentrations in the
spleen' adipose tissue' heart' muscle' cellular blood fraction'
did not differ between the two forms.
d-alpha-tocopherol inhibition of vascular smooth muscle cell
proliferation occurs at physiological concentrations' correlates
protein kinase C inhibition' and is independent of its antioxidant
Tasinato A; Boscoboinik D; Bartoli GM; Maroni P; Azzi A
Institut f ur Biochemie und Molekularbiologie' Universit at Bern'
Proc Natl Acad Sci U S A, 92(26):12190-4 1995 Dec 19
d-alpha-Tocopherol' but not d-beta-tocopherol' negatively regulates
proliferation of vascular smooth muscle cells at physiological
concentrations. d-alpha-tocopherol inhibits protein kinase C
activity' whereas d-beta-tocopherol is ineffective. Furthermore
d-beta-tocopherol prevents the inhibition of cell growth and
activity caused by d-alpha-tocopherol. The negative regulation
d-alpha-tocopherol of PKC activity appears to be the cause and
effect of smooth muscle cell growth inhibition. d-alpha-tocopherol
not act by binding to PKC directly but presumably by preventing
activation. It is concluded that' in vascular smooth muscle cells'
d-alpha-tocopherol acts specifically through a nonantioxidant
and exerts a negative control on a signal transduction pathway
regulating cell proliferation.
Urinary excretion of thiobarbituric acid reactive substances
subJects supplemented with a high dose of d-alpha-tocopherol.
Kosugi H; Asano Y; Nagayama T; Beppu M; Kikugawa K
Ferris University' Yokohama' Japan.
Biol Pharm Bull, 18(9):1275-8 1995 Sep
The level of urinary thiobarbituric acid reactive substances
consisting of bound forms of malonaldehyde and' to a lesser extent'
other aldehydes is one of the indices of lipid peroxidation status.
Levels of urinary TBARS in healthy subJects before and after
supplementation with a high dose of d-alpha-tocopherol were measured
using high performance liquid chromatography. Four healthy Japanese
were given a supplement of 300 mg d-alpha-tocopherol/d' about
higher than the normal intake recommended' for a period of 50
of urinary TBARS (nmol/kg body weight.h) within-day' before and
supplementation with d-alpha-tocopherol' exhibited similar behavior
levels of daily urinary TBARS (nmol/kg body weight.d) were unchanged
d-alpha-tocopherol supplementation. These results indicate that
supplementation with a high dose of d-alpha-tocopherol does not
the level of urinary TBARS.
vitamin E prevents diabetes-induced abnormal retinal blood flow
diacylglycerol-protein kinase C pathway.
Kunisaki M; Bursell SE; Clermont AC; Ishii H; Ballas LM; Jirousek
Umeda F; Nawata H; King GL
Research Division' Joslin Diabetes Center' Boston' Massachusetts'
Am J Physiol, 269(2 Pt 1):E239-46 1995 Aug
We have characterized effects of d-alpha-tocopherol (vitamin
activation of protein kinase C (PKC) and diacylglycerol (DAG)
retinal tissues of diabetic rats and correlated its effects to
diabetes-induced changes in retinal hemodynamics. Membrane PKC
activities were increased by 71% in streptozocin-induced diabetic
compared with controls (P < 0.05). Western blot analysis showed
membrane PKC-beta II was increased by 133 +/- 5% (P < 0.05).
of d-alpha-tocopherol (40 mg/kg ip) every other day prevented
increases in membrane PKC specific activity and PKC-beta II protein
immunoblots. Diabetes-induced increases in DAG levels were also
normalized by d-alpha-tocopherol treatment of 2 wk duration.
Physiologically' angiographic abnormalities of retinal hemodynamics
based on computerized video-based fluorescein angiography and
associated with increases of DAG and membranous PKC levels were
prevented by d-alpha-tocopherol treatment in diabetic rats. The
of d-alpha-tocopherol on retinal vascular cells was also studied.
