Behavioral effects of ethanol in animals: age differences and age changes

Impact of acute ethanol exposure on body temperatures in aged, adult and adolescent male rats

The mean population age of the United States continues to increase, and data suggest that by the year 2060 the population of people over the age of 65 will more than double, providing a potentially massive strain on health care systems. Research demonstrates individuals 65 and older continue to consume ethanol, often at high levels. However, preclinical animal models are still being developed to understand how ethanol might interact with the aged population. The current experiments investigated differential body temperature responses in aged rats compared to adult rats and adolescent rats. Aged (19 months of age), adult (70 days of age), or adolescent (30 days of age) male Sprague Dawley rats were administered 1.0 g/kg, 2.0 g/kg, or 3.0 g/kg ethanol, intraperitoneally (i.p.), in a balanced Latin square design. Prior to ethanol administration, a core body temperature via an anal probe was obtained, and then repeatedly determined every 60 min following ethanol exposure for a total of 360 min. In addition, a blood sample was obtained from a tail nick 60, 180, and 300 min following the ethanol injection to investigate the relationship of ethanol levels and body temperature in the same animals. Aged rats had significantly greater reductions in body temperature compared to either adult or adolescent rats following both the 2.0 g/kg and 3.0 g/kg ethanol injection. Additionally, adolescent rats cleared ethanol significantly faster than aged or adult animals. These experiments suggest body temperature regulation in aged rats might be more sensitive to acute ethanol compared to adult rats or adolescent rats. Future studies are needed to identify the neurobiological effects underlying the differential sensitivity in aged rats to ethanol.

I can't drink what I used to: The interaction between ethanol and the aging brain

The population of most countries is increasing and the United Nations predicts that by the year 2050 those over the age of 60 years old will increase from 900 million individuals to approximately 2.1 billion individuals (United Nations, 2015). The increase in the number of older individuals will place a strain on many national health care systems making it important to investigate behaviors in the aged that may negatively impact general health in this demographic. Recent work has shown that older adults consume alcohol, often at levels that exceed the legal limit of intoxication. Unfortunately, consumption of high levels of ethanol in the older population is associated with many health consequences and may negatively impact the brain. Given ethical constraints found in many biomedical studies, animal models are needed to investigate the possible negative impact of high ethanol use in aged populations. However, few studies have investigated the effect of ethanol exposure in aged animals compared to ethanol exposure in younger animals and consequently the impact of ethanol in the aged population is not well understood. The current review summarizes initial work establishing the impact of ethanol in aged animals. The reviewed research studies support the working hypothesis that ethanol exposure produces significantly greater effects in aged animals compared to younger animals on many, if not all, behavioral tasks. In addition, the review proposes several initial, promising avenues of research to explore the neurobiological mechanisms that underly greater effects on ethanol-induced ataxia, cognition and sleep time. It is hoped that this effort will not only lead to a better understanding of behaviors impacted by ethanol in aged animals, but also improve the understanding brain mechanisms of the reported increased sensitivity to ethanol in the aged population.

The effects of acute alcohol on motor impairments in adolescent, adult, and aged rats

Acute alcohol exposure has been shown to produce differential motor impairments between aged and adult rats and between adolescent and adult rats. However, the effects of acute alcohol exposure among adolescent, adult, and aged rats have yet to be systematically investigated within the same project using a dose-dependent analysis. We sought to determine the age- and dose-dependent effects of acute alcohol exposure on gross and coordinated motor performance across the rodent lifespan. Adolescent (PD 30), adult (PD 70), and aged (approximately 18 months) male Sprague-Dawley rats were tested on 3 separate motor tasks: aerial righting reflex (ARR), accelerating rotarod (RR), and loss of righting reflex (LORR). In a separate group of animals, blood ethanol concentrations (BEC) were determined at multiple time points following a 3.0 g/kg ethanol injection. Behavioral tests were conducted with a Latin square repeated-measures design in which all animals received the following doses: 1.0 g/kg or 2.0 g/kg alcohol or saline over 3 separate sessions via intraperitoneal (i.p.) injection. During testing, motor impairments were assessed on the RR 10 min post-injection and on ARR 20 min post-injection. Aged animals spent significantly less time on the RR when administered 1.0 g/kg alcohol compared to adult rats. In addition, motor performance impairments significantly increased with age after 2.0 g/kg alcohol administration. On the ARR test, aged rats were more sensitive to the effects of 1.0 g/kg and 2.0 g/kg alcohol compared to adolescents and adults. Seven days after the last testing session, animals were given 3.0 g/kg alcohol and LORR was examined. During LORR, aged animals slept longer compared to adult and adolescent rats. This effect cannot be explained solely by BEC levels in aged rats. The present study suggests that acute alcohol exposure produces greater motor impairments in older rats when compared to adolescent and adult rats and begins to establish a procedure to determine motor effects by alcohol across the lifespan.

Moderate, long-term, alcohol consumption potentiates normal, age-related spatial memory deficits in rats

A modified "Samson" sucrose fading procedure was used to establish voluntary consumption of a 20% ethanol (EtOH) solution in male Sprague-Dawley rats for 18 consecutive months. Intakes were stable over the life span, and corresponded to the moderate to high levels of intake typically observed in human "social" drinkers and alcoholics. The Morris Water Maze (WM), Olton Radial Arm Maze (RM), and a "balance beam" test were used to assess the effects of alcohol and aging on spatial memory and motor function. Aged EtOH-consuming rats (AGED/ALC) demonstrated impaired task acquisition, relative to aged controls (AGED), not reaching criterion performance in either spatial memory task even when given four additional days of training. AGED/ALC rats scored significantly lower on percent correct out of the first eight arm entries, and committed more perseverative errors in the RM. There were no significant performance differences between AGED and AGED/ALC rats on a balance beam test of fine motor coordination and equilibrium, suggesting that deficits observed in the RM and WM were not related to differential motor functioning. These results demonstrated that long-term, moderate, oral self-administration of EtOH, within the range typically consumed by humans, had adverse effects on spatial memory in rats, and that such a pattern of EtOH consumption seemed to exacerbate the decline in cognitive functioning associated with normal aging.

Decreased sensitivity to the hypnotic effects of ethanol early in ontogeny

Sensitivity to the hypnotic effects of ethanol was examined in Sprague-Dawley male and female rats at 16, 26, 36, 46, 56, or 96 days postnatally. Following administration of 3.5, 4.0, 4.5, or 5.0 g/kg of a 17% v/v ethanol solution, sleep times were recorded and blood alcohol levels (BALs) and brain alcohol levels (BrALs) were measured upon awakening. In addition to examining ethanol sleep time during ontogeny, data were used to estimate acute tolerance (indexed by the slope of the linear regressions of waking BALs and BrALs as a function of dose) and initial brain sensitivity to ethanol (indexed by calculating the y-intercept from the linear regression of BrALs as a function of sleep time). The results showed a marked increase in sensitivity to ethanol hypnosis during ontogeny, with young animals exhibiting shorter ethanol-induced sleep times and high waking BALs and BrALs. This ontogenetic increase in ethanol sensitivity was associated with a developmental decline in acute tolerance, with acute tolerance being most pronounced at postnatal day (P) 16 and evident only up to P36. Initial sensitivity conversely increased with age, with P16 pups showing lower initial brain sensitivity to ethanol than at all other ages. Gender differences emerged in adulthood, with males sleeping significantly longer than females at P56 and P96. These findings suggest that the marked insensitivity of young animals to the hypnotic effects of ethanol is related to both pronounced acute tolerance, as well as reduced initial brain sensitivity to ethanol early in life.

The discrimination and durability of an ethanol cue in young and mid-aged female mice

Young adult (6 months) and mid-aged (12 months) C57BL/6 mice both learned to discriminate ethanol (ETOH, 1.0 g/kg) although criterion performance occurred later for mid-aged mice. ETOH discrimination improved with increasing dose (0.25-1.0 g/kg) and the dose-response function was unaffected by age. The ETOH cue had declined by 40 min postinjection for young mice not unlike a previous report for young rats. In contrast, the ETOH cue remained discriminable at 40 min for mid-aged mice, an effect perhaps due to their slower rate of ETOH metabolism and accountable for the previously reported reduction in ethanol consumption by mid-aged mice. Retention tests and reacquisition training both indicated that the ETOH cue can be retained by both age groups for at least 60 days without discrimination training or food deprivation. The present study suggests that the ethanol discriminative cue in mid-aged mice does not differ from that in young adult mice in potency but is more long lasting, the latter perhaps being related to their reduced ethanol consumption. Of significance from a therapeutic perspective, is that the ETOH cue remained discriminable for 2 months in both age groups (i.e., approximately 1/12 of their total life span).

Differential sensitivity of NMDA receptor-mediated synaptic potentials to ethanol in immature versus mature hippocampus

Pharmacologically isolated, NMDA receptor-mediated population EPSPs (pEPSPs) were evoked from area CA1 of hippocampal slices using electrical stimulation of the Schaffer collateral/commissural fiber pathway. Slices were prepared from rats aged 20-25 or 80-100 days. The inhibitory effects of a range of ethanol concentrations were assessed. While ethanol antagonized NMDA-mediated pEPSPs in slices from both age groups, it was significantly more potent against pEPSPs from immature versus mature hippocampi. In slices from mature animals, significant and consistent reduction of pEPSPs was observed only with the highest ethanol concentration (100 mM), whereas 10, 30, or 100 mM significantly reduced the amplitude of pEPSPs in slices from immature animals. These results indicate that NMDA-mediated synaptic activity in the hippocampus is more sensitive to the effects of ethanol in immature versus mature animals.

Chronic ethanol effects on glycoconjugates and glycosyltransferases of rat brain

We studied the effects of a four week administration of low doses of ethanol on glycoconjugates of the synaptosomal and microsomal fraction prepared from the brain of rats aged 2 and 7 months. Synaptosomes were the more sensitive to ethanol treatment. Total lipid bound sialic acid and neutral glycolipid and glycoprotein content were significantly reduced only in the synaptosomal fraction, with greater differences in the younger age, while glycoprotein sialic acid was not affected. None of the above differences were statistically significant in the microsomal fraction. Ganglioside pattern was altered only in the 2 month rats, showing a reduction of GM1 and GM1a in the synaptosomal fraction and of GD1a in the microsomal fraction. UDP-Gal: asialo-mucin galactosyltransferase, UDP-Gal: GlcCer galactosyltransferase, and UDP-Gal: GM2 galactosyltransferase activities were decreased and could account for the observed modifications in glycoconjugate content and distribution.

Absence of impairments in spatial and temporal discrimination learning in Lewis rats after chronic ethanol consumption

Many studies reported that chronic ethanol consumption leads to cognitive dysfunction in rodents. It has been suggested that the effects of chronic ethanol consumption resemble those of aging because of the behavioral and neurochemical similarities between the two processes. The present study examined the effects of a chronic ethanol treatment (20% aqueous solution) in Lewis rats on performance in three different tasks: the Morris spatial navigation task, a cone-field task, and a temporal discrimination task. Although an age-related deficit was found in water escape learning, chronic ethanol consumption did not affect the performance of adult and old rats. The results of this experiment were, however, not conclusive. No differences between old control and ethanol-treated rats were found for spatial (cone-field task) and temporal discrimination learning. However, old ethanol-treated rats showed a transient tendency to perseverate in the temporal discrimination task. The present results are at variance with the generally found cognitive impairments after chronic ethanol consumption using aqueous solutions. It is suggested that the effects of ethanol could be related to strain of rat, task complexity, method of ethanol administering, and housing conditions and may explain the discrepancy between results.

Tolerance to effects of high doses of ethanol: 1. Lethal effects in mice

Male Swiss Webster mice were injected with ethanol doses ranging from 6.5-10.5 g/kg (20% w/v, IP). Survival time distribution revealed three waves of deaths with peaks around 5 min, 300 min, and 33 h. There were two windows with very low density of probability of death between 30-130 min and between 22-25 h following lethal injections. This time structure of the probability density function did not significantly depend upon ethanol overdose, novelty of the experimental environment, or prior injections of saline and/or 3.5 g/kg ethanol. Injections of high doses of ethanol in BALB/c mice showed that this strain of mice was more sensitive to ethanol-induced lethality (LD50 = 6.6 g/kg) and over 99% of deaths occurred between 5-200 min following injections of the doses from 5.5-7.5 g/kg. Preexposure to ethanol increased tolerance to ethanol-induced lethality. LD50 increased from 8.1 g/kg (at 24 h following lethal injections in ethanol-naive Swiss Webster mice) to 8.5 and 9.0 g/kg in mice following four and eight injections of 3.5 g/kg ethanol, respectively. In BALB/c mice, eight prior injections of 3.5 g/kg ethanol increased LD50 also slightly but significantly to 7.15 g/kg. The results suggest that: a) Ethanol-induced lethality is not a unitary phenomenon and that deaths that occurred within distinct waves probably have different causes; b) mice strains have different susceptibility to different causes of ethanol-induced deaths; c) preexposure to 3.5 g/kg ethanol results in significant but small increase in tolerance to ethanol-induced lethality.

Age related changes in functions and physicochemical properties of rat jejunal brush border membrane after chronic ethanol administration

1. We investigated the chronic effects of a 4 week treatment with ethanol on functions and physicochemical properties of BBM of young and adult rats (2 and 7 months old respectively). 2. In the ethanol treated groups the cholesterol/phospholipid and the protein/lipid ratios as well as the D-glucose uptake and lactase specific activity and Vmax were increased. In spite of a minor alcohol consumption the adult group was the more affected. 3. Membranes from the ethanol fed rats were less fluid and more tolerant to the in vitro addition of ethanol.

Interaction of aging and lifelong ethanol ingestion on ethanol-related behaviors and longevity

The interactions of aging and long-term voluntary ethanol consumption were studied in the alcohol-preferring AA (Alko Alcohol) rats. The mean daily ethanol intake was 6.45 +/- 0.31 g/kg/day (mean +/- SE) at the beginning of the exposure at 3 months of age. The control animals were given only food and water ad libitum. There was no difference in survival or weight gain between the control and ethanol groups. When tested for voluntary ethanol intake at the age of 24 months, the rats in the ethanol group consumed significantly more ethanol than the controls. The two groups did not differ in ethanol-induced motor impairment, sleep-time, or hypothermia, nor in the rate of ethanol elimination. The 24-month-old animals, however, showed higher sensitivity to ethanol than the 3-4-month-old rats in the sleep-time test. It is concluded that the feeding regimen used in this study did not produce any detectable interactions between ethanol and the aging processes in the AA rats.

The effect of repeated withdrawal episodes on subsequent withdrawal severity in ethanol-treated rats

Male rats were given ethanol via an intragastric catheter (8.0-11.0 g/kg per day) for either 8 weeks daily or for four 2-week periods with a 2-week period of no drug treatment intervening between each period of ethanol administration (binge). Older rats were administered ethanol for 2 weeks, to assess the effects of age on ethanol withdrawal as age can alter an animal's sensitivity to ethanol. The presence of physical dependence during withdrawal was assessed on an open field test. Rats that experienced repeated episodes of withdrawal (binge) showed more severe withdrawal signs in successive withdrawal episodes. Older animals showed more severe signs of withdrawal than younger animals after 2 weeks of ethanol treatment. The results of this study lend support to the hypothesis that the experience of withdrawal from ethanol can alter an animal's subsequent response to the drug. Aging appeared to contribute to this effect, but further work is needed to delineate its role.

Effects of route of administration of ethanol on high-speed reaction time in young and old rats

The blood ethanol concentrations (BECs) and reactive capacity of young (8 months) and old (24 months) male Fischer 344 rats were compared at 5, 10, 20, 45, 65, and 90 min following the administration of ethanol (EtOH). The time-dependent effects of intragastric intubation (IG; 3 g/kg) and intraperitoneal injection (IP; 1.5 g/kg) of EtOH (20% w/v) were determined. Subsequent to IG delivery, BECs rose most rapidly within the first 20 min, but did not reach peak levels until 90 min for both young (240 mg/dl) and old rats (250 mg/dl). Following IP injections, BECs escalated within 5 min to 250 mg/dl in the young, to 175 mg/dl in the old, and declined gradually to a stabilized value of 150 mg/dl (young) and 130 mg/dl (old). The old rats never achieved the high BECs seen in the young. Reactive capacity, a measure of auditory/visual reaction time, was inversely related to BECs. As BECs (IP) declined, performance improved at a similar rate in both age groups, although the old rats' performance was more impaired than that of the young. However, BEC per se was not an adequate predictor of reactive capacity. When EtOH was delivered by IG so that BECs remained high for long periods of time, reactive capacity was far less impaired compared with IP delivery in which comparable BECs were present for only a few minutes. The possibility was noted that behavioral tolerance may have developed during the 90-min post-EtOH period, and that the IP delivery method may disrupt behavior in ways independent of brain ethanol levels.

Membrane effects of ethanol: bulk lipid versus lipid domains

It has been well-established that ethanol fluidizes the bulk lipid of membranes and that this effect may alter cell function and be involved in ethanol sensitivity and tolerance. This hypothesis has been supported in several studies, however, there is also a considerable amount of data that do not support such an explanation, e.g., direct effect of ethanol on proteins, other membrane acting drugs, temperature effects, effects of ethanol on aged membranes and inconsistent effects of chronic ethanol consumption on lipid content. This review examined the bulk membrane fluidization hypothesis in light of those data and proposed a modification of the bulk membrane hypothesis that is based on recent data that show that ethanol and other alcohols have a specific effect on the structural properties of different membrane domains. This specific effect of ethanol is discussed within the context of how changes in fluidity of domains may alter membrane function.

Circadian rhythm of blood ethanol clearance rates in rats: response to reversal of the L/D regimen and to continuous darkness and continuous illumination

Phase relationships of the circadian rhythms of blood ethanol clearance (metabolic) rates and body temperature were studied in rats successively exposed to 4 illumination regimens: LD (light from 0800-2000 hr), DL (light from 2000-0800 hr), constant darkness (DD) and, lastly, constant light (LL). After a 4-wk standardization to each regimen, body temperatures were taken at 9 X 4-hr intervals to establish baseline circadian profiles. One week later, groups (N = 8) received 1.5 g/kg ethanol (i.p.) at 6 equally spaced timepoints during a 24-hr span, when temperatures were again measured. Ethanol clearance rates were estimated from decreasing blood ethanol levels sampled every 20 min from 60-200 min after dosing, and the resultant elimination curves were subjected to cosinor analysis. These studies show for the first time that the high amplitude circadian rhythm in ethanol metabolism persists under constant conditions of illumination (DD and LL), demonstrating that it may well be a truly internal circadian rhythm and not a response to exogenous cues of the light/dark cycle. During both LD and DL, maximal and minimal ethanol clearance rates fell near the end of the dark and light phases, respectively, and followed circadian peak and trough control temperatures by approximately 6 hr. A fixed internal phase relationship between the core body temperature and the circadian rhythm in ethanol metabolism is demonstrated, thus establishing the rhythm in body temperature as a suitable and convenient internal marker rhythm for studies of the metabolism of low-to-moderate ethanol doses. These studies demonstrate that the phase relationships of blood ethanol clearance rate and body temperature can be manipulated by the illumination regimen selected, an observation of both basic and practical importance.

AL721, a novel membrane fluidizer

AL721, which is a novel lipid mixture extracted from egg yolks, is believed to be a therapeutic pharmacologic agent. AL721 interacts with membranes of various types of cells with a common mode of action. AL721 modifies cellular membrane composition and fluidity through passive extraction and/or exchange of cholesterol. Physiologically diminished cell function due to rigidification of its membrane is reversible both in vitro and in vivo by AL721. Fluidization of aged membranes with AL721 has been shown to restore brain serotonin receptor function both in vitro and in vivo. AL721 can also successfully restore deficient immune responsiveness of lymphocytes to mitogen stimulation in aged subjects. Drug tolerance to morphine and ethanol develops upon elevation of the viscosity of neuronal cell membranes in order to counteract the fluidization effect of the drug. Treatment of rigidified cellular membranes with AL721 in vivo can markedly reduce withdrawal symptoms. The virucidal effect of AL721 on the human immunodeficiency virus is believed to operate by lowering of viral membrane cholesterol thus interfering with the binding of the viral antigen to the host cell. Non-toxicity of AL721 is clearly demonstrated in animal and human safety studies.

Ageing and recovery from alcoholism

Fifty-five dependent (DSM-III) male alcoholics, chosen for good social adjustment, were personally followed up about 20 years after their first admission to hospital. The conditions of all the alcoholics were evaluated with a multidimensional diagnostic schedule when first admitted. At the follow-up, 11 were abstainers, 11 reported a change to social drinking via abstinence, and 10 reported a change to social drinking by gradual stages. Improvement after the age of 45 was mainly due to gradual change to social drinking. This type of improvement was in half of the cases attributed to a decreased tolerance for alcohol. In the present sample, there were no indications of any relationship between premature ageing and gradual change to social drinking. It is hypothesised that physiological processes of normal ageing with concomitant changes in reactions to alcohol may be of importance for remission from alcoholism in middle-aged and older alcoholics. The relationships of personality, social factors and the degree of alcohol-dependence to patterns of successful long-term adjustment are discussed.

Effect of alcohol on cellular membranes

Ethanol disrupts the physical structure of cell membranes. The most fluid membranes, including those that are low in cholesterol, are the most easily disordered by ethanol. Although the membrane-disordering effect is small, there is pharmacological, temporal, and genetic evidence that it is important. Animals that are resistant to ethanol intoxication because of their genetic background or because of previous exposure to ethanol are found to have brain membranes that are not easily disordered in vitro. An exception is the increased behavioral sensitivity in aging animals, which is not matched by changes in their membranes. When animals are treated chronically with ethanol, their membranes become stiffer, a response that can be regarded as adaptive. Ethanol may favor the uptake of cholesterol or saturated fatty acids into membranes, thus reducing its own effect.

Age differences in the oxidation of and neural response to ethanol in mice

Male mice (C57BL/6J) from three age groups, 4, 14, and 26 months, were tested to determine their oxidation rate of intragastrically infused ethanol and the response of the centrally mediated jaw-jerk reflex to ethanol challenge. There were no age-related differences in the rate of oxidation of ethanol. However, age differences in ethanol-induced decrement of the jaw-jerk amplitude were significant. The 26 month animals were the most affected, followed by the 4 month group. The middle aged mice (14 month) showed the greatest resistance to the depression induced by ethanol. The results were evaluated with regard to the current hypotheses.

Cross-cultural aspects of alcoholism in the elderly

Thus far, we know relatively little about alcoholism among the elderly across cultures. However, extrapolation from available reports suggests certain common features across cultures. These include an inverse relationship between age and problem-producing dosages, increased risk of elderly alcoholics to trauma, greater efficacy of milieu changes with age, and a concentration of elderly alcoholics in cities. Conversely, certain other aspects of aging that vary across cultures may influence alcoholism in the elderly. These include the biological concomitants of aging, social status and the role of the elderly in the society (including integration or isolation of widowed persons), dealing with problematic behavior in the elderly, and patterns of alcohol use by the elderly. Future strategies for researching alcoholism among the elderly are suggested. It is suggested that cultural norms and values, as well as social policy, ameliorate or exacerbate alcohol-related problems among the elderly.

Increased responsiveness to ethanol with advancing age in rats

Male CD strain rats of three different ages (young-5 months; middle-15 months; old-27 months) were tested for their responsiveness to doses of ethanol sufficient to produce hypothermia or hypnosis. Comparison dosages of ethanol across age groups were based upon the estimated equivalent dilution of the drug into the body water compartments of subjects. In the hypnosis study, there were no statistically significant differences among the groups with regard to the time elapsed until the righting reflex was lost or in total sleep time. However, old animals recovered the righting reflex in the presence of lower blood ethanol concentrations than those observed for young and middle animals, suggesting a greater sensitivity of target tissues to the hypnotic effects of ethanol in old rats. The responsiveness of old rats to the hypothermic effect of ethanol was greater than that of younger rats only when the experiment was conducted at an ambient room temperature of 10 degrees C.

A comparison of the effects of long-term alcohol abuse and aging on the performance of verbal and nonverbal divided attention tasks

The purpose of this study was to assess two versions of the hypothesis that alcohol abuse results in premature aging of the brain and of cognitive functioning. The performances of detoxified long-term alcoholic was compared with that of nonalcoholic controls on three divided attention tasks known to be sensitive to aging. While both forms of the premature aging hypothesis predicted that alcoholics should perform more poorly than controls, the hypotheses differed in their predictions of the interactions between the effects of alcohol and normal aging. The results showed that while all three tasks were sensitive to age, only two were affected by long-term alcohol abuse. On one of the tests affected by both age and alcohol abuse, the performance of both young and old alcoholics was equally impaired whereas on the other, only the older alcoholics had significant difficulties. Based on these findings it was concluded that there was only partial overlap between the effects of alcohol and aging, and that neither of the two forms of the premature aging hypothesis could predict the observed pattern of results.

Ethanol intoxication and withdrawal among three age groups of C57BL/6NNIA mice

Data have not been forthcoming on the effects of chronic ethanol administration on intoxication and severity of withdrawal using animals representative of the life-span of a particular species. The purpose of this study was to examine ethanol intoxication and withdrawal among three age groups (3, 14, 25 months) of C57BL/6NNIA male mice. Ethanol was administered in a liquid diet for 14 days. Pair-fed control groups and laboratory chow groups were also employed. Blood ethanol levels, signs of intoxication and withdrawal, liquid diet consumption, and body weight were measured. Old mice were significantly more intoxicated than younger mice. However, young mice consumed more ethanol as compared to the older mice. Blood ethanol levels did not differ among the three age groups, although variability was high within each age group. The ethanol liquid diet groups did not show a decrease in body weight. Withdrawal was more severe for old animals than younger animals. The greater effects of ethanol observed in the old animals do not appear to be attributable to age differences in blood ethanol levels, amount of ethanol consumed, or body weight loss.

Age differences in ethanol-induced hypothermia and impairment in mice

This experiment examined the effects of ethanol on body temperature and ethanol-induced impairment among three different age groups (8 months, 18 months, and 28 months) of C57BL/6NNIA male mice. Mice were injected intraperitoneally with 3 g/kg ethanol or an equivalent volume of saline. Body temperature, blood ethanol levels, and time when the righting response (RR) was lost and regained were measured. Body temperature also was measured prior to injection and at 30 and 120 min post-injection The aged mice showed less ethanol-induced hypothermia but were impaired longer as compared to the younger mice. Blood ethanol levels at loss and regaining of the RR were lower for old mice than the younger mice. Body temperature for the youngest group was lower at each time of measurement as compared to the older groups. Age differences in body temperature prior to ethanol or saline injection were small and nonsignificant.