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Title
Effect of chronic ethanol feeding on glutathione and functional
integrity of mitochondria in periportal and perivenous rat hepatocytes.
Author
Garc]ia-Ruiz C; Morales A; Ballesta A; Rod]es J; Kaplowitz N;
Fern]andez-Checa JC
Address
Hospital Clinic i Provincial' Departamento de Medicina' Universidad
de
Barcelona' Spain.
Source
J Clin Invest, 94(1):193-201 1994 Jul
Abstract
Chronic ethanol feeding selectively impairs the translocation
of
cytosol GSH into the mitochondrial matrix. Since ethanol-induced
liver
cell inJury is preferentially localized in the centrilobular
area' we
examined the hepatic acinar distribution of mitochondrial GSH
transport
in ethanol-fed rats. Enriched periportal (PP) and perivenous
(PV)
hepatocytes from pair- and ethanol-fed rats were prepared as
well as
mitochondria from these cells. The mitochondrial pool size of
GSH was
decreased in both PP and PV cells from ethanol-fed rats either
as
expressed per 10(6) cells or per microliter of mitochondrial
matrix
volume. The rate of reaccumulation of mitochondrial GSH and the
linear
relationship of mitochondrial to cytosol GSH from ethanol-fed
mitochondria were lower for both PP and PV cells' effects observed
more
prominently in the PV cells. Mitochondrial functional integrity
was
lower in both PP and PV ethanol-fed rats' which was associated
with
decreased cellular ATP levels and mitochondrial membrane potential'
effects which were greater in the PV cells. Mitochondrial GSH
depletion
by ethanol feeding preceded the onset of functional changes in
mitochondria' suggesting that mitochondrial GSH is critical in
maintaining a functionally competent organelle and that the greater
depletion of mitochondrial GSH by ethanol feeding in PV cells
could
contribute to the pathogenesis of alcoholic liver disease.
Title
Prenatal exposure to ethanol in rats: effects on liver energy
level and
antioxidant status in mothers, fetuses, and newborns.
Author
Addolorato G; Gasbarrini A; Marcoccia S; Simoncini M; Baccarini
P;
Vagni G; Grieco A; Sbriccoli A; Granato A; Stefanini GF; Gasbarrini
G
Address
Institute of Internal Medicine, Catholic University, Rome, Italy.
Source
alcohol, 14(6):569-73 1997 Nov-Dec
Abstract
The fetal alcohol syndrome is a clinical condition that affects
newborns from alcoholic mothers. It is not clear, however, whether
ethanol consumption during gestation can affect liver functions
of
fetuses and newborns. In this study, we aimed to assess the effects
of
ethanol administration on body weight, liver energy level, and
antioxidant status of mothers, fetuses, and newborns. Pregnant
rats
were exposed to ethanol during the third week of gestation. Body
weight, survival, and liver concentration of gluthatione (GSH)
and
adenosintriphosphate (ATP) were measured. No differences were
observed
in body weight or in liver ATP and GSH between mothers exposed
to
ethanol and control animals. Conversely, fetuses from rats exposed
to
ethanol showed a marked decrease in GSH, ATP, and body weight
when
compared to those from control rats. Newborns exposed prenatally
to
ethanol were no different from those born to control mothers.
This
study suggests that an amount of ethanol that is not sufficient
to
determine a significant effect on mothers can, nevertheless,
cause a
marked decrease in growth and in liver antioxidant and energy
status in
fetuses. These parameters, however, return to control value one
week
after ethanol discontinuation.
Title
Acute ethanol administration induces oxidative changes in rat
pancreatic tissue.
Author
Altomare E; Grattagliano I; Vendemiale G; Palmieri V; Palasciano
G
Address
Institute of Clinica Medica I' University of Bari' Italy.
Source
Gut, 38(5):742-6 1996 May
Abstract
BACKGROUND--There is mounting clinical evidence that ethanol
toxicity
to the pancreas is linked with glutathione depletion from oxidative
stress but there is not experimental proof that this occurs.
AIMS AND
METHODS--The effect of acute ethanol ingestion (4 g/kg) on the
pancreatic content of reduced (GSH) and oxidised (GSSG) glutathione'
malondialdehyde (MDA)' and carbonyl proteins were therefore studied
in
the rat. RESULTS--ethanol caused a significant reduction in GSH
(p <
0.02) and an increase in GSSG (p < 0.005)' MDA (p < 0.05)'
and carbonyl
proteins (p < 0.05) in the rat pancreas. The GSH/GSSG ratios
were
significantly decreased after ethanol' especially in rats pretreated
with diethylmaleate (DEM)' a GSH blocker. Administration of ethanol
after DEM further increased the rate of lipid and protein oxidation.
Pretreatment with cyanamide (an inhibitor of aldehyde dehydrogenase)
but not with 4-methylpyrazole (an alcohol dehydrogenase inhibitor)
caused higher production of GSSG and MDA. CONCLUSIONS--These
findings
indicate that acute ethanol reduces the pancreatic content of
GSH'
which seems to be protective against ethanol toxicity' since
its
depletion is accompanied by increased oxidative damage to cell
structures. The further increase of lipid peroxidation and GSSG
production in the presence of cyanamide suggests that acetaldehyde
might be responsible for the oxidative changes that occur in
pancreatic
cells after ethanol administration.
Title
Influence of glutathione on the oxidation of
1-methyl-6-hydroxy-1'2'3'4-tetrahydro-beta-carboline: chemistry
of
potential relevance to the addictive and neurodegenerative consequences
of ethanol use.
Author
Han QP; Dryhurst G
Address
Department of Chemistry and Biochemistry' University of Oklahoma'
Norman' Oklahoma 73019' USA.
Source
J Med Chem, 39(7):1494-508 1996 Mar 29
Abstract
Recent evidence suggests that intraneuronal metabolism of ethanol
by
catalase/H2O2 and an ethanol-inducible form of cytochrome P450
together
generate acetaldehyde and oxygen radicals including the hydroxyl
radical (HO.). Within the cytoplasm of serotonergic neurons'
these
metabolic processes would thus provide acetaldehyde' which would
react
with unbound 5-hydroxytryptamine (5-HT) to give
1-methyl-6-hydroxy-1'2'3'4-tetrahydro-beta-carboline (1)' known
to be
formed at elevated levels in the brain following ethanol drinking'
and
HO. necessary to oxidize this alkaloid. In this study' it is
demonstrated that the HO.-mediated oxidation of 1 at physiological
pH
yields 1-methyl-1'2'3'4-tetrahydro-beta-carboline-5'6-dione (8)
that
reacts avidly with free glutathione (GSH)' a significant constituent
of
axons and nerve terminals' to give diastereomers of
8-S-glutathionyl-1-methyl-1'2'3'4-tetrahydro-beta-carboline-5'6-dione
(9A and 9B). In the presence of free GSH' ascorbic acid' other
intraneuronal antioxidants/reductants' and molecular oxygen
diastereomers' 9A/9B redox cycle in reactions that generate H2O2
and'
via trace transition metal ion catalyzed decomposition of the
latter
compound' HO.. Further reactions of 9A/9B with GSH and/or HO.
generate
several additional glutathionyl conJugates that also redox cycle
in the
presence of intraneuronal reductants and molecular oxygen forming
H2O2
and HO.. Thus' intraneuronal formation of 1 and HO. as a consequence
of
ethanol drinking and resultant endogenous synthesis of 8'9A'
and 9B
would' based on these in vitro chemical studies' be expected
to
generate elevated fluxes of H2O2 and HO. leading to oxidative
damage to
serotonergic axons and nerve terminals and the irreversible loss
of
GSH' both of which occur in the brain as a consequence of ethanol
drinking. Furthermore' deficiencies of 5-HT and loss of certain
serotonergic pathways in the brain have been linked to the preference
for and addiction to ethanol.
Title
ethanol-induced oxygen radical formation and lipid peroxidation
in rat
brain: effect of chronic alcohol consumption.
Author
Montoliu C; Vall]es S; Renau-Piqueras J; Guerri C
Address
Instituto de Investigaciones Citol]ogicas' Hospital La Fe' Valencia'
Spain.
Source
J Neurochem, 63(5):1855-62 1994 Nov
Abstract
The effect of chronic and in vitro ethanol exposure on brain
oxygen
radical formation and lipid peroxidation was analyzed. ethanol
induces
a dose-dependent increase in lipid peroxidation in brain homogenates.
The peroxidative effects of alcohol seem to be related to both
cytochrome P450 and the ethanol-inducible form of cytochrome
P450
(CYP2E1)' because preincubation with metyrapone (an inhibitor
of
cytochrome P450) or with an antibody against CYP2E1 abolished
the
ethanol-increased lipid peroxidation. Using the formation of
dichlorofluorescein' we also demonstrated that both in vitro
and
chronic alcohol exposure significantly enhanced the formation
of oxygen
radical species in synaptosomes. Chronic alcohol treatment also
leads
to an induction of cytochrome P450 (230%)' NADPH cytochrome c
reductase
(180%)' NADPH oxidation (184%)' and CYP2E1 in brain microsomes.
In
addition' this treatment produced a decrease in the GSH/GSSG
ratio in
brain and significantly enhanced the levels of superoxide dismutase
and
catalase activities. This mechanism could be involved in the
toxic
effects of ethanol on brain and membrane alterations occurring
after
chronic ethanol intake.
Title
Monitoring oxidative damage in patients with liver cirrhosis
and
different daily alcohol intake.
Author
Clot P; Tabone M; Aric`o S; Albano E
Address
Department of Experimental Medicine and Oncology' University
of Turin'
Italy.
Source
Gut, 35(11):1637-43 1994 Nov
Abstract
This study looked at the possible association between alcohol
abuse and
free radical mediated oxidative inJury by examining the presence
of
oxidative damage' as monitored by erythrocyte malonildialdehyde
and
plasma lipid hydroperoxides' in patients with liver cirrhosis
and
different lifetime daily alcohol intake. All patients with an
alcohol
intake above 100 g/day (ALC) showed concentrations of malonildialdehyde
and lipid hydroperoxide on average four to fivefold higher than
cirrhotic patients with alcohol intake below 100 g/day (NAC)
or healthy
controls. Further subgrouping of ALC patients showed that those
with
alcohol intake ranging between 100 and 200 g/day (ALC1) had
malonildialdehyde and lipid hydroperoxide concentrations significantly
lower than those with an intake higher than 200 g/day (ALC2).
These
differences were not related to the extent of liver inJury or
to the
liver derangement as assessed by Child`s classification. The
increase
in lipid peroxidation markers in ALC cirrhotic patients was associated
with a decrease in' respectively' plasma alpha-tocopherol and
erythrocyte glutathione concentrations. Significant differences
were
also seen between ALC1 and ALC2 groups in plasma alpha-tocopherol'
but
not in erythrocyte glutathione concentrations. The concentrations
of
alpha-tocopherol and glutathione in the blood of NAC patients
were in
contrast not substantially different from those of healthy controls.
The close association between oxidative damage and alcohol abuse
suggested that free radical intermediates produced during ethanol
metabolism might be responsible for causing oxidative damage.
Title
ethanol-induced oxidative stress and enzymatic defenses in cultured
fetal rat hepatocytes.
Author
Devi BG; Schenker S; Mazloum B; Henderson GI
Address
University of Texas Health Science Center at San Antonio' Department
of
Medicine 78284-7878' USA.
Source
alcohol, 13(4):327-32 1996 Jul-Aug
Abstract
Previously' we have documented an ethanol (E)-induced oxidative
stress
(OS) in cultured fetal rat hepatocytes (FRH). The cause of this
is
uncertain' but an inhibition of key antioxidant enzymes could
be a/the
factor. OS was also observed in fetal liver (FL) during in utero
E
exposure' but not in maternal liver' a difference that might
be related
to selectively lower enzymatic defenses in the fetus. Here' we
record
effects of E on activities of catalase (Cat)' superoxide dismutase
(Cu'
Zn SOD and Mn SOD)' glutathione peroxidase (GPX)' and
glutathione-S-transferase (GST) in FRH isolated from 20-day-old
fetuses
and exposed to E (2 mg/ml) for up to 24 h and we compare these
to adult
rat liver data. E treatment decreased fetal liver reduced glutathione
(GSH) pools by 23% (p < 0.05) and increased malondialdehyde
(MDA) by
14% (p < 0.05) within 24 h of E exposure. E caused an increase
in fetal
liver Cat by 18%' 32%' and 47% by 3' 6' and 24 h of E' respectively
(p
< 0.05). A 24-h E exposure increased Cu' Zn SOD by 22% (p
< 0.05) and
Mn SOD by 21% (p < 0.05). A 24 h E treatment increased GPX
by 18% (p <
0.05) and GST by 17% (p < 0.05). Cat in whole FL was 26% of
adult (p <
0.05) whereas Cu' Zn SOD and Mn SOD in whole FL were 12% and
11% of
adult levels (p < 0.05). GPX and GST in FL were 11% and 28%
of adult
values (p < 0.05). It is concluded that in FRH' E-induced
OS is not
caused by impaired activities of these enzymes' but their low
basal
activities (vs. adult) may predispose the fetus to OS.
Title
Oxidation of mitochondrial proteins and DNA following administration
of
ethanol.
Author
Wieland P; Lauterburg BH
Address
Department of Clinical Pharmacology' University of Bern' Switzerland.
Source
Biochem Biophys Res Commun, 213(3):815-9 1995 Aug 24
Abstract
Oxidation of mitochondrial DNA might be responsible for the persistence
of structural and functional abnormalities of mitochondria in
alcoholics after cessation of ethanol intake. ethanol (4g/kg)
was
administered to mice' and DNA was isolated 3 h later from liver
homogenates and mitochondria. ethanol resulted in a 25% decrease
of GSH
in liver homogenates without increase in GSSG' oxidized proteins
and
8-OHdG' respectively. In contrast' the content of carbonyls (23
+/- 1
vs 9 +/- 1 nmol/mg protein) and the extent of oxidation of DNA
(49 +/-
8 vs 17 +/- 3 8-OHdG/10(5) dG) were significantly increased in
mitochondria. Depletion of GSH with diethyl maleate also resulted
in a
2-3 fold increase in the oxidation of proteins and DNA in mitochondria
exclusively. Oxidation of DNA and low GSH together with the lack
of DNA
repair enzymes may result in permanent damage to the mitochondria
of
alcoholic subJects.
Title
Hepatic and metabolic effects of ethanol: pathogenesis and prevention.
Author
Lieber CS
Address
alcohol Research and Treatment Center' Bronx VA Medical Center'
New
York 10468.
Source
Ann Med, 26(5):325-30 1994 Oct
Abstract
Mechanisms of the hepatotoxicity of ethanol are reviewed' including
effects resulting from alcohol dehydrogenase (ADH) mediated excessive
hepatic generation of NADH and acetaldehyde. Gastric ADH explains
first-pass metabolism by ethanol; its activity is low in alcoholics
and
in females and is decreased by some commonly used drugs. In addition
to
ADH' ethanol can be oxidized by liver microsomes: studies over
the last
25 years have culiminated in the molecular elucidation of the
ethanol-inducible cytochrome P-450 (2E1) which causes metabolic
tolerance to ethanol and to various commonly used medications'
enhanced
degradation of testosterone and vitamin A (with vitamin A depletion)
and selective hepatic perivenular toxicity. The latter results
from
free radical generation and activation of various xenobiotics'
causing
increased vulnerability of the heavy drinker to the toxicity
of
industrial solvents' anaesthetic agents' commonly prescribed
drugs'
over-the-counter analgesics' chemical carcinogens and even nutritional
factors such as vitamin A and beta-carotene. Furthermore' induction
of
the microsomal pathway contributes to increased acetaldehyde
generation
which promotes GSH depletion and lipid peroxidation and other
toxic
effects. Nutritional deficits may affect the toxicity of ethanol
and
acetaldehyde' as illustrated by the depletion in glutathione'
ameliorated by S-adenosyl-L-methionine. Other `supernutrients`
include
polyenylphosphatidylcholine' shown to correct the alcohol-induced
hepatic phosphatidylcholine depletion and to prevent alcoholic
cirrhosis in non-human primates.
Title
Lipid hydroperoxide induced mitochondrial dysfunction following
acute
ethanol intoxication in rats. The critical role for mitochondrial
reduced glutathione.
Author
Masini A; Ceccarelli D; Gallesi D; Giovannini F; Trenti T
Address
Istituti di Patologia Generale' Universit`a di Modena' Italy.
Source
Biochem Pharmacol, 47(2):217-24 1994 Jan 20
Abstract
It has been found that acute ethanol (EtOH) intoxication of rats
caused
depletion of mitochondrial reduced glutathione (GSH) of approximately
40%. A GSH reduction of similar extent was also observed after
the
administration to rats of buthionine sulphoximine (BSO)' a specific
inhibitor of GSH synthesis. Combined treatment with BSO plus
EtOH
further decreased mitochondrial GSH up to 70% in comparison to
control.
Normal functional efficiency was encountered in BSO-treated
mitochondria' as evaluated by membrane potential measurements
during a
complete cycle of phosphorylation. In contrast a partial loss
of
coupled functions occurred in mitochondria from EtOH- and BSO
plus
EtOH-treated rats. The presence in the incubation system of either
GSH
methyl monoester (GSH-EE)' which normalizes GSH levels' or of
EGTA'
which chelates the available Ca2+' partially restores the mitochondrial
phosphorylative efficiency. Following EtOH and BSO plus EtOH
intoxication' the presence of fatty-acid-conJugated diene
hydroperoxides' such as octadecadienoic acid hydroperoxide (HPODE)'
was
detected in the mitochondrial membrane. Exogenous HPODE' when
added to
BSO-treated mitochondria' induced' in a concentration-dependent
system'
membrane potential derangement. The presence of either GSH-EE
or EGTA
fully prevented a drop in membrane potential. The results obtained
suggest that fatty acid hydroperoxides' endogenously formed during
EtOH
metabolism' brought about non-specific permeability changes in
the
mitochondrial inner membrane whose extent was strictly dependent
on the
level of mitochondrial GSH. |
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