Effects of moderate chronic ethanol consumption on hippocampal nicotinic receptors and associative learning

A number of studies have reported that ethanol exposure induces changes in different brain systems. The hippocampus is a brain region that is very vulnerable to ethanol exposition, which functionally results in impairment of learning and memory processes reported in heavy drinkers. Hippocampal nicotinic receptors are involved in learning and memory. In this study, we determined the effects of ethanol on the main hippocampal subtypes of neural nicotinic receptors (α7 and α4β2) in rats non-selected for alcohol consumption, in order to check for possible changes on these receptors that could be linked with alterations in learning acquisition. Binding assays were carried out with [³H]methyllycaconitine ([³H]MLA) to study the α7 and [³H]nicotine to study α4β2 receptors. Auto-shaping, continuous ratio and extinction procedures were used as behavioral tests. The results show that moderate chronic ethanol consumption for 10 weeks produces: (a) a decrease of both hippocampal nicotinic receptor subtypes without alterations in affinity; (b) no differences in behavioral performance between control rats and ethanol-drinking rats in auto-shaping and continuous ratio; (c) an improvement of performance of extinction paradigm. These results indicate that chronic ethanol consumption, at moderate levels, induces changes in hippocampal nicotinic receptors but does not impair acquisition and performance of new associative learning and even improves some kind of paradigms. These results may have implications in the biochemical basis of interactions between alcohol and nicotine and the effects of these drugs on behavior.     

Effects of chronic social stress during lactation on maternal behavior and growth in rats

Maternal mood disorders such as depression and chronic anxiety can negatively affect the lives of not only mothers, but also of partners, offspring, and future generations. Chronic exposure to psychosocial stress is common in postpartum mothers, and one of the strongest predictors of postpartum depression is social conflict. The objective of the current study was to evaluate the effects of chronic social stress (CSS) during lactation on the maternal behavior (which consists of maternal care and aggression toward a novel conspecific) of lactating rats, as well as on the growth of the dams and their offspring. It was hypothesized that chronic daily exposure to a novel male intruder would alter the display of maternal behavior and impair growth in both the dam and offspring during lactation due to the potentially disruptive effects on maternal behavior and/or lactation. The data indicate that CSS during lactation attenuates maternal care and the growth of both dams and pups, and increases self-grooming and maternal aggression toward a novel male intruder. These results support the use of CSS as a relevant model for disorders that impair maternal behavior and attenuate growth of the offspring, such as postpartum depression and anxiety.     

Effect of chronic ethanol administration on intermale aggression in rats

An experiment was performed to study the effect of chronic ethanol administration on intermale aggression in rats using a 24-hour resident-intruder test. During the resident-intruder test residents displayed virtually all of the agonistic behaviors, and intruders displayed virtually all of the defensive behaviors. Intruders treated with ethanol displayed more defensive behavior and elicited more agonistic behavior than control intruders. Twenty minutes into the resident-intruder test intruders showed the greatest increase in corticosterone (338% vs. 129%), while residents showed the greatest increase in testosterone (103% vs. 18%). On the 2nd day of the resident-intruder test intruders lost more weight than residents (21.5 g vs. 10.2 g). Plasma corticosterone levels remained elevated for the intruders, and in particular for those intruders displaying defensive behaviors regardless of the resident's behavior. Plasma testosterone levels remained elevated for those residents that were paired with intruders that displayed defensive behaviors regardless of the resident's behavior. The frequency and severity of biting attacks by ethanol residents was significantly greater than that of control residents. In addition, the locus of biting attack shifted from the upper back of intruders paired with control residents to the flanks, tail, lower feet, and ventral surface on intruders paired with ethanol residents.     

Effects of prenatal ethanol exposure on juvenile play-fighting and postpubertal aggression in rats

The effects of prenatal ethanol exposure on juvenile play-fighting and postpubertal aggressive behavior in rats were longitudinally assessed in the context of more conventionally applied physical and behavioral measures. Pregnant animals were treated with either 2 gm/kg/day ethanol or isocaloric sucrose over gestation Days 6-19. Reproduction and somatic variables included maternal weight over gestation, offspring weight over Days 1-90, and age at eye opening and incisor eruption. Behavioral variables consisted of negative geotaxis, olfactory discrimination, activity, juvenile play-fighting, and postpubertal aggression. Ethanol offspring had lower birth weights, but there was no significant prenatal treatment effect on subsequent offspring weights or on any other reproductive or somatic variable. Both male and female ethanol-exposed offspring exhibited more play-fighting responses when paired with same-sex controls. Postpubertal aggression levels were assessed in males only. Ethanol-exposed offspring were more aggressive than controls and there was a significant positive correlation between play-fighting and postpubertal aggression ranks. No other behavioral measures discriminated between prenatal treatment groups and none were significantly correlated with either play-fighting or postpubertal aggression rank. The results are consistent with the position that juvenile play-fighting and postpubertal aggression are subserved by common substrates. They also are consistent with predictions derived from the hypothesis concerning a response-inhibition deficit as an effect of prenatal ethanol exposure on behavior.     

Effects of negative incentive shifts in food reward on rats' consumption of concurrent ethanol solutions

Frustration stress, typically operationalized as the unexpected loss of reinforcement, has been shown to engender substance use. Abrupt reductions in reinforcer magnitude likely also function as frustration stressors. These negative incentive shifts were previously shown to produce tap‐ and sweetened‐water drinking in rats. The purpose of this study was to investigate whether these shifts in food reward would occasion oral ethanol self‐administration. Nine male Long‐Evans rats operated on a two‐component multiple fixed‐ratio schedule with signaled components producing either a large (4 pellets) or small (1pellet) reinforcer. Components were pseudorandomly arranged to present 4 transitions between past and upcoming reinforcer magnitudes: small‐to‐large, small‐to‐small, large‐to‐large, and large‐to‐small (negative incentive shift). Experiment 1 investigated the effects of negative incentive shifts on consumption of concurrent, freely available 10% sucrose, 10% sucrose plus 10% ethanol, and following sucrose fading, 10% ethanol. Experiment 2 entailed continuation of schedule contingencies with a dose manipulation of 4 ethanol concentrations (0, 5, 10, and 20%) to assess dose‐dependent differences in transition‐type control and consumption. A lever‐press extinction condition was then conducted with 10% ethanol availability. In this novel model of frustration stress, negative incentive shifts prompted ethanