Effect of taurine on ethanol-induced changes in open-field locomotor activity

In the present investigation we questioned whether taurine antagonized the effects of ethanol on motor activity measured in the open field. Ten minutes following simultaneous administration (IP) of ethanol (1.0, 1.5, 2.0 and 2.5 g/kg) or saline and taurine (30, 45 and 60 mg/kg) or saline, mice were placed in open field chambers and locomotor activity was measured during a 10 min testing period. A significant interaction was found between taurine and ethanol. Taurine-treated mice displayed lower motor excitation with the 1.0 g/kg dose of ethanol than the saline group treated with the same dose of ethanol. However at the 2.0 g/kg ethanol dose, taurine-treated mice demonstrated higher motor activity than the saline treated mice, once again, treated with the same dose of ethanol. No differences in blood ethanol levels were observed between the two groups. In a second study, taurine administration (30, 45 and 60 mg/kg) did not show any effect ond-amphetamine-induced enhancement of locomotor activity (1, 2, and 3 mg/kg). Data from this study demonstrated an interaction between taurine and ethanol in their effect on locomotor activity in the open field.     

Mediation of acute ethanol-induced motor disturbances by cerebellar adenosine in rats

The possible involvement of brain adenosine in acute ethanol-induced motor incoordination (MI) and inhibition of spontaneous motor activity (SMA) was investigated in male Sprague-Dawley rats. Pretreatment with theophylline or 7-(2-chloroethyl)-theophylline, adenosine antagonists, markedly reduced ethanol-induced MI and inhibition of SMA during a 60 min test period compared with saline + ethanol group. On the contrary, pretreatment with (-)-N6(R-phenylisopropyl)adenosine (R-PIA), an adenosine agonist, or dilazep, an adenosine uptake blocker, markedly potentiated the ethanol-induced MI as well as inhibition of SMA in a 60 min test period compared with saline + ethanol group. No effect on motor coordination was seen when the drug pretreatment was not followed by ethanol. However, the adenosine agonists and antagonists did alter SMA when the pretreatment with these drugs was not followed by ethanol. Ethanol clearance was not altered by the drug pretreatment as blood ethanol levels were similar in all groups except for lower ethanol levels in the R-PIA-treated group. Adenosine A1 binding studies, using 3H-R-PIA as the radioligand and crude membrane preparation from cerebellar cortex, revealed an increase in Bmax with no significant change in Kd in ethanol-treated animals vs. saline control. Theophylline pretreatment prevented the increase in Bmax elicited by ethanol. Collectively, the data suggest that endogenous cerebellar adenosine may be a participating factor in ethanol-induced motor dysfunctions.     

Dizocilpine prevents the development of tolerance to ethanol-induced error on a circular maze test

Dizocilpine [(+)MK-801] and ketamine, in doses that disrupt learning and memory, also prevent the development of tolerance to the motor impairing effects of ethanol (EtOH). However, dizocilpine itself affects motor behavior. In order to separate the possible influence of these two effects on the development of tolerance to EtOH, food-reinforced performance on a circular maze test was used in two different experiments. EtOH alone (1.2 g/kg) tended to increase the error score and reduce number of runs per trial, running speed, and total distance run, but on chronic administration of EtOH, tolerance developed progressively to all these effects. Dizocilpine also increased the error score, but had a biphasic effect on measures of running: low and intermediate doses (0.009 and 0.075 mg/kg, IP) increased running distance, whereas a high dose (0.15 mg/kg) decreased running speed and distance. When combined with EtOH, dizocilpine tended to overcome the effect of EtOH on running activity, but not on error score. Chronically, dizocilpine (0.075 and 0.15 mg/kg) prevented the development of tolerance to the effect of EtOH on error score, even though the lower dose of dizocilpine permitted tolerance to the effects of EtOH on running. These results suggest that NMDA receptor antagonists selectively inhibit tolerance to cognitive effects of ethanol even when the antagonists do not affect motor performance.     

l-Cysteine reduces oral ethanol self-administration and reinstatement of ethanol-drinking behavior in rats

