Ethanol Physical Dependence Research Articles

Effect of Aripiprazole on Anxiety Associated With Ethanol Physical Dependence and on Ethanol-Induced Place Preference

In the present study, we investigated the effect of aripiprazole, a dopamine system stabilizer, on ethanol-induced psychological and physiological dependence and anxiety-like behavior. First we determined the effect of aripiprazole, a dopamine system stabilizer, on the development and expression of ethanol-induced place preference. Both the development and expression of ethanol-induced place preference was significantly suppressed by treatment of aripiprazole. Next, the withdrawal score gradually increased with increasing duration after the withdrawal from ethanol for 6 days in vehicle-treated mice and the maximal score was observed 10 h after the ethanol withdrawal. Aripiprazole caused no changes in the withdrawal score as compared to vehicle-treated mice. Under these conditions we investigated the effect of aripiprazole on the anxiety-like behavior of ethanol physical dependent mice, which were animals subjected to ethanol vapor for 6 days. The significant decrease of time spent in the open arms and number of open arm entries characterize the anxiety-like behavior in ethanol physical dependent mice, compared to control mice. These decreases were reversed by treatment of aripiprazole, which were inhibited by WAY100635, a serotonin 5-HT1A receptor antagonist. The present findings suggest that aripiprazole was efficient for reversing ethanol-induced place preference and anxiety-like behavior.

Enhancement of histone acetylation in midbrain of mice with ethanol physical dependence and its withdrawal

Enhancement of histone acetylation in midbrain of mice with ethanol physical dependence and its withdrawal

Age and strain differences in the rat of development of functional tolerance to ethanol by mice.

Abstract The time course of development of functional tolerance to ethanol was investigated in mice during the inhalation of ethanol vapour, using loss of righting reflex as the behavioural end-point. In male mice of the TO Swiss strain, weanling mice (18 days) showed no development of tolerance during continuous or repeated exposure to ethanol vapour for 6 h. Adolescent TO Swiss mice (35–40 days) showed rapid development of functional tolerance, reaching a state where 2x the original effective concentration of ethanol in blood was required to produce loss of righting reflex within 5 h. Older adult mice (150–200 days) showed some development of tolerance during continuous or repeated exposure to ethanol for 5 h but this was much less than that seen in adolescent mice. When adolescent males of the C57BL, TO Swiss and DBA2 strains were compared, marked differences were observed. C57BL mice showed very rapid development of functional tolerance to ethanol in which more than 2 × the original effective dose was required to produce loss of righting reflex after about 3 h of ethanol exposure. TO Swiss mice showed somewhat slower development of ethanol tolerance. DBA2 mice showed little evidence of development of functional tolerance over the time course of these experiments. Evidence was also obtained that similar age and strain differences may exist with respect to tolerance to the hypothermic effects of ethanol. These results are discussed in relation to current concepts of ethanol sensitivity, tolerance and physical dependence.

Expression of Serotonin Transporter in Mice With Ethanol Physical Dependency

In the present study, we investigated whether ethanol physical dependence causes changes of serotonin transporter (SERT) expression in the brain. SERT expression increased in the cingulate cortex, nucleus accumbens, hippocampal CA1-CA3 layers, and mediodorsal nucleus of the thalamus and decreased in the basolateral nucleus of the amygdala. In addition, chronic ethanol treatment increased SERT mRNA in the dorsal raphe nucleus from which serotonergic neurons originate, although no SERT mRNA was detected in the regions where SERT protein increased. These findings suggest that alteration of SERT levels in the brain may be related to emotional changes observed in ethanol physical dependence.

Increase in Expression of α1 and α2/δ1 Subunits of L-Type High Voltage-Gated Calcium Channels After Sustained Ethanol Exposure in Cerebral Cortical Neurons

Previous reports revealed up-regulation of L-type high voltage-gated calcium channels (HVCCs) in mouse brains with ethanol physical dependence. We investigated mechanisms of enhancement of L-type HVCC function using mouse cerebrocortical neurons exposed to 50 mM ethanol for 3 days and the brains of mouse physically dependent on ethanol. Ethanol facilitated 30 mM KCl-stimulated 45Ca2+ influx in dose- and duration-dependent manners, which was abolished by nifedipine, an inhibitor specific to L-type HVCCs, but not by inhibitors for other types of HVCCs. Increase in [3H]PN200-110 binding to the particulate fractions from the ethanol-treated neurons was due to increased Bmax value with no changes in Kd value. Western blot analysis showed the increased expression of α1C, α1D, and α2/δ1 subunits with decreased β4 subunit expression and no changes in expressions of α1A, α1B, α1F, and α2 subunits. A similar pattern of the changes in the expression of these subunits of L-type HVCCs were observed in the cerebral cortex from mouse with ethanol physical dependence. These results indicate that sustained ethanol exposure to the neurons induces up-regulation of L-type HVCCs, which is due to increased expressions of α1C, α1D, and α2/δ1 subunits, and produces no alterations in P/Q- and N-type HVCC functions.

