Effects of repeated administration of chlordiazepoxide on spontaneous locomotor activity in mice

Spontaneous locomotor activity has been studied in mice treated with single or repeated doses (five daily injections) of chlordiazepoxide. The repeated administration enhanced the stimulatory action of the lower doses of the drug, while the depressant effect of the higher doses was reduced.     

Context-dependent sensitization to ethanol in zebrafish (Danio rerio)

One of the most robust and readily measurable effects of moderate doses of ethanol on zebrafish behavior is locomotor hyperactivity. Two experiments were designed to examine the effects of repeated exposures to ethanol on ethanol-induced locomotor hyperactivity, and to determine whether these effects are context-dependent. Adult, wild-type zebrafish were given repeated exposure to ethanol in the presence of one contextual stimulus (A), while exposed to water in the presence of a second contextual stimulus (B). Exposure to ethanol consistently induced locomotor hyperactivity. After repeated exposures, animals tested with ethanol in the ethanol-paired context (A) showed sensitization of locomotor activity. When tested with ethanol in the unpaired context (B), however, sensitization was not observed. When tested in the absence of ethanol, there were no differences in responding to the paired and unpaired stimuli. This is the first demonstration of ethanol-induced locomotor sensitization in zebrafish. Moreover, this sensitization was context-specific, indicating that learning can modify drug-induced behaviors in zebrafish.     

Effect of the combined administration of ethanol and acamprosate on rabbit EEG

Central effect of ethyl alcohol and acamprosate is based on similar mechanisms. It is mainly connected with their effect on GABAergic, glutamatergic, serotonergic and opioid transmission. Thus, the question arises whether acamprosate administered together with alcohol increases acute central effects of ethanol. We have studied the effect of joint administration of acamprosate with ethanol in rabbits on EEG results from: frontal cortex, hippocampus and midbrain reticular formation. Acamprosate was applied into the stomach at a single dose of 400 mg kg(-1) or repeated doses of 200 mg kg(-1)/day (for 14 days). Ethanol at the dose of 0.8 g kg(-1) was administered iv 120 min after a single dose of acamprosate, or 4 h after the last dose of the drug. Ethanol caused an increase in the slow frequencies (0.5-4 Hz) in the recording, as well as a marked decrease in the fastest frequencies (13-30 and 30-45 Hz). Acamprosate administered jointly with ethanol increased the effect of ethanol on EEG recording; the amount of the fastest frequencies was decreased. When administered as repeated doses, it enhanced alcohol-related changes in EEG, both within slow and fast frequencies. Consumption of ethanol during acamprosate treatment may lead to intensification of central effects of ethanol.     

Influence of clonazepam and carbamazepine on alcohol withdrawal syndrome, preference and development of tolerance to ethanol in rats.

The effects of clonazepam (0.3 and 1.0 mg/kg or 0.1 mg/kg, b.i.d., 5 days) and carbamazepine (50 and 100 mg/kg or 12.5 and 50 mg/kg b.i.d., 5 days) on alcohol withdrawal syndrome in rats were investigated. Moreover, the influence of clonazepam (0.3 mg/kg, single dose, or repeated doses for 8 days) and carbamazepine (50 mg/kg, single dose, or repeated doses for 8 days) on the development of tolerance to ethanol was also examined. To study the influence of clonazepam and carbamazepine on preference to ethanol, both drugs were administered for 5 days during the last week of the experiment, (clonazepam at 0.1 mg/kg, b.i.d., i.p. and carbamazepine at 12.5 mg/kg, b.i.d, i.p.). Clonazepam and carbamazepine administered at single doses as well as multiple doses diminished the symptoms of withdrawal syndrome. Clonazepam did not prevent the development of tolerance to sleep-inducing and hypothermal action of ethanol, while carbamazepine prevented the development of tolerance to hypnotic effect of ethanol. Carbamazepine clearly reduced preference to ethanol (significantly vs. the control group and vs. the baseline values). Clonazepam also diminished preference to alcohol, but only in comparison with baseline values.     

Influence of captopril and enalapril on some central effects of ethanol

The influence of captopril and enalapril on acute toxicity of ethanol, ethanol-induced hypothermia, ethanol sleeping time has been investigated in mice. Moreover, the combined effect of captopril and enalapril on spontaneous locomotor activity in mice has been examined. The captopril (5 and 20 mg/kg) and enalapril (5 and 20 mg/kg) were injected intraperitoneally i.p. The drugs were given as single or repeated doses for 10 days. It has been shown that the captopril and enalapril administered in single doses decreases, but chronic administration increases acute toxicity of ethanol. Captopril and enalapril in single doses enhanced, but chronic administration inhibits hypothermic effect of ethanol. Captopril and enalapril reduces ethanol sleeping time. Captopril and enalapril administered for 10 days and enalapril in a single dose 20 mg/kg decreases ethanol induced hyperactivity.     

Effect of ethanol on fatal carbon monoxide poisoning in awake rats

The effect of ethanol on fatal carbon monoxide (CO) poisoning was investigated in mice injected intraperitoneally with ethanol. Ethanol (1.5 and 3.0 g/kg) was injected 15 min prior to exposure to gas containing 6.6% CO. The survival period was significantly lengthened with ethanol in proportion to the doses injected, although the carboxyhemoglobin (CO-Hb) saturation level in postmortem blood was almost the same in all groups. On the other hand, the CO-Hb level in the blood of mice injected with ethanol was significantly lower than that of control mice during the early exposure period when all mice were still alive.

Our results showed that the acute ethanol injection did not influence the CO-Hb saturation level in blood at death, but did affect the duration of survival, probably because of ethanol's ability to decrease blood flow and CO intake.     

Effects of frontal polar cortical ablation and cycloheximide on ethanol tolerance in rats.

Thirty adult male Wister rats were pretrained to criterion on the moving belt test, and then made tolerant to ethanol by daily administration of increasing doses over a period of 3 weeks. After a one-month recovery period, they were divided into 3 groups, subjected to bilateral frontal polar cortical ablations, sham-operation and no operation respectively. After postoperative recovery, the cycle of ethanol treatment and testing was repeated. Only the lesioned group failed to reacquire tolerance. A pilot experiment showed that occipital cortical ablations also prevented tolerance. In a second experiment 32 rats, which had similarly undergone and then recovered from an initial period of ethanol tolerance, were divided into 4 groups which received daily treatment with sucrose plus cycloheximide (0.3 mg/kg), sucrose plus saline, ethanol plus cycloheximide, and ethanol plus saline respectively. Only the ethanol plus saline group re-acquired tolerance. Tt is concluded that frontal polar cortical lesions and cycloheximide can both block the development of tolerance to ethanol in animals previously shown to be capable of developing such tolerance.     

Effect of carbon monoxide inhalation exposure in mice on drug metabolism in vivo

Experiments were undertaken to evaluate the action of carbon monoxide (CO) on the mixed-function oxidase (MFO) system in vivo. Mice were exposed to 500 ppm CO for 8 h per day in an inhalation chamber under dynamic airflow conditions. Hexobarbital (150 mg/kg, i.p.), zoxazolamine (150 mg/kg, i.p.) or ethanol (2 mg/g, i.p.) was given to each group of mice during CO exposure and disappearance of the drug from blood or brain was determined while CO exposure continued. The experiments were repeated with different groups of animals which were exposed to CO for 3 or 5 days. Hexobarbital and ethanol metabolism were not affected by CO following either one day exposure or repeated exposure. There was no statistically significant difference in the brain level of zoxazolamine in animals exposed to CO when compared to control. These studies indicate that in vivo metabolism of hexobarbital, zoxazolamine and ethanol in mice is not affected by exposure to 500 ppm CO under the conditions employed in the present study.     

Locomotor stimulant effects of intraventricular injections of low doses of ethanol in rats: acute and repeated administration

Rationale Low doses of ethanol stimulate locomotion in mice, but in rats the typical response to peripheral ethanol administration is a dose-dependent suppression of locomotion. Moreover, chronic ethanol administration fails to produce signs of locomotor sensitization in rats.Objective The present study was undertaken to determine whether intraventricular (i.c.v.) infusions of low doses of ethanol (as determined by comparisons with systemic doses, and by analyses of brain extract ethanol levels) could increase locomotor activity in rats after acute or repeated administration.Methods Male rats received acute doses of ethanol i.p. (0.0, 0.25, 0.5, 1.0, or 2.0 g/kg) or i.c.v. (0.0, 0.7, 1.4, or 2.8 mol) and were tested for motor activity. In a third experiment, repeated i.c.v. vehicle or ethanol (2.8 mol) was administered for 15 sessions over a 30-day period, and motor activity was recorded. This phase was followed by a single challenge session, in which a low dose of ethanol (0.7 mol) was injected i.c.v. to both groups of rats.Results Rats injected with i.p. ethanol showed no increase in activity at low doses, with higher doses suppressing activity. In contrast, i.c.v. injections of low doses of ethanol increased motor activity. After repeated administration, ethanol-treated rats were more sensitive than control-treated rats to the locomotor stimulant effect of ethanol.Conclusions These results demonstrate that central administration of low doses of ethanol can increase locomotor activity in rats and suggest that i.c.v. ethanol can produce some signs of motor sensitization, a characteristic that has been related to the potential addictive properties of many drugs.     

Effects of high dose transdermal nicotine replacement in cigarette smokers

RATIONALE: Nicotine replacement therapies (NRT) have been evaluated to facilitate cigarette smoking reduction in smokers unwilling or unable to quit. In most of these studies, only conventional doses of NRT have been tested and higher doses may be required to result in significant reductions in smoking and in biomarkers of exposure. OBJECTIVE: To determine if higher NRT doses in conjunction with smoking are safe and may promote significant reductions in cigarette smoking and biomarkers of exposure. METHODS: A dose-ranging, within-subject design was implemented to evaluate the effects of 15, 30 and 45 mg nicotine-patch treatment on measures of safety and the extent of smoking reduction and biomarker exposure per cigarette in smokers (N=20 completers) not immediately interested in quitting. RESULTS: Concurrent smoking and NRT were generally tolerated and resulted in no changes in blood pressure or heart rate. Slightly less than 10% of the study sample was not given the highest dose of NRT due to side effects. Self-reported cigarette smoking decreased with increasing doses of nicotine replacement and significant reductions were observed for total NNAL (a carcinogen biomarker) and carbon monoxide. However, even at the 45 mg dose, increased carbon monoxide and total NNAL per cigarette occurred, even though cotinine levels increased on average, 69.3% from baseline. CONCLUSIONS: The present results suggest that the use of high dose NRT is safe, leads to significant reductions in smoking (-49%), significant but less reductions in total NNAL (-24%) and carbon monoxide (-37%) due to compensatory smoking.     

Significance of acetaldehyde in ethanol-induced effects on catecholamine metabolism and motor activity in the mouse

The effect of acetaldehyde (0.7 g/kg, orally) or 4-methylpyrazole (8 mg/kg i.p.) and ethanol (7 g/kg orally) on the net accumulation of ³H-catecholamines (³H-CA) formed from ³H-tyrosine in the mouse brain was studied. Both drug regimens increased the yield of ³H-CA, similar to previous findings with ethanol alone. The effect of acetaldehyde was prevented by pretreatment with nialamide (100 mg/kg i.p.), a monoamine oxidase inhibitor. The ethanol-induced increase in ³H-CA accumulation was, if anything, enhanced by pretreatment with 4-methylpyrazole, which inhibits alcohol dehydrogenase. Acetaldehyde (100 mg/kg i.v.) and possibly, to some extent, ethanol (2 g/kg i.v.) released ¹⁴C-octopamine formed from ¹⁴C-tyramine in the mouse heart, whereas neither of the drugs (in the same doses) seemed to release reserpine-resistant ³H-noradrenaline from the mouse heart, an effect obtained by d-amphetamine (0.2 mg/kg i.v.). Pretreatment with 4-methylpyrazole (8 mg/kg i.p.) potentiated the stimulant action of ethanol (2 g/kg i.p.) on motor activity in the mouse. It is concluded that: 1. Acetaldehyde is not necessary to obtain the effects of ethanol on ³H-CA-accumulation and motor activity in the mouse. 2. The slight CA-releasing effect of ethanol and acetaldehyde is different from that of low doses of amphetamine and may possibly imply release of amines from the storage granules.     

Toxicity of Fire Smoke

This review is an attempt to present and describe the major immediate toxic threats in fire situations. These are carbon monoxide, a multitude of irritating organic chemicals in the smoke, oxygen depletion, and heat. During the past 50 years, synthetic polymers have been introduced in buildings in very large quantities. Many contain nitrogen or halogens, resulting in the release of hydrogen cyanide and inorganic acids in fire smoke as additional toxic threats. An analysis of toxicological findings in fire and nonfire deaths and the results of animal exposures to smoke from a variety of burning materials indicate that carbon monoxide is still likely to be the major toxicant in modern fires. However, the additional toxic threats mentioned above can sometimes be the principal cause of death or their addition can result in much lower than expected carboxyhemoglobin levels in fire victims. This analysis also revealed that hydrogen cyanide is likely to be present in appreciable amounts in the blood of fire victims in modern fires. The mechanisms of action of acute carbon monoxide and hydrogen cyanide poisonings are reviewed, with cases presented to illustrate how each chemical can be a major contributor or how they may interact. Also, lethal levels of carboxyhemoglobin and cyanide in blood are suggested from an analysis of the results of a large number of fire victims from different fire scenarios. The contribution of oxygen depletion and heat stress are more difficult to establish. From the analysis of several fire scenarios, they may play a major role in the room of origin at the beginning of a fire. The results in animal studies indicate that when major oxygen depletion (<10%) is added to lethal or sublethal levels of carbon monoxide or hydrogen cyanide its major role is to substantially reduce the time to death. In these experiments the carboxyhemoglobin level at death was slightly reduced from the expected level with exposure to carbon monoxide alone. However, blood cyanide was reduced by a factor of ten from the expected level with exposure to hydrogen cyanide alone. This is another factor (among many other presented) complicating the task of establishing the contribution of cyanide in the death of fire victims, from its analysis in their blood. Finally the role of ethanol intoxication, as it may influence carboxyhemoglobin levels at death, is reviewed. Its role is minor, if any, but the data available on ethanol in brain tissue and blood of fire victims confirmed that brain ethanol level is an excellent predictor of blood ethanol.     

Differing effects of short-chain alcohols on body temperature and coordinated muscular activity in mice

Administration of single doses of ethanol, 1-propanol, 1-butanol or 1-pentanol to mice caused hypothermia and impairment of rotarod performance. Repetitive doses, at 24-72 hr intervals led to development of tolerance to the hypothermic effects of ethanol but not of the other alcohols. No tolerance was seen in the impairment of rotarod performance with repeated doses of any of the alcohols. Ethanol did show an intersession tolerance on rotarod performance; at 20 and 80 min after injection, blood levels were similar, while performance was impaired at 20 but not at 80 min.     

Toxicity of fire smoke

This review is an attempt to present and describe the major immediate toxic threats in fire situations. These are carbon monoxide, a multitude of irritating organic chemicals in the smoke, oxygen depletion, and heat. During the past 50 years, synthetic polymers have been introduced in buildings in very large quantities. Many contain nitrogen or halogens, resulting in the release of hydrogen cyanide and inorganic acids in fire smoke as additional toxic threats. An analysis of toxicological findings in fire and nonfire deaths and the results of animal exposures to smoke from a variety of burning materials indicate that carbon monoxide is still likely to be the major toxicant in modern fires. However, the additional toxic threats mentioned above can sometimes be the principal cause of death or their addition can result in much lower than expected carboxyhemoglobin levels in fire victims. This analysis also revealed that hydrogen cyanide is likely to be present in appreciable amounts in the blood of fire victims in modern fires. The mechanisms of action of acute carbon monoxide and hydrogen cyanide poisonings are reviewed, with cases presented to illustrate how each chemical can be a major contributor or how they may interact. Also, lethal levels of carboxyhemoglobin and cyanide in blood are suggested from an analysis of the results of a large number of fire victims from different fire scenarios. The contribution of oxygen depletion and heat stress are more difficult to establish. From the analysis of several fire scenarios, they may play a major role in the room of origin at the beginning of a fire. The results in animal studies indicate that when major oxygen depletion (<10%) is added to lethal or sublethal levels of carbon monoxide or hydrogen cyanide its major role is to substantially reduce the time to death. In these experiments the carboxyhemoglobin level at death was slightly reduced from the expected level with exposure to carbon monoxide alone. However, blood cyanide was reduced by a factor of ten from the expected level with exposure to hydrogen cyanide alone. This is another factor (among many other presented) complicating the task of establishing the contribution of cyanide in the death of fire victims, from its analysis in their blood. Finally the role of ethanol intoxication, as it may influence carboxyhemoglobin levels at death, is reviewed. Its role is minor, if any, but the data available on ethanol in brain tissue and blood of fire victims confirmed that brain ethanol level is an excellent predictor of blood ethanol.     

The relationship between chronic ethanol exposure and cigarette smoking in the laboratory and the natural environment

Few studies have examined the association between ethanol use and cigarette smoking topography. In particular, no study has objectively investigated the relationship between chronic ethanol exposure and cigarette smoking. The aim of this study was to quantify the relationship between cigarette smoking and past and current ethanol use. Male and female cigarette smokers (n=77) between the ages of 30 and 65 years were recruited and grouped as a function of their past and current ethanol use. Group 1 (n=18) included subjects who were ethanol abstinent for the 3 months prior to the study and had no history of alcohol abuse (as defined by DSM-III criteria). Group 2 (n=19) included subjects who were current regular ethanol users and had no history of alcohol abuse. Group 3 (n=20) included subjects who were ethanol abstinent and had a history of alcohol abuse. Group 4 (n=20) included current regular ethanol users with a history of alcohol abuse. A history of alcohol abuse was associated with an intensified pattern of cigarette smoking. Significant differences were observed for total daily smoke exposure, cigarette number, puff number, total puff and inhalation volume, and the nicotine, tar and carbon monoxide yields of the cigarettes smoked. Increased expired-air carbon monoxide and serum cotinine levels were also observed. Current ethanol use was not associated with an increased cigarette smoking pattern. These data suggest that alcohol abusers are at greater risk of contracting cigarette-related pathology.Supported by National Institute on Drug Abuse Research Grant No. DA 05013 and DA 02988     

The effect of combined administration of ethanol and gabapentin on rabbit electroencephalographic activity

The central effect of ethanol is mainly connected with the effect on GABAergic, glutamatergic, serotonergic and opioid transmission. The mechanism of gabapentin effect suggests that it may alleviate the rewarding effect of ethanol, which may be used in the treatment of addiction. We decided to examine the interaction of ethanol with gabapentin by a pharmaco-electroencephalographic (EEG) method. The influence of gabapentin on the effect of ethanol on EEG of rabbits (midbrain reticular formation, hippocampus, frontal cortex) was tested. Gabapentin was administered at a single dose (25 and 100 mg/kg orally) or repeatedly twice a day at a total dose of 25 mg/kg for 14 days. Ethanol was injected at a dose of 0.8 g/kg 60 min. after gabapentin treatment. Ethanol caused an increase in the slow frequencies (0.5-4 Hz) in the recording, as well as a marked decrease of the fastest frequencies (13-30 and 30-45 Hz). Gabapentin lead to changes in rabbit EEG recording suggesting an depressant effect on the CNS (increase of slow and decrease of fast frequencies). The effects were less pronounced after repeated doses, which may indicate adaptative changes in the receptors. Gabapentin administered both in a single dose and for 7 days markedly enhanced the effect of ethanol on EEG recordings in rabbits. Repeated doses of gabapentin decrease the sensitivity of the hippocampus to the effect of ethanol.     