Our previous findings have shown that l-cysteine, a non essential amino acid, prevented ethanol (EtOH) induced conditioned place preference. The aim of the present study was to examine the effect of l-cysteine on the acquisition and maintenance of oral EtOH self-administration and on the reinstatement of EtOH-drinking behavior in Wistar rats. Rats were pretreated intraperitoneally with saline or l-cysteine (20 and 40 mg/kg) 30 min before each acquisition trial, in an operant nose-poking paradigm where they were given the opportunity to orally self-administer tap water or EtOH (5-10% v/v). Further, to evaluate if l-cysteine reduces the acquired oral EtOH self-administration, we carried out an independent experiment in which rats were trained to self-administer EtOH (10%); after all groups of rats developed similarly stable oral EtOH self-administration, the effect of l-cysteine (0, 40, 60, 80 and 100 mg/kg) was tested. An additional group of rats was pretreated with saline or l-cysteine (80 mg/kg) and tested on reinstatement after EtOH extinction and, at the end of last reinstatement session, were utilized to measure blood and brain EtOH levels. The animals that had access to EtOH solution discriminated between the active and inactive nose-pokes and showed rates of active nose-pokes significantly higher than the tap water group. Furthermore, rats self-administering EtOH (10%) also demonstrated extinction behavior and gradually reinstated active nose-poke responding when EtOH was reintroduced. l-cysteine reduced both the acquisition and maintenance of oral EtOH self-administration. The reduced reinstatement of EtOH-drinking behavior was paralleled by a significant reduction of EtOH intake and correlated with blood and brain EtOH levels. The efficacy of l-cysteine on the various phases of alcohol drinking in rats, could represent an interesting pharmacological approach and could open a new line of research for the development of therapies to reduce EtOH intake in alcoholic patients.     

Are some of the effects of ethanol mediated through NPY?

 Central administration of neuropeptide Y (NPY) in low concentrations has been shown to produce anxiolysis and suppression of locomotor activity, a behavioral profile not dissimilar to that of ethanol. The present study was conducted to ascertain whether NPY and ethanol have similar electrophysiological profiles and to evaluate the combined actions of NPY and ethanol. Eighty-five Wistar rats were stereotaxically implanted with electrodes aimed at dorsal hippocampus, amygdala, and frontal cortex. Rats were administered NPY [or saline (SAL)] intracerebroventricularly (ICV) whereas the doses of alcohol (or SAL) were given intraperitoneally (IP). Two doses of alcohol (0.75, 1.5 g/kg) and two doses of NPY (1, 3 nmol) were given alone and in combination. Drug effects were assessed using event related potentials (ERP) recorded in response to an auditory ”oddball” plus noise paradigm between 30 and 40 min post-drug. Multivariate analyses of variance (MANOVA) revealed that NPY produced a significant decrease in the amplitude and increase in the latency of the N1 component in cortex and a decrease in the amplitude of the P3 component in amygdala, but no overall effects in hippocampus. Ethanol produced identical effects to NPY on the N1 and P3 components of the ERP in cortex and amygdala. Combined administration of EtOH and NPY (1 nmol) produced effects equivalent to those seen following the higher doses of NPY (3 nmol) or EtOH (1.5 g/kg). These studies demonstrate that NPY and ethanol have a similar electrophysiological profile. In addition, the combined administration of NPY and ethanol produced additive effects. Received: 23 December 1997 / Final version: 9 May 1998     

Arginine-8-vasopressin potentiates acute ethanol intoxication.

AVP maintains ethanol (EtOH) tolerance after cessation of chronic EtOH treatment. However, the acute interaction of AVP and EtOH has not been well characterized. Rats were trained on a moving belt and the EtOH dose-response relationship (range 1.0-2.0 g/kg) was determined after pretreatment with saline, AVP (2.5-40 micrograms SC or 10 ng ICV), the AVP-V1 receptor antagonist [Des-Gly9,d(CH2)5(1),O-Et-Tyr2, Val4,Arg8]-vasopressin (10 ng ICV), or AVP in combination with the V1 antagonist. AVP produced a 16% decrease in the EtOH ED50 when given either SC or ICV; this decrease, which appears to represent true potentiation rather than additivity, was prevented by the preadministration of the V1 antagonist. Other rats were made EtOH-tolerant by 7 daily injections of either EtOH alone (1.8 g/kg IP) or EtOH (1.5 g/kg IP) + AVP (10 micrograms SC), followed by a practice session on the moving belt. In both sets of tolerant animals, AVP potentiation of acute EtOH effects was still seen on day 6. The mechanism of AVP potentiation of EtOH-induced impairment is unknown, but the failure of the V1 antagonist alone to alter the effect of EtOH suggests that endogenous AVP is not involved directly in modulating EtOH intoxication.     