Exposure of retinal endothelial cells to 22 mM glucose for 3
increased total DAG and [3H palmitate-labeled DAG levels by 35
and 50 +/- 8% (P < 0.05)' respectively' compared with exposure
mM glucose. The presence of d-alpha-tocopherol (50 micrograms/ml)
prevented the increases in total DAG and [3H palmitate-labeled
levels in cells exposed to 22 mM glucose. These findings suggested
treatment with d-alpha-tocopherol can prevent diabetes-induced
abnormalities in rat retinal blood flow.(Abstract TRUNCATED AT
Biodiscrimination of the eight alpha-tocopherol stereoisomers
in preferential accumulation of the four 2R forms in tissues
Weiser H; Riss G; Kormann AW
F. Hoffmann-La Roche Ltd' Vitamins and Fine Chemicals' Research
Technology Development' Basel' Switzerland.
J Nutr, 126(10):2539-49 1996 Oct
According to the USP' 2R'4`R'8`R-alpha-tocopheryl acetate
(RRR-alpha-TAc) is 1.36 times more active than all-rac-alpha-tocopheryl
acetate (all-rac-alpha-TAc). The all-rac form contains 12.5%
the stereoisomers RRR' RRS' RSR' RSS' SSS' SSR' SRS and SRR'
display different biopotencies. In the present study' female
rats fed a
vitamin E-deficient diet were administered 0.82 mg of all-rac-alpha-TAc
or 0.60 mg of RRR-alpha-TAc daily for up to 90 d. alpha-Tocopherol
concentrations in liver' brain' adipose tissue and plasma were
significantly different among groups on treatment d 64 and 90.
equipotent dosages of all-rac-alpha-TAc or RRR-alpha-TAc resulted
equimolar alpha-tocopherol plasma and tissue concentrations.
comparison with rats administered tocopherol-free placebo showed
plasma and tissue alpha-tocopherol of alpha-TAc-treated rats
represented alpha-tocopherol uptake during the repletion period.
eight individual alpha-tocopherol stereoisomers in tissues and
were determined by chiral HPLC and capillary gas chromatography.
treated with all-rac-alpha-TAc preferentially accumulated the
alpha-tocopherol stereoisomers (15-22% each' sum of all 2R =
tissues and plasma. The remaining 14-30% were 2S stereoisomers
predominance of the SRS form. In conclusion' all-rac-alpha-TAc
administration led to the presence of all eight alpha-tocopherol
stereoisomers in rat liver' brain' adipose tissue and plasma.
2R stereoisomers including RRR-alpha-tocopherol were equally
significantly enriched. This confirmed that the configuration
at C-2 of
the alpha-tocopherol molecule has a maJor impact on stereoisomer
biodiscrimination. Furthermore' the results are in agreement
hypothesis that for alpha-tocopherol stereoisomers' biopotency
differences are related to corresponding differences of
alpha-Tocopheryl hemisuccinate administration increases rat liver
subcellular alpha-tocopherol levels and protects against carbon
Tirmenstein MA; Leraas TL; Fariss MW
Department of Pharmaceutical Sciences' College of Pharmacy and
Program in Pharmacology/Toxicology' Washington State University'
Pullman 99164-6510' USA.
Toxicol Lett, 92(1):67-77 1997 Jun 16
Rats were administered a series of tocopherol analogs 18 h prior
hepatotoxic dose of carbon tetrachloride (CCl4). Of the compounds
tested' only d-alpha-tocopheryl hemisuccinate (TS) provided significant
protection against CCl4-induced hepatotoxicity. No protection
observed with either d-alpha-tocopherol (alpha-T) or a tocopherol
succinate ether derivative' d-alpha-tocopheryloxybutyric acid
None of the tocopherol analogs significantly inhibited CYP2E1
as measured by oxidation of p-nitrophenol. Liver homogenates
subcellular fractions (cytosol' nuclei' plasma membranes' mitochondria
and microsomes) were collected 18 h after tocopherol analog
administration in the absence of CCl4. Homogenate and subcellular
alpha-T levels were not significantly increased following TSE
administration but were increased 2-3 fold following TS and alpha-T
administration. Total tocopherol levels (alpha-T+ TS + TSE) in
homogenates and subcellular fractions were highest in rats supplemented
with TS. In these animals' TS was detected in all subcellular
and total tocopherol levels were increased from 6-23 fold over
seen in controls and 2-9 fold over alpha-T treated rats. In vitro
studies in which liver homogenates and subcellular fractions
peroxidized with ascorbate and ADP/Fe suggest that increasing
alpha-T but not TS correlates with increased protection against
peroxidation. These results suggest that the ability of TS to
against CCl4-induced hepatotoxicity relates to its enhanced hepatic
accumulation and subsequent hydrolysis to alpha-T.
alpha-Tocopherol and trolox block the early intracellular events
and calcium rises) elicited by oxidized low density lipoproteins
cultured endothelial cells.
Mabile L; Fitoussi G; Periquet B; Schmitt A; Salvayre R;
Department of Biochemistry' Faculty of Medicine in Rangueil'
Paul Sabatier' Toulouse' France.
Free Radic Biol Med, 19(2):177-87 1995 Aug
Low-density lipoproteins (LDLs)' treated by UV-C radiations under
conditions permitting mildly oxidized LDL (6 +/- 2 nmol TBARS/mg
without maJor structural or functional alteration of apoB)' have
used for studying their cytotoxicity to cultured bovine aortic
endothelial cells and the cytoprotective effect of various analogs
alpha-tocopherol. Toxic doses of oxidized LDL evoked intracellular
events' such as cellular thiobarbituric acid reactive substances
(TBARS) and a sustained peak of [Ca2+ i (cytosolic calcium).
sustained [Ca2+ i peak seems to be directly involved in the genesis
cell inJury leading to cell death in contrast to cellular TBARS'
seems to be either an earlier step of signal transduction or
effect' as shown by inhibiting the [Ca2+ i rise by ethylene
glycol-O'O`-bis(amino ethyl)-N1N1N`1N`-tetraacetic acid (EGTA)
Just before the time of the [Ca2+ i peak. When alpha-tocopherol
trolox (a short-chain' water-soluble analog of alpha-tocopherol)
added to the culture medium simultaneously with oxidized LDL'
able to increase the resistance of endothelial cells against
cytotoxic effect of oxidized LDL' whereas alpha-tocopheryl acetate
alpha-tocopheryl succinate were almost completely ineffective
of the liberation of only very low levels of alpha-tocopherol.
exhibited a more potent cytoprotective effect than alpha-tocopherol
(IC50: 1 +/- 0.2 and 8 +/- 2 mumol/l for trolox and alpha-tocopherol'
respectively). As shown by preincubating cells with effective
concentrations of alpha-tocopherol or trolox' the cytoprotective
was completely independent of any inhibition of LDL oxidation
remanent for 2 d with alpha-tocopherol or for 3-4 d with trolox.
Cytoprotective concentrations of trolox and alpha-tocopherol
inhibit LDL uptake but acted at the cellular level by blocking
formation of cellular TBARS and the sustained [Ca2+ i peak as
potential relevance of these data in relation to the prevention
atherosclerosis is discussed.
Vitamin C nutriture has little short-term effect on vitamin E
concentrations in healthy women.
Jacob RA; Kutnink MA; Csallany AS; Daroszewska M; Burton GW
Western Human Nutrition Research Center' U.S. Department of
Agriculture' Agricultural Research Service' Presidio of San Francisco'
CA 94129' USA.
J Nutr, 126(9):2268-77 1996 Sep
To determine whether the postulated sparing effect of vitamin
ascorbic acid (AA) is important for human nutrition' we studied
E status in 20 healthy pre-menopausal women (age 20-43 y) with
low vitamin C intakes for 6 wk in a live-in metabolic unit. The
experimental diet contained no fruits and vegetables and provided
mg/d of AA (Recommended Dietary Allowance = 60 mg/d)' 3 mg/d
alpha-tocopherol (RDA = 10 mg/d) and 42 g/d of tocopherol-stripped
safflower oil to increase the vitamin E requirement. Half of
subJects revived a daily AA supplement of 495 mg (high AA group).
biochemical ascorbate deficiency was attained in the low AA group
indicated by plasma AA concentrations that reached the lower
normal by study d 15. Oral doses (20 mg) of hexadeuterated
RRR-alpha-tocopherol acetate (d6-alphaT) were given daily to
subJects on d 15-21. Measures of vitamin E status included d6-alphaT
and unlabeled alpha-tocopherol concentrations in plasma' platelets'
buccal cells and adipose. The levels of unlabeled alpha-tocopherol
decreased over time in plasma and platelets and were unchanged
buccal cells and adipose' but were not significantly affected
intake. Likewise' the rise and fall of plasma and platelet d6-alpha
and measures of lipid peroxidation' were not affected by AA intake.
Although vitamin C nutriture did not significantly affect vitamin
status within the 6-wk time period of this experiment' further
this question is warranted' because some of the present results
indicate a trend toward sparing of tissue tocopherol by high
Efficacy of dietary and inJected vitamin E for poults.
Soto-Salanova MF; Sell JL
Department of Animal Science' Iowa State University' Ames 50011-3150'
Poult Sci, 75(11):1393-403 1996 Nov
An experiment was conducted to compare the efficacy of two dietary
sources and an inJectable form of vitamin E (VE) to improve the
status of poults. Six of the treatments consisted of a factorial
arrangement of three concentrations and two sources of dietary
Turkeys in these treatments received 12' 80' or 150 IU of either
dl-alpha-tocopheryl acetate or d-alpha-tocopherol (d-alpha-TOC)/kg
diet. The seventh treatment consisted of a single subcutaneous
inJection of d-alpha-TOC at 1 d of age. Poults in this treatment
subcutaneously inJected in the dorsal area of the neck with 25
d-alpha-TOC' this amount being approximately equivalent to the
poults would consume if their diet was supplemented with 150
VE/kg during their 1st wk of life. Concentration' source' or
VE administration did not affect growth parameters' plasma creatine
kinase' plasma triglycerides' or liver lipid peroxidation as
by the thiobarbituric acid reactive substances assay (TBARS).
red blood cells (RBC)' and liver alpha-TOC decreased from hatching
14 d of age in poults fed either Source of VE. The use
of 80 or 150 IU
of dietary VE (either Source) reduced (P < 0.05) the
depletion of alpha-TOC at all ages and also reduced the susceptibility
of RBC to hemolysis. There was no effect of Source of
dietary VE on
concentration of alpha-TOC in plasma' RBC' or liver' or on RBC
hemolysis. Subcutaneous inJection of 25 IU of d-alpha-TOC at
increased (P < 0.05) alpha-TOC concentration until 7 d of
d-alpha-TOC inJection reduced (P < 0.05) RBC susceptibility
hemolysis through 21 d of age. Data showed that one single subcutaneous
inJection of 25 IU of d-alpha-TOC at 1 d of age was as effective
IU or more of dietary VE through 21 d to improve the alpha-TOC
Tocopherols and 6-hydroxy-chroman-2-carbonitrile derivatives
vascular smooth muscle cell proliferation by a nonantioxidant
Boscoboinik D; Ozer NK; Moser U; Azzi A
Institut f ur Biochemie und Molekularbiologie' Universit at Bern'
Arch Biochem Biophys, 318(1):241-6 1995 Apr 1
The effects of two groups of similar compounds' a series of tocopherols
and one of 6-hydroxy-chroman-2-carbonitrile' have been studied
vascular smooth muscle cells. A poor correlation has been found
antiproliferative and antioxidant properties of these molecules.
d-alpha-tocopherol inhibits cell proliferation' while
D-alpha-tocopherylquinone has been found neither to inhibit nor
activate. D-beta-Tocopherol' a poor inhibitor of smooth muscle
proliferation' has been shown to be capable of preventing and
the inhibition by d-alpha-tocopherol. It is concluded that the
tocopherols and carbonitrile derivatives tested here appear to
smooth muscle cell proliferation by a nonantioxidant mechanism.
competition between d-alpha-tocopherol and D-beta-tocopherol
the existence of a common binding site for the two molecules.