1-4
5-8
9-12
13-16
17-20
21-24
25-28
29-32
33-36
37-40
41-44
mg/kg all p<0.0001). This naltrexone effect is similar to that observed in the alcohol
deprivation effect and extinction-reinstatement models. Therefore, this simple model
can be used to test new compounds and study craving mechanisms.
ACATALASEMIC AND NORMAL MICE
2, T.I. Khomich1, S.M. Zimatkin2and R.
Deitrich3
Institute of Biochemistry, NAS, Grodno, Belarus, 2Grodno State Medical University,
Grodno, Belarus, 3University of Colorado, Denver, Co, USA
many neuropharmacologic and behavioural effects of ethanol (Zimatkin and Deitrich,
1997). As is known, catalase is one of the enzymes oxidizing ethanol to acetaldehyde
in the brain. It was shown earlier that acatalasemic mice differ from normal animals
not only in brain catalase activity, but also in behavioural effects in response to
ethanol administration. These findings confirm the role of catalase in modulation of
psychopharmacologic effects of ethanol (Aragon and Amit, 1993). Cytochrome P-
4502E1 (CYP2E1) is expressed in the rat brain and induced by ethanol, however, its
contribution as well as that of other cytochromes P-450s (CYPs) remain unknown
(Hedlund et al., 2001). The aim of the study was to determine the contribution of
catalase and CYP2E1 to the oxidation of ethanol by brain tissue in vitro, using the
mice genetically deficient in catalase and enzyme inhibitors.
Methods. Brain samples from acatalasemic (CH3A, n=6) and normal (CH3N, n=5)
mice obtained from the University of Colorado were used in this study. Acetaldehyde
and acetate production from ethanol (50 mM) by brain homogenates were measured
by gas chromatography. The brain homogenates were preincubated for 20 min with
the catalase inhibitor sodium azide (5 mM) or the CYP2E1 inhibitor diallyl sulfide
(DAS, 2 mM). Some of the samples were treated with the common inhibitor of CYPs,
carbon monoxide (CO).
Results. The activity of catalase in the brain of CH3A mice was significantly lower, as
compared to control (CH3N) mice (P<0.01). The acatalasemic mice oxidize ethanol to
acetaldehyde at a much lower rate, as compared to normal mice (Figure). The
production of acetate in the samples, which was formed as a result of acetaldehyde
oxidation by aldehyde dehydrogenase, was 2-fold reduced in CH3A animals in
comparison with CH3N mice.
The catalase inhibitor sodium azide inhibited acetaldehyde production from ethanol in
brain homogenates by 90% in CH3A mice and by 70% in normal animals (P<0.05
and P<0.01, respectively, compared to the initial levels, Figure) and the difference
between the two groups after the treatment was also significant. The treatment of the
samples by CO inhibited ethanol oxidation by 58% in CH3A and by 73% in CH3N
mice (P<0.01 in both groups). DAS diminished the production of acetaldehyde by
62% (P<0.01 in both groups). Sodium azide as well as DAS and CO decreased the
acetate accumulation by 30-50% both in CH3A and CH3N homogenates.
Discussion. The differences in ethanol metabolism by brain tissue from acatalasemic
and normal mice, as well as the significant inhibition of this process by sodium azide
confirm the important role of catalase in the oxidation of ethanol in the mouse brain.
However, the pronounced inhibition of ethanol oxidation in the brain homogenates by
CO and DAS both in acatalasemic and control mice also suggests participation of
CYP2E1 and possibly some other isozymes of CYP in mouse brain ethanol
metabolism.
acatalasemic mice: systematic examination using a biobehavioral approach. Pharmacol.
Biochem. Behav. 44, 547-554.
Hedlund, E., Gustafsson, J.-A. and Warner, M. (2001) Cytochrome P450 in the brain; a
review. Current Drug Metab. 2, 245-263.
Zimatkin S.M.and Deitrich R.A. (1997) Ethanol metabolism in the brain. Addiction Biol. 2,
387-392.
OF ETHANOL INTAKE IN AA RATS
1, Petri Hyytiä2, Ingrid Nylander1
Sweden, 2Department of Mental Health and Alcohol Research, National Public Health Institute,
Helsinki, Finland
voluntary ethanol intake, have altered basal levels of endogenous opioid peptides in
various brain areas and that neonatal manipulation could induce long-lasting effects
on endogenous opioid peptides. The purpose of this study was to investigate whether
neonatal manipulation during postnatal days 1-21 could affect initiation and
maintenance of voluntary ethanol intake in alcohol-preferring male AA rats.
The rat pups were exposed to 15 min (MS15) or 360 min (MS360) of maternal
separation, respectively, for the first three weeks of life, or exposed to normal animal
facility rearing (AFR). As adults, the male rats were gradually introduced to
increasing concentrations of ethanol.
Comparisons of the ethanol drinking patterns show that MS15 rats reached a high,
stable voluntary ethanol intake later than MS360 and AFR rats. The MS15 rats had a
significantly lower ethanol intake (8% ethanol) compared to both MS360 and AFR
rats and also a significantly lower ethanol preference than MS360 rats, but not
compared to AFR rats.
The results from the present study indicate that 15 min of maternal separation can
decrease voluntary ethanol intake and ethanol preference in male AA rats, selected for
a high ethanol intake. Therefor, 15 min of maternal separation is suggested to protect
against high voluntary ethanol intake later in life.
EFFECT IN ALCOHOL-PREFERRING sP RATS
1,2, Giuliana Brunetti1,2, Giovanni Vacca1,2, Carla Lobina1,2,
Mauro A.M. Carai1, Giancarlo Colombo2, Gian Luigi Gessa1-3
Cagliari, Italy; 3“Bernard B. Brodie” Department of Neuroscience, University of Cagliari, Cagliari,
Italy.
and maintenance of alcohol drinking behavior in selectively bred Sardinian alcohol-
baclofen on alcohol intake to the so-called alcohol deprivation effect (ADE), a model
of relapse drinking in human alcoholics. ADE is defined as a marked, although
temporary, increase in alcohol intake after a period of alcohol withdrawal. Previous
work demonstrated that ADE is a rather robust phenomenon in sP rats.
In the present study, sP rats had unlimited access to 10% ethanol under the homecage
two-bottle choice regimen for 4 consecutive weeks. Subsequently, one group of rats
was deprived of alcohol for 15 consecutive days, during which water was the sole
fluid available (alcohol-deprived rats), while a second group continued to have
unlimited access to alcohol and water (alcohol-nondeprived rats). At the end of the
15th day of the deprivation phase, rats of both groups were injected i.p. with 0, 1, 1.7
or 3 mg/kg baclofen. Baclofen administration occurred 30 min before representation
of the alcohol bottle (which coincided with lights off).
Alcohol intake over the first hour of re-access was higher, by approximately 30%, in
alcohol-deprived than -nondeprived rats, respectively (Fig. 1), indicative of the
development of ADE. Pretreatment with baclofen resulted in a dose-dependent,
complete abolishment of ADE (Fig. 1).
The results of the present study suggest that the GABABreceptor may be part of the
neural substrate mediating ADE. Further, these results suggest that baclofen may
possess anti-relapse properties.
Each bar is the mean ± S.E.M. of n=8 *P<0.05 with respect to alcohol-nondeprived
rats receiving 0 mg/kg baclofen (Newman-Keuls test); +P<0.05 with respect to
alcohol-deprived rats receiving 0 mg/kg baclofen (Newman-Keuls test).