Environmental variables differentially affect ethanol-stimulated activity in selectively bred mouse lines

Low doses of ethanol (EtOH) stimulate activity in an open field in many strains of laboratory mice. We are selectively breeding two lines of mice to exhibit a large (FAST) response on this test, and two other lines to exhibit a small (SLOW) response (Crabbe et al. 1987). The lines initially diverged in response to EtOH, but despite continued selection pressure, the difference between each pair of FAST and SLOW lines has not increased over generations as much as expected. Our practice has been to test animals on the 1st day after saline injection, and repeat the test after EtOH injection 24 h later. Lister (1987) recently demonstrated that the order in which an animal was exposed to EtOH and saline influenced the magnitude of the response to EtOH, with animals tested initially after EtOH having greater stimulation. Middaugh et al. (1987) recently demonstrated that the magnitude of EtOH stimulation was greater under conditions of relatively bright light than under dim light. Using non-selected Swiss mice, the current experiments essentially confirmed Lister's findings. Using FAST and SLOW mice, the predictions of both groups were tested. Both hypotheses were confirmed. Additionally, these experiments demonstrated that the magnitude of the difference between FAST and SLOW mice was greater under bright light than under dim light. The line difference was also greater when tested in the EtOH-Saline order. In experiments with Swiss mice, the possible role of peritoneal irritation in the EtOH effect was eliminated, and the optimal dose and time for demonstrating the effect was determined. These experiments confirm the importance of lighting condition, order of testing, dose, and route of administration in eliciting EtOH-stimulated open field activity in mice. They demonstrate a genotype-environment interaction, since the magnitude of difference between genetically selected lines varied as a function of the testing parameters chosen. Finally, they indicate that the differences between FAST and SLOW lines in sensitivity to EtOH generalizes to several environmental conditions. We interpret this to mean that the various EtOH-induced activation traits represented by these different environmental and testing conditions are genetically correlated.     

The effects of ethanol ingestion and repeated benzene exposures on benzene pharmacokinetics

Two groups of $\text{C57B1}\text{6J}$ mice were exposed to 300-ppm benzene vapor, 6 hr/day, 5 days/week for 20 exposures. One group received 10% ethanol (EtOH) in the drinking water commencing 20 hr prior to the initial exposure and continuing 5 days/week throughout the study. The second group received tap water. The uptake and clearance of benzene was followed in the blood during and after the 1st and 20th exposures. During the first benzene exposures, the mean steady state benzene concentrations in benzene/EtOH-treated mice and benzene/water-treated mice were 5.2 and 10.7 μg/ml, respectively. The mean elimination rate constants for the benzene/EtOH- and benzene/water-treated groups were 0.124 and 0.042 min^?1, respectively. By 20 exposures, the benzene/EtOH group showed no change in mean blood steady state concentration (Css); however, the Css of the benzene/water group was reduced to 7.9 μg/ml. The mean elimination rate constants for the two groups were not different after the 20th exposure. The benzene/water mice exhibited a shift from mono- to biexponential clearance between the 1st and 20th exposures. Monoexponential clearances were observed for the benzene/EtOH group at both time points. These results indicate that 1 day of 10% EtOH consumption causes dramatic effects on benzene kinetics. After 20 days of treatment, the benzene/water and benzene/EtOH animals are kinetically similar. These changes in kinetics can be explained by the ability of ethanol and benzene to alter benzene metabolism.     

FOS expression induced by an ethanol-paired conditioned stimulus

To identify brain areas involved in ethanol-induced Pavlovian conditioning, brains of male DBA/2J mice were immunohistochemically analyzed for FOS expression after exposure to a conditioned stimulus (CS) previously paired with ethanol (2 g/kg) in two experiments. Mice were trained with a procedure that normally produces place preference (Before: ethanol before the CS) or one that normally produces place aversion (After: ethanol after the CS). Control groups received unpaired ethanol injections in the home cage (Delay) or saline only (Na?ve). On the test day, mice were exposed to the 5-min CS 90 min before sacrifice. Before groups showed a conditioned increase in activity, whereas the After group showed a conditioned decrease in activity. FOS expression after a drug-free CS exposure was significantly higher in Before-group mice than in control mice in the bed nucleus of the stria terminalis (Experiment 1) and anterior ventral tegmental area (Experiments 1-2). Conditioned FOS responses were also seen in areas of the extended amygdala and hippocampus (Experiment 2). However, no conditioned FOS changes were seen in any brain area examined in After-group mice. Overall, these data suggest an important role for the mesolimbic dopamine pathway, extended amygdala and hippocampus in ethanol-induced conditioning.     

Glutathione depletion and recovery after acute ethanol administration in the aging mouse

Glutathione (GSH) plays an important role in the detoxification of ethanol (EtOH) and acute EtOH administration leads to GSH depletion in the liver and other tissues. Aging is also associated with a progressive decline in GSH levels and impairment in GSH biosynthesis in many tissues. Thus, the present study was designed to examine the effects of aging on EtOH-induced depletion and recovery of GSH in different tissues of the C57Bl/6NNIA mouse. EtOH (2-5 g/kg) or saline was administered i.p. to mice of ages 6 months (young), 12 months (mature), and 24 months (old); and GSH and cyst(e)ine concentrations were measured 0-24h thereafter. EtOH administration (5 g/kg) depleted hepatic GSH levels >50% by 6h in all animals. By 24h, levels remained low in both young and old mice, but recovered to baseline levels in mature mice. At 6h, the decrease in hepatic GSH was dose-dependent up to 3g/kg EtOH, but not at higher doses. The extent of depletion at the 3g/kg dose was dependent upon age, with old mice demonstrating significantly lower GSH levels than mature mice (P<0.001). Altogether these results indicate that aging was associated with a greater degree of EtOH and fasting-induced GSH depletion and subsequent impaired recovery in liver. An impaired ability to recover was also observed in young animals. Further studies are required to determine if an inability to recover from GSH depletion by EtOH is associated with enhanced toxicity.     

Acquisition of behaviourally augmented tolerance to ethanol and its relationship to muscarinic receptors

Two groups of adult male rats were injected daily with ethanol (1.5 g/kg IP in 15% w/v solution) either before (the behaviourally augmented tolerant group) or after (the physiologically tolerant group) being placed in operant chambers. The control groups received daily isotonic saline injections either before or after the operant task. When challenged with ethanol (2.5 g/kg) on day 30 prior to the operant task, the control group was most impaired, while the behaviourally augmented tolerant group was significantly less impaired than the physiologically tolerant group. The two ethanol-treated groups were impaired to the same extent when challenged on day 60. Partial generalization of this behavioural tolerance to ethanol was observed, as the behaviourally augmented tolerant group was less impaired than the physiologically tolerant group for a tail flick response to painful stimuli after an ethanol challenge on day 30. However, the two ethanol-treated groups exhibited similar impairments of locomotor activity after an ethanol challenge on day 40. No differences in muscarinic receptor binding among the control and two ethanol-treated groups were found. These findings demonstrate that behaviourally augmented tolerance to ethanol may be partially generalizable but is unrelated to changes in muscarinic cholinergic receptors.     

Effects of ethanol and toluene on fixed-ratio performance in short sleep and long sleep mice.

This study examined the effects of ethanol (EtOH) and toluene on fixed-ratio (FR) responding in mice selectively bred for sensitivity to the effects of EtOH on sleep time. Although the more sensitive long sleep (LS) mice showed greater EtOH-induced impairment in a motor performance task than did the less sensitive short sleep (SS) mice, changes in FR performance in the two lines did not differ in response to EtOH, regardless of route (oral or intraperitoneal) or time (40 vs. 60 min pre-session) of administration. These results emphasize the importance of considering task variables in determination of the behavior of different genotypes. In contrast to results with EtOH, the volatile inhalant toluene produced different effects on FR responding in the selected lines, with SS mice being more sensitive than LS mice.     

Naloxone nonselective suppression of drinking of ethanol,sucrose, saccharin,and water by rats

Naloxone, a nonselective opioid antagonist, has been demonstrated to reduce oral self-administration of ethanol (EtOH) in rats. Conflicting conclusions have been drawn about the effects of naloxone on consumption of non-EtOH control liquids. A preliminary meta-analysis found large and homogeneous effects of naloxone on EtOH consumption and heterogeneous effects on the consumption of control liquids. Although many of the authors concluded that their control liquid results were "not significant," when they were combined using meta-analytic techniques, it was apparent that there were some strong, but widely divergent, effect sizes. In the first experiment in the current study, 60 male Sprague-Dawley rats were trained to drink 10% EtOH in tap water over 3 weeks of limited-access sessions. Then, their limited-access consumption was measured in single-bottle tests of four liquids (water, 10% EtOH in water, an isocaloric sucrose solution, and an "equally sweet" saccharin solution) 15 min following an intraperitoneal injection of either saline or 1.0 mg/kg naloxone. Every animal was tested 36 times in a counterbalanced order: three times for each liquid following an injection of naloxone and six times for each liquid following an injection of saline. There were distinct differences in the quantity of each liquid consumed in the saline trials. However, the suppression percentages for each liquid in the naloxone trials were identical ( approximately 50%). There were significant correlations, in the range of.23-.42, between the mean amount of each liquid consumed during saline trials for each animal and the suppression percentage during naloxone trials for the same animal and liquid. When the animals were divided into high, low, and medium drinkers for each liquid, the low drinkers demonstrated a much lower suppression after naloxone treatment than did the other two groups. The data confirm that blockade of opioid receptors suppresses consumption of both EtOH and non-EtOH liquids to a degree that is related to the amount of voluntary, untreated consumption of the liquids.     

Effect of ethanol dose on amino acid and urea concentrations in the fed rat liver in vivo

In order to assess the role of ethanol oxidation in vivo on amino acid metabolism and urea synthesis, the changes in the concentrations of hepatic dicarboxylic amino acids, glutamine, alanine, carbamoylphosphate and urea were measured in fed rats at various times after the administration of 10 and 50 mmoles of ethanol/kg body wt, i.p. (1) The dose dependence of the acute effects of ethanol upon liver dicarboxylic amino acids in vivo has been demonstrated. The 10 mmoles/kg ethanol dose determines an accumulation by 30 per cent of aspartate and glutamate in the rat liver (30 and 60 min after ethanol injection) whereas the 50 mmoles/kg ethanol dose induces a 35 per cent fall in the aspartate level at the same time, and only a 20 per cent increase in glutamate concentration during the second hour following ethanol injection. (2) The dose-dependent effects of ethanol upon the hepatic level of urea are also shown. A significant decrease by 20 per cent in the liver content of urea is only observed 60 min after the administration of the 50 mmoles/kg ethanol dose. (3) On the contrary, the ethanol induced alterations in the hepatic alanine and glutamine concentrations are not dose-dependent. A 50 per cent decrease in alanine level and a rise (about 30 per cent) in glutamine concentration are observed 30 and 60 min after the administration of the two ethanol doses. The comparison between the effects of either 10 or 50 mmoles/kg ethanol doses leads to the conclusion that the rate of ethanol oxidation related to the malate-aspartate shuttle activity is directly connected with the glutamate (and aspartate) concentration. These findings suggest that ethanol reduces the hepatic urea concentration in vivo only when the ethanol dose injected to rats induces a rapid decrease in the aspartate/glutamate ratio (about 40 per cent within 15 min following the injection of the 50 mmoles/kg ethanol dose).     

Behavioral effects of taurine pretreatment in zebrafish acutely exposed to ethanol

