Alcohol withdrawal syndrome in rats: neural and behavioral correlates

Rats were chronically implanted with electrodes in the ventral hippocampus, amygdala and anterior cortex and maintained on liquid diets as their only source of calories and fluid for 15 days. The diet consisted of 35–40% of the calories in the form of ethanol while a control group was pair-fed identical diets with sucrose isocalorically substituted for ethanol. On the sixteenth day the diets were removed and electrographic activity and behavior were simulataneously observed for 8–10 hr. Withdrawal symptoms were observed beginning 2–4 hr following alcohol abstinence and included tail-stiffening, tremors, severe ataxia and auditory-induced convulsions. EEG epileptiform activity was observed and initially consisted of transient spike events, which usually became progressively organized into brief spike burst sor sustained paroxysmal activity. The results suggested that cortical bioelecric activity may not play a primary role in the genesis of behavioral hyperexcitability during alcohol withdrawal. The utility of the method of combined observations of neural bioelectric activity and behavior for the delineation of the neural substrates of alcohol withdrawal symptoms was discussed.     

Alcohol withdrawal reactions after chronic intake of chlordiazepoxide and ethanol

Withdrawal reactions were compared in C57BL/6J mice, which had been fed an ethanolic liquid diet containing chloridazepoxide (CDP, 3.2 or 6.4 mg/100 ml, group B or C, respectively) with those which had been administered an ethanol diet alone (group A) for 15 days. Group A showed a significantly more pronounced decrease in rectal temperature (4 to 10 hr) and a higher withdrawal score (4 to 14 hr) than mice in groups B and C. The differences in withdrawal signs still persisted even after mice were fed an ethanol diet without CDP for one extra day before withdrawal. The presence of metabolites of CDP in the blood during withdrawal could only account for a minor contribution to the protective effect. Our data are more suggestive of an increased rate of ethanol metabolism leading to lower blood alcohol levels during diet intake period as being the major factor. However, we cannot rule out the alternative possibility that CDP or its metabolites might interfere with the development of tolerance to and physical dependence on alcohol.     

Electroencephalographic and behavioral correlates in rats during repeated ethanol withdrawal syndromes

Rats chronically implanted with electrodes in the amygdala, thalamus, hippocampus, and cortex were addicted twice, separated by an interval of 2 weeks, with 18 days of ethanol liquid diet. The diet consumption and the blood ethanol levels (BELs) were carefully controlled twice a day during both addictive phases. After ethanol removal the behavioral and electroencephalographic (EEG) changes were continuously monitored for 24 h. During each withdrawal the behavioral and EEG changes appeared at the same time, the EEG changes being of shorter duration Behavioral and EEG changes (primarily in hippocampus) were more severe and of earlier onset during the second withdrawal. In spite of an ethanol liquid diet intake comparable to that of the first addiction, during the ethanol readdiction the BELs were found to fluctuate. The results support the hypothesis of an ethanol withdrawal potentiation through a mechanism of kindling of different brain areas related to the observed BEL fluctuations.     

河豚毒素对大鼠和小鼠纳洛酮催促吗啡戒断症状的影响

通过建立吗啡 (Mor)依赖大鼠及小鼠模型 ,观察河豚毒素 (TTX ,大鼠 0 .0 0 3～ 0 .1μg·kg- 1·d- 1,im ,5d ;小鼠 0 .0 2～ 0 .2 μg·kg- 1·d- 1,ip ,2d)对纳洛酮 (Nal)催促戒断症状的预防及治疗作用 .结果表明TTX抑制戒断后大鼠体重丢失 ;明显抑制Mor依赖小鼠Nal催促后的跳台反应 ,并促进催促后小鼠体重的恢复 .证实TTX可显著抑制Mor依赖大鼠和小鼠Nal激发的戒断反应 ,其效果与可乐定相近 .在防治戒断症状的有效剂量范围内 ,TTX不影响麻醉大鼠的血压 ,呼吸和心率 ,也不影响尼古丁诱发的神经反射活动 ,对痛觉反应和中枢神经系统无明显抑制作用 .     

Dissociation between physical dependence and volitional ethanol consumption: role of multiple withdrawal episodes

The experiment examined the effects of single and multiple episodes of forced administration of a liquid diet containing ethanol on subsequent volitional ethanol consumption. Rats were subjected to a series of 3 sequences of forced liquid diet consumption lasting 20, 50 and 50 days. One group (AD) received a liquid diet with 35–42% of the calories in the form of ethanol. Another group (SD) received identical diets except sucrose was isocalorically substituted for ethanol. Following each sequence a free-choice test was given in which the rats were allowed to choose between an alcohol diet, a sucrose diet and water. After 20 days of alcohol consumption, rats in the AD group rejected the alcohol diet, despite the occurrence of severe withdrawal symptoms including tail-stiffening, ataxia, tremors and hyperreactivity. During subsequent preference tests, a substantial, but transient, increase in alcohol self-selection was observed. It was concluded that rats may learn the association between alcohol and relief of withdrawal symptoms, but a number of withdrawal episodes are required.     

Zonisamide decreases ethanol intake in rats and mice

Several anticonvulsant agents, including topiramate and valproate, have been found to reduce alcohol consumption in rodent models of drinking. The question of whether the novel anticonvulsant agent, zonisamide, shares similar actions in either mice or rats was investigated in the present experiments. In an initial experiment, the consumption of a 10% ethanol-5% sucrose solution, available for one hour, by Wistar rats treated with lactose, topiramate, or zonisamide was determined. In a second experiment, the intake of a 10% ethanol/water solution, accessible for two hours, by C57BL/B6N mice treated with either zonisamide or vehicle was assessed. In the rat, 50 mg/kg (PO) doses of either topiramate or zonisamide produced significant, but moderate decreases in ethanol/sucrose intake. The administration of a 50 mg/kg (IP) dose of zonisamide to mice resulted in a marked lowering in ethanol consumption. These results provide evidence that zonisamide administration will decrease ethanol consumption by both mice and rats in limited access models of drinking, and might, like topiramate, be useful as a medication for alcoholism.     

Sound-induced seizures during ethanol withdrawal in mice

An ethanol withdrawal syndrome, consisting of tremors and convulsions, was induced in C57BL/6J mice by feeding them a liquid diet containing 27% of ethanol-derived calories at an environmental temperature of +12 to 13° C for 6 days. Control groups were pair-fed with liquid diets containing isocaloric amounts of sucrose or Laboratory Chow. Seven and 24 h after the beginning of withdrawal, all mice were exposed to bell ringing for 90 sec. This sound induced convulsions in nearly one-half of ethanol-consuming mice at 7 h and in a few mice at 25 h. Only one mouse of the control groups had a convulsion. These findings support the concept that the ethanol withdrawal syndrome is a partially latent state of hyperexcitability of the brain following depression by ethanol.     

Dopamine-sensitive adenylate cyclase in homogenates of rat striata during ethanol and barbiturate withdrawal

Summary Repeated administrations of ethanol and of phenobarbital to rats led to characteristic withdrawal symptoms when the drug had been stopped. Since both drugs affect brain dopamine metabolism, the postjunctional sensitivity to dopamine in the corpora striata was tested during ethanol or phenobarbital withdrawal. This was done by studying the dopamine-sensitive adenylate cyclase in homogenates of the corpora striata of ethanol- or phenobarbital-dependent rats. The results demonstrated a slight postjunctional subsensitivity to dopamine in withdrawal from both ethanol and phenobarbital. Both drugs, when added in vitro, did not affect the postjunctional sensitivity to dopamine. The results do not support the hypothesis, at least not in the case of dopamine, that a postjunctional supersensitivity to neurotransmitters is important for withdrawal symptoms after chronic administration of drugs inducing physical dependence.Part of the results were presented at the 17th Spring Meeting of the German Pharmacological Society, Mainz, March 23–26, 1976     

Failure of diphenylhydantoin to prevent alcohol withdrawal convulsions in mice

Alcohol withdrawal reactions were induced in mice using an established technique. Mice, administered 1.0 mmole/kg pyrazole daily were exposed for 3 days to 10 mg/l ethanol vapor and withdrawal was brought about by discontinuation of the exposure. Diphenylhydantoin administered in doses of 12, 20 or 50 mg/kg by either of two routes (i.p. or p.o.), failed to have any discernable effect on the withdrawal. A 100 mg/kg dose of diphenylhydantoin increased seizure scores. Chloral hydrate administration in doses of 175, 244 or 350 mg/kg, on the other hand, lowered seizure scores in a manner which was dose related and prompt. These findings suggest that the clinical use of diphenylhydantoin for control of the seizures seen in alcohol withdrawal should be re-evaluated. The seizure scores of mice not exposed to ethanol but administered 1.0 mmole/kg pyrazole daily for 3 days were negligible and well within values obtained with naive control mice not exposed to any pharmacological agent.     

Morphine withdrawal in mice selectively bred for differential sensitivity to ethanol

Mice which have been selectively bred for differences in sensitivity to acute doses of alcohol have also been shown to differ in severity of seizures upon withdrawal from chronic alcohol administration. We investigated the responsiveness of these mice to withdrawal from chronic morphine treatment. Mice were made dependent on morphine via pellet implantation, and withdrawal was precipitated with naloxone challenge. Mice which are less sensitive to the hypnotic effects of ethanol (short sleep: SS) displayed more jumping and wet dog shakes during withdrawal than did the more senstive long sleep (LS) mice. In addition, the amount of jumping was dependent on the dose of naloxone in both lines. Differences between lines in naloxone precipitated withdrawal may reflect differences in alterations in extrapyramidal dopaminergic activity, but other substrates for the observed differences cannot be discounted. Finally, the observed difference between SS and LS mice in severity of morphine withdrawal parallels the previously reported difference between these lines in seizure severity during withdrawal from alcohol.     

Dopaminergic involvement in withdrawal hypothermia and thermoregulatory behavior in morphine dependent rats

Thermoregulatory behavior was assessed in the rat by measuring the time taken to escape from a radiant heat source. The time to escape and the rise in core temperature accompanying exposure to heat were greater in morphine dependent (1 × 75 mg SC pellet implant for 72 hr) than in control rats. Injection of naloxone (1 mg/kg) into dependent rats produced a withdrawal hypothermia and decreased the time taken to escape from the heat source. Since rats undergoing withdrawal avoided heat at the same time that their core temperature was falling, the hypothermia is most likely due to a downward setting of the central thermostats rather than a direct activation of heat loss pathways. Both the withdrawal hypothermia and the behavioral changes were blocked by pimozide pretreatment (0.5 mg/kg) implicating a dopaminergic mechanism in the downward setting of the thermostats. Administration of naloxone 144 hr after pellet implantation produced similar effects to those in the 72 hr implanted group. Injection of morphine sulfate (4 mg/kg) 144 hr after implantation increased both the core temperature and the time taken to escape from heat suggesting that the effect of morphine in the dependent rat is to produce an upward setting of the thermostats.     

Electroencephalographic correlates of audiogenic seizures during ethanol withdrawal in mice

C57BL/6Bg mice had silver bead electrodes chronically implanted on the surface of the cortex and had their cortical EEG recorded during audiogenic seizures following ethanol withdrawal. For 7 days, the experimental groups were fed a liquid diet containing 6% v/v ethanol ad lib as the only source of food and water. The control group was fed a similar diet containing an isocaloric amount of sucrose. The cortical EEG's of experimental and control groups before, during, and after treatment were virtually identical. Only the experimental group was susceptible to audiogenic seizures. During audiogenic seizures, the cortical EEG showed no sign of spike waves or paroxysmal activity. This is in contrast to picrotoxin convulsions with these same mice as well as to spontaneous convulsions in animals following ethanol withdrawal. Similar EEG observations have been reported on audiogenic seizures from genetic and acoustically primed susceptibilities. Consequently, we suggest that all audiogenic seizure responses, including those during ethanol withdrawal, are a type of subcortical epilepsy.     

Induction of physical dependence upon ethanol in rats using intravenous infusion

Intravenous infusions were used to produce physical dependence upon ethanol in rats. The procedure proved to be safe, rapid, and reliable. Ethanol (30% v/v) was administered over a 7-day period. The mean daily dose ranged from 10–14 g/kg/day. Control rats were exposed to a comparable procedure except that saline, rather than ethanol, was infused. All ethanol treated rats that survived the intoxication period (n=11) showed signs of physical dependence (moderate to severe3 n=8; mild, n=3) following ethanol withdrawal. Saline treated rats (n=8) did not show any of these symptoms. The most reliable ethanol withdrawal signs observed were: spontaneous seizure (n=7), audiogenic seizure (n=7), tremors (n=6), tail stiffening (n=10) and body rigidity (n=9). These symptoms were analyzed in terms of their hour of onset and hour of maximum intensity following ethanol withdrawal. Application of the intravenous method for the study of ethanol self-administration is discussed.     

Barbiturate withdrawal and magnesium deficiency in mice

C57BL/6J male mice rendered physically dependent on phenobarbital exhibited significantly lower whole-brain and serum-magnesium concentrations than did control mice. The symptoms of phenobarbital withdrawal were remarkably similar to those seen in magnesium-deficient mice exposed to a low-magnesium diet without drug exposure. These findings suggest that brain magnesium deficits produced by chronic phenobarbital withdrawal could contribute to the observed phenobarbital withdrawal syndrome. Administration of MgSO₄ during withdrawal significantly reduced the incidence of tonic-clonic and lethal tonic seizures.     

Intramuscular/oral lorazepam in acute alcohol withdrawal and incipient delirium tremens

Summary

An open study was carried out in 21 chronic alcoholics with severe withdrawal symptoms and incipient delirium tremens to evaluate the efficacy of adjuvant treatment with intramuscular lorazepam (5?mg). All symptoms subsided within 2 hours after a single injection and remained under control with oral lorazepam (mean daily dose 7?mg). No adverse reactions attributable to lorazepam were observed.     

Alcohol withdrawal and magnesium deficiency in mice

DBA/2J mice exposed to chronic alcohol (ethanol) intoxication were found to have lower whole brain magnesium (Mg) concentrations than control animals. The symptoms of alcohol withdrawal were found to be strikingly similar to those seen in Mg deficient mice exposed to a low Mg diet without alcohol exposure. These findings suggest that CNS Mg deficits produced by alcohol exposure could contribute to the observed alcohol withdrawal syndrome. Serum Mg concentrations were also determined, and low correlations (less than or equal to 0.3) were found with brain Mg concentrations.     

Effect of dopamine agonists and antagonists on the lorazepam withdrawal syndrome in rats

1. The effects of dopaminergic agonists and antagonists were investigated on withdrawal signs in lorazepam-dependent rats. Physical dependence was developed by giving lorazepam admixed with food in the following dose schedules: 10 x 4, 20 x 4, 40 x 4, 80 x 4 and 120 x 7 mg/kg, daily for x days. 2. The parameters observed during the periods of administration of lorazepam and after its withdrawal were spontaneous locomotor activity (SLA), reaction time to pain, foot shock aggression (FSA) and audiogenic seizures. 3. During the withdrawal period, rats were divided into groups of 10 rats each. One group did not receive any drug and served as the control withdrawal groups. Three other groups received, separately, one of the following dopamimetic drugs: (i) 200 mg/kg per day, i.m., L-dihydroxyphenylalanine (DOPA; +50 mg/kg per day, i.m., carbidopa); (ii) 2 mg/kg per day, i.m., amphetamine; or (iii) 1 mg/kg per day, i.m., apomorphine. The remaining groups received one of the following dopamine antagonists: (i) 0.1 mg/kg per day, i.m., SCH 23390; (ii) 0.5 mg/kg per day, i.m., haloperidol; (iii) 0.5 mg/kg per day, i.m., centbutindol; and (iv) either 1 or 20 mg/kg per day, i.m., clozapine. 4. The withdrawal signs observed in the control group were hyperkinesia, hyperaggression and audiogenic seizures. 5. L-Dihydroxyphenylalanine (+ carbidopa), amphetamine and apomorphine potentiated hyperaggression and audiogenic seizures. The dopamine D2 receptor antagonists haloperidol, centbutindol and clozapine (at 20 mg/kg, i.m.) blocked all withdrawal signs. The D1 receptor antagonist SCH 23390 inhibited hyperkinesia and hyperaggression. The D4 receptor antagonist clozapine (at 1 mg/kg, i.m.) had no effect on any of the withdrawal signs. 6. It may be concluded that dopamine D2 receptors exert a dominant facilitatory influence, with partial contribution of D1 receptors, on the benzodiazepine withdrawal syndrome.     

Action of chlormethiazole in a model of ethanol withdrawal

Mice withdrawn from exposure for 14 days to ethanol inhalation showed the expected signs of ethanol withdrawal including convulsive behaviour. Injection of chlormethiazole (100 mg/kg) 5 h after the start of withdrawal, at the time that the convulsive behaviour was near maximal, resulted in the virtual disappearance of the withdrawal — induced behaviour within 30 min, with its reappearance by 60 min. A dose of chlormethiazole of 40 mg/kg was without effect. The time course of the effect of chlormethiazole (100 mg/kg) in the withdrawal test was similar to its effect in raising seizure threshold and decreasing locomotor activity. Chlormethiazole did not alter in vitro binding of [³H]-PN 200-110 to the dihydropyridine sensitive Ca²⁺ channel. Chlormethiazole, a drug used clinically to treat ethanol withdrawal, has therefore been shown to be effective in this animal model of withdrawal. Dihydropyridine calcium antagonists are also active in the model but chlormethiazole is likely to work by a different mechanism and it is suggested that this may be by increasing GABAergic function.     

Endorphin levels in human cerebrospinal fluid during alcohol intoxication and withdrawal

Levels of endorphins were determined in CSF from alcoholics while intoxicated or after 1 day, 1 week, and 3 weeks of abstinence, respectively, and from healthy volunteers. The level of endorphins was determined by a radioreceptor assay and two fractions were analyzed. With fraction 1, there were no significant differences between the groups, but the level was negatively correlated with the blood-alcohol level. The mean level of endorphin fraction 2 during the early withdrawal phase was significantly lower than those of the other groups. With respect to clinical conditions and monoamine metabolites, fraction 2 in early withdrawal correlated significantly to duration of abuse and age. During late withdrawal, fraction 1 level correlated to depressive symptoms and, after 3 weeks of abstinence, fraction 2 correlated to MOPEG levels. This study suggests that endorphin systems are affected during alcohol intoxication and withdrawal in alcoholics.     

Nimodipine in human alcohol withdrawal syndrome — an open study

The aim of this study was to evaluate the efficacy and tolerability of the DHP Ca2+ antagonist nimodipine in human AWS and post-AWS. Ten hospitalized alcoholics of both sexes with a diagnosis of AWS according to the DSM-III criteria were treated for 3 weeks in monotherapy with nimodipine p.o. at flexible daily dosages. Evaluation of AWS symptoms was performed at baseline and after 3, 5, 7, 10, 14 and 21 days. A statistically significant improvement of AWS was seen at evaluation on day 3, particularly in neurovegetative and psychopathological symptoms, and lasted up to the end of the study. The treatment was well tolerated and no side effects were observed or reported. In this pilot, open study nimodipine proved effective in the treatment of mild-to-moderate AWS. If these data are confirmed in a double-blind study nimodipine could be a rational alternative to benzodiazepines in the treatment of AWS.