Ethanol physical dependence is accompanied by up-regulated expression of L-type high voltage-gated calcium channel α1 subunits in mouse brain

We investigated how functional changes in high voltage-gated calcium channels (HVCCs) occurred in the cerebral cortex of mouse with ethanol physical dependence. The continuous treatment of mice with ethanol vapor for 8 days significantly increased the expressions of α1C, α1D, and α2/δ1 subunits of L-type HVCCs in association with decreased level of β4 subunit of L-type HVCCs, although α1A and α1B subunits of P/Q- and N-type HVCCs, respectively, showed no alterations. [ 3H]Diltiazem binding to the particulate fractions increased with increased B max value and no changes of K d value. These results indicate that ethanol physical dependence accompanies the up-regulation of L- type HVCCs, which is due to increased expression of α1C, α1D, and α2/δ1 subunits.

CHARACTERISTICS OF CATECHOLAMINE RELEASE FROM ADRENAL CHROMAFFIN CELLS CULTURED IN MEDIUM CONTAINING ETHANOL—I. SPONTANEOUS AND K <sup>+</sup> -INDUCED RELEASE

Bovine adrenal chromaffin cells were dissociated and grown in primary culture for 9 days. Three days after plating, half the cultures were grown in a medium containing 200 mM ethanol and the other half in a control medium, for a further 6 days. The catecholamine content of the ethanol-treated cells was increased after 6 days of ethanol treatment, compared to control cells and there was a slight reduction in protein and DNA content. An enhanced spontaneous release of catecholamines was seen, which was Ca(2+)-dependent and was inhibited by cadmium but not by the organic dihydropyridine Ca2+ antagonist nitrendipine. The fraction of catecholamines released by K+ was also enhanced in ethanol-treated preparations, particularly at high K+ or Ca2+ concentrations. Release induced by K+ was sensitive to inhibition by both cadmium and organic dihydropyridine Ca2+ antagonists. The results show many similarities with changes observed in catecholaminergic transmission in rat brain during the development of ethanol physical dependence.

Ethanol and barbiturate withdrawal convulsions are extensively codetermined in mice

Selective breeding was used to produce lines of mice which differ markedly from one another in ethanol physical dependence development as indexed by handling-induced convulsions (HIC) induced by withdrawal from ethanol. These are known as the Withdrawal Seizure Prone (WSP) and Withdrawal Seizure Resistant (WSR) selected lines. Mice selectively-bred for severe HIC (Withdrawal Seizure Prone lines) exhibited 3-fold greater HIC scores than did mice selectively-bred for mild HIC (Withdrawal Seizure Resistant lines) after five generations of selective-breeding. When phenobarbital was used as the dependence-producing drug rather than ethanol, the WSP vs. WSR differences in HIC were similar to those seen with ethanol. This implies that a high degree of commonality exists between ethanol and phenobarbital in the determinants of this commonly used index of physical dependence. Both WSP and WSR mice showed equivalent brain phenobarbital concentrations and equal functional tolerance development as indexed by several measures of impairment.

Ethanol and nitrous oxide produce withdrawal-induced convulsions by similar mechanisms in mice

Twenty generations of selective breeding were used to produce lines (strains) of mice which differ markedly from one another in ethanol physical dependence development as indexed by handling-induced convulsions (HIC) induced by withdrawal from ethanol. These withdrawal seizure prone (WSP) and withdrawal seizure resistant (WSR) selection lines now differ by over 10-fold in HIC scores after equivalent exposure to intoxicating levels of ethanol via inhalation. Since handling-induced convulsions can be readily elicited following withdrawal from nitrous oxide, we sought to determine if the very large differences in ethanol withdrawal-induced HIC bred into these selection lines would generalize to nitrous oxide. Following a 60 min exposure to 75% nitrous oxide (in O 2), a greater than 10-fold difference in HIC nitrous oxide 2-fold difference in tremor incidence was seen upon withdrawal in WSP vs. WSR mice. These findings closely parallel those seen with ethanol, and demonstrate that a large degree of commonality exists in the genes and the mechanisms determining these withdrawal signs. HIC elicited by nitrous oxide withdrawal were readily suppressed by ethanol, and HIC elicited by ethanol withdrawal were promptly suppressed by 75% nitrous oxide in WSP mice. Nitrous oxide also suppressed HIC and tremor associated with nitrous oxide withdrawal.