Taurine (TAU) is an amino sulfonic acid that plays protective roles against neurochemical impairments induced by ethanol (EtOH). Mounting evidence shows the applicability of zebrafish for evaluating locomotor parameters and anxiety-like behavioral phenotypes after EtOH exposure in a large scale manner. In this study, we assess the effects of TAU pretreatment on the behavior of zebrafish in the open tank after acute 1% EtOH (v/v) exposure (20 and 60 min of duration) and on brain alcohol contents. The exposure for 20 min exerted significant anxiolytic effects, which were prevented by 42, 150, and 400 mg/L TAU. Conversely, the 60-min condition induced depressant/sedative effects, in which the changes on vertical activity were associated to modifications on the exploratory profile. Although all TAU concentrations kept locomotor parameters at basal levels, 150 mg/L TAU, did not prevent the impairment on vertical activity of EtOH[60]. Despite the higher brain EtOH content detected in the 60-min exposure, 42, 150, and 400 mg/L TAU attenuated the increase of alcohol content in EtOH[60] group. In conclusion, our data suggest that both protocols of acute EtOH exposure induce significant changes in the spatio-temporal behavior of zebrafish and that TAU may exert a preventive role by antagonizing the effects induced by EtOH possibly due to its neuromodulatory role and also by decreasing brain EtOH levels. The hormetic dose-response of TAU on vertical exploration suggests a complex interaction between TAU and EtOH in the central nervous system.     

Pressure reversal of the depressant effect of ethanol on spontaneous behavior in rats

This study deals with the interaction between high pressure and a sub-hypnotic dose of ethanol in rats. Male Sprague-Dawley rats were given either ethanol 1.5 g/kg or saline IP and subsequently exposed to 1 atmosphere absolute pressure (ATA) air or to 1, 12, 24 or 48 ATA of helium-oxygen (heliox). The gas temperature was adjusted to offset ethanol and helium-induced hypothermia. Ethanol induced a characteristic unsteady pattern of locomotion which was completely reversed at 48 ATA, partially reversed at 24 ATA, but not affected at 12 ATA. Other behavioral effects of ethanol such as depression of total motor activity and rearing were similarly affected. Blood and brain concentrations of ethanol in the pressure groups did not differ significantly from concentrations measured in the 1 ATA groups. A similar pattern of reversal was observed whether the compression was initiated 4, 10 or 16 min after injection. These results show that hyperbaric exposure antagonizes the depressant effect of ethanol on spontaneous behavior in rats. This antagonism does not appear to be due to changes in ethanol distribution or elimination.     

Monosialogangliosides (GM1 and AGF2) reduce acute ethanol intoxication: Sleep time mortality,and cerebral cortical Na+, K+-ATPase

Ganglioside pretreatment of mice reduced the sleep time, mortality, and loss of cerebral cortical membrane Na⁺, K⁺ -ATPase associated with acute ethanol treatment. Gangliosides GM1 and AGF2 (an internal ester of GM1) were optimally effective at a dose of 20 mg/kg when injected 24 hr and 1 hr prior to ethanol injection (3 mg/kg). Blood ethanol levels were slightly lower in GM1- and AGF2-pretreated mice than in the saline-ethanol group. The sleep times of GM1- and AGF2-injected mice were 32 ± 10 min and 34 ± 12 min respectively vs. 58 ± 15 min for saline-ethanol-treated animals. Mortality was 64% and 34% in animals pretreated with GM1 or AGF2 and ethanol, respectively, while in animals treated with saline and ethanol the mortality was 80%. No decrease in crotical membrane Na⁺, K⁺ -ATPase was seen at 15 min or 40 min after ethanol administration in animals pretreated with AGF2. The decrease in cortical membrane ATPase from GM1-treated animals was similar to losses in saline-ethanol-treated animals (25% after 15 min and 40% min). Pretreatment with either AG4 (asialo GM1) or sialic acid did not affect any of the parameteres tested.     

Evaluation of the effects of aluminium,ethanol and their combination on rat brain synaptosomal integral proteins in vitro and after 90-day oral exposure

The effects of aluminium lactate (Al-lactate) on the rat cerebral synaptosome integral proteins adenosinetriphosphatase (ATPase) and acetylcholinesterase (AChE) were studied in vitro and in vivo. Coexposure with ethanol (EtOH) was studied in both situations. Isolation of synaptosomes was carried out using isoosmotic Percoll gradients. In in vitro experiments, the synaptosomes were exposed to different concentrations of Al-lactate in the incubation mixture. Al-lactate caused decreases in total ATPase and AChE activities concentration dependently. The decrease in ATP activity started at 0.2 mM concentration, and concentration for the 50% decrease of the enzyme activity (EC₅₀ ) was 1.1 mM. The decrease in AChE activity started at 5–10 mM concentration, and the EC₅₀ value was 15.8 mM. Coexposure with ethanol (2 mM) increased the EC₅₀ values similarly in both cases. After 90-day oral exposure of rats to Al-lactate (91.8 mg/kg/day), the serum aluminium level was 0.9–1.3 M/l. Coexposure with EtOH (3.0 g/kg/day) did not significantly increase the blood Al (0.7–2.2 M/l). Aluminium exposure caused a decrease in the blood EtOH concentration (0.6 mM/l) compared with blood EtOH (12.3 mM/l) in the rats exposed to ethanol only. In the rats studied 2 weeks after the Al exposure, the activities of ATPase and AChE were significantly lower than in the rats studied immediately after the exposure. Correspondingly, a significant decrease in AChE activity was found in Al- and EtOH-exposed rats, but in the control rats there were no differences between the study groups. Immediately after the 90-day dosing, the exposed rats did not differ significantly from the control rats. Based on the in vitro results, the neural membrane integral proteins ATPase and AChE may be considered as targets for the effects of aluminium and ethanol. Ninety-day in vivo exposure of rats to aluminium caused decrease in ATPase and AChE activities, detectable 2 weeks after the exposure.     

Effects of ethanol on body temperature of rats at high ambient pressure

Separately, ethanol and high ambient pressure cause hypothermia in laboratory animals. However, ethanol and high pressure have mutually antagonistic effects on several biological functions and the present experiments investigate their combined action on body temperature. Rats given saline, 1.5 g/kg ethanol or 3.5 g/kg ethanol were exposed to 1 bar air at 25-26 degrees C, 1 bar helium-oxygen at 30-31 degrees C, or 48 bar helium-oxygen at 33.5-34.5 degrees C. Ambient, colonic and tail-skin temperatures were monitored for 60 min. There were no significant differences in mean ambient or tail-skin temperatures between groups belonging to the same ambient condition. Colonic temperatures under the 1 bar conditions were 1.5-2 degrees C lower in the 3.5 g/kg ethanol group than in the saline and 1.5 g/kg ethanol groups, while no significant differences were observed between the groups at 48 bar. Comparisons of the colonic temperatures at the end of the observation period, i.e., 60 min after administration of ethanol, demonstrated that their values at 48 bar were significantly lower than at 1 bar after saline, significantly higher after 3.5 g/kg ethanol and identical across conditions in the 1.5 g/kg groups. The results suggest that high ambient pressure may counteract rather than potentiate the hypothermic effect of ethanol.     

Plasticity of GABAA receptors after ethanol pre-exposure in cultured hippocampal neurons

Alcohol use causes many physiological changes in brain with behavioral sequelae. We previously observed (J Neurosci 27:12367-12377, 2007) plastic changes in hippocampal slice recordings paralleling behavioral changes in rats treated with a single intoxicating dose of ethanol (EtOH). Here, we were able to reproduce in primary cultured hippocampal neurons many of the effects of in vivo EtOH exposure on GABA(A) receptors (GABA(A)Rs). Cells grown 11 to 15 days in vitro demonstrated GABA(A)R δ subunit expression and sensitivity to enhancement by short-term exposure to EtOH (60 mM) of GABA(A)R-mediated tonic current (I(tonic)) using whole-cell patch-clamp techniques. EtOH gave virtually no enhancement of mIPSCs. Cells pre-exposed to EtOH (60 mM) for 30 min showed, 1 h after EtOH withdrawal, a 50% decrease in basal I(tonic) magnitude and tolerance to short-term EtOH enhancement of I(tonic), followed by reduced basal mIPSC area at 4 h. At 24 h, we saw considerable recovery in mIPSC area and significant potentiation by short-term EtOH; in addition, GABA(A)R currents exhibited reduced enhancement by benzodiazepines. These changes paralleled significant decreases in cell-surface expression of normally extrasynaptic δ and α4 GABA(A)R subunits as early as 20 min after EtOH exposure and reduced α5-containing GABA(A)Rs at 1 h, followed by a larger reduction of normally synaptic α1 subunit at 4 h, and then by increases in α4γ2-containing cell-surface receptors by 24 h. Measuring internalization of biotinylated GABA(A)Rs, we showed for the first time that the EtOH-induced loss of I(tonic) and cell-surface δ/α4 20 min after withdrawal results from increased receptor endocytosis rather than decreased exocytosis.