Behavioral sensitization and voluntary ethanol drinking in alcohol-preferring AA rats exposed to different regimens of morphine treatment

The purpose of the study was to investigate the effects of three different regimens of morphine treatment on subsequent voluntary ethanol drinking in alcohol-preferring AA (Alko Alcohol) rats. The rats were given morphine subcutaneously either intermittently on alternating days (15 x 10 mg/kg or 5 x 5-20 mg/kg in escalating doses) or subchronically on four consecutive days (3-20 mg/kg/d). Horizontal locomotor activity was monitored after challenges with additional morphine injections (3 mg/kg) ten days and six weeks after termination of the pretreatment to test if behavioral sensitization was induced by repeated morphine administration. Both intermittent pretreatments induced sensitized locomotor response after the first challenge, whereas subchronic injections did not. After the challenge the rats were given a free choice between tap water and 10% (v/v) ethanol solution for four weeks. The rats pretreated and challenged with morphine did not differ significantly in the acquisition of ethanol drinking from the saline-treated controls. In contrast, ethanol drinking was impaired during the first week of ethanol access in the saline-treated rats given a single morphine injection. The second morphine challenge given after the ethanol-drinking phase did not reveal sensitization in any of the groups. The results suggest that pattern of morphine administration rather than the dose or number of exposures to the drug is the most important factor in induction of behavioral sensitization, and that exposure to ethanol may interfere with this process. They also support earlier findings showing that acute morphine may suppress voluntary ethanol drinking, but failed to provide clear evidence for behavioral sensitization to morphine contributing to predilection towards ethanol in AA rats.     

Effect of acute injections of ethanol on lipid and protein-bound sialic acid in mice of different ages

Mice of different age groups (weanling, young adult and aged) were tested for changes in brain lipid- and protein-bound sialic acid (SA) 2 h after ethanol (2 g/kg, i.p.), either as a single dose or after binge dosing of five repeated doses of ethanol spaced 2 h apart. The results clarify our earlier demonstrations that acute ethanol can reduce whole brain SA. Ethanol generally decreased SA of both gangliosidic and glycoprotein origin, with the effect varying with number of doses and mouse age. Single-dose ethanol decreased both lipid-bound and protein-bound SA in young adults and decreased lipid-bound SA in aged mice. There was no effect on lipid-bound SA in weanlings, but weanlings did have a 72% decline in protein-bound SA. Repeated injections in young adults did not cause the SA decrease seen with acute injection. In both weanling and aged mice, however, repeated injections did cause large decreases in both lipid- and protein-bound SA. Small, but statistically significant, changes also occurred in free SA. Ethanol increased free SA in singly-dosed young adults and in multiply-dosed aged adults, while causing a distinct decrease in singly-dosed weanlings.     

Effects of concentration of ethanol injected intraperitoneally on taste aversion,body temperature,and activity

Levels of ethanol-induced conditioned taste aversion and hypothermia were found to be directly related to the concentration of fixed amounts of ethanol injected i.p. in a range of doses (1.0–1.8 g/kg) and concentrations (8–32% v/v) commonly used in behavioral studies. No effect of ethanol concentration on locomotor activity was obtained. The results of blood-ethanol determinations indicate that a given dose of ethanol is absorbed more rapidly, and thus reaches greater peak levels, when injected in a higher concentration. Thus ethanol dosage might be better manipulated by varying the volume of a single concentration rather than by altering concentration. In this way, dose-response data will not be obscured by concentration-induced differences in absorption.     

Reinforcement with intragastric infusions of ethanol: blocking effect of FLA 57

Suppression of oral intake of ethanol by FLA 57 has been reported for rats and was attributed to an inhibition of dopamine beta-hydroxylase. We have demonstrated the ability of FLA 57 (50 mg/kg, IP) to suppress bar-pressing for intragastric (IG) delivery of doses of ethanol (25 mg/kg). This indicates that the effect on oral intake of ethanol may not be attributed to a taste factor, e.g., a decreased palatability of the ethanol solution. The same dose of FLA 57 did not suppress responding for IG doses of sweet milk. Thus, there was not an impairment of appetitive behavior in general through some nonspecific depressant or toxic action. Furthermore, the primary reinforcing action of ethanol, when used to establish a buzzer as a conditioned reinforcer through repeated pairings, was blocked if FLA 57 was given before pairings. This was evidenced by a failure of such rats to bar-press above the baseline level in a later test of conditioned reinforcement, which contrasted with the increased responding seen for rats receiving saline instead of FLA 57 before ethanol. These data support the previous findings on oral ethanol and confirm that FLA 57 can impair the mechanism by which ethanol produces positive reinforcement in rats.