Dihydropyridine‐Sensitive Ca2+ Channels and Inositol Phospholipid Metabolism in Ethanol Physical Dependencea

Dihydropyridine‐Sensitive Ca²⁺ Channels and Inositol Phospholipid Metabolism in Ethanol Physical Dependence^a

Increased dihydropyridine-sensitive calcium channels in rat brain may underlie ethanol physical dependence

Ethanol physical dependence can be viewed as a state of latent hyperexcitability in brain which is exposed on withdrawal of the drug. This hyperexcitability may reflect an increased sensitivity to Ca 2+ of central neurones. Dihydropyridine (DHP) binding sites which represent a subtype of neuronal Ca 2+-channel, are increased in brains from ethanol-dependent rats as are functional effects of the DHP Ca 2+-channel activator, BAYK8644. These effects are reversed by DHP Ca 2+ inhibitors, which also prevent the ethanol physical withdrawal syndrome. These results suggest that an increase in DHP-sensitive Ca 2+-channels on central neurons may represent the molecular basis for ethanol physical dependence.

Specific ethanol withdrawal seizures in genetically selected mice

We are selectively breeding mice prone (WSP) and resistant (WSR) to ethanol withdrawal seizures assessed by handling induced convulsions (HIC). The possibility that differences between the lines in HIC scores are a result of differences in general CNS excitability not specific to ethanol withdrawal was examined. Using treatments which produce generalized seizures (electroconvulsive shock, strychnine, and flurothyl) and gamma amino-butyric acid (GABA) antagonists (picrotoxin, bicuculline, and pentylentetrazol), the ED 50 for seizures was determined in the selected lines. In addition, the sensitivity of WSP and WSR mice to the anticonvulsant actions of ethanol against each treatment was determined. Neither the convulsant amperage 50 (CA 50) for ECS nor the ED 50 for any drug treatment differed for the selected lines. When ethanol (1.5 g/kg) was administered prior to ECS, there was a dramatic differential suppression of ECS in the lines: the CA 50) of WSR mice was elevated 5-fold, whereas the CA 50 of WSP mice increased only two fold. Ethanol pretreatment also elevated the ED 50 for strychnine and flurothyl in WSR mice significantly more than WSP mice, but the line difference was smaller than for the anticonvulsant effect against ECS. The ED 50s for the GABA antagonists were not different between the WSR and WSP lines after ethanol pretreatment. We conclude that genetic selection is producing lines of mice that differ specifically in the degree of seizure severity caused by withdrawal from ethanol physical dependence and not in generalized CNS excitability. An increased sensitivity to the anticonvulsant effects of ethanol against some convulsant treatments has appeared as a correlated response to selection in the WSR line.

Genetic correlations with ethanol withdrawal severity

A major goal of pharmacogenetic research on alcoholism remains the identification of some “marker” that could predict the liability of a particular individual for a genetic susceptibility to develop alcoholism. The present paper presents evidence that the severity of withdrawal from physical dependence on ethanol varies widely among inbred strains of mice, and that withdrawal severity is negatively genetically correlated with initial sensitivity and magnitude of tolerance to ethanol hypothermia. These correlations are supported by differences in hypothermic response between replicate lines of mice genetically selected for susceptibility and resistance to ethanol withdrawal seizures. The genetic relationships reported suggest that the effects of ethanol on thermoregulation in mice may offer a predictive marker for susceptibility to ethanol physical dependence.

Ethanol elimination rates in normal and ethanol dependent animals

Ethanol elimination rates were determined in rats using an intravenous route of ethanol administration after several experimental manipulations. Twenty-four hr food deprivation resulted in a 30% reduction to 35 mg/100ml blood/hr in elimination rate from a non-deprived rate of 50 mg/100 ml blood/hr. After 2 months of ethanol drinking (5% v/v), 24 hr starvation resulted in only a 10% reduction in elimination rate (45 mg/100 ml blood/hr), and did not increase the non-food-deprived rate (49.2 mg/100 ml blood/hr) over that obtained in the above animals' drinking water rather than 5% ethanol. Animals which chronically overdrank ethanol or water for 3 months on a schedule-induced polydipsia procedure, known to result in ethanol physical dependence, showed a decreased rate of ethanol elimination (37.9 mg/100 ml blood/hr for ethanol drinkers; 35.0 mg/100 ml blood/hr for water drinkers) in the non-food deprived condition. By providing 750 mg of liver powder daily as a food supplement in the ethanol overdrinking regimen, the ethanol elimination rate remained at a rate comparable to the normal animal (48.4 mg/100 ml blood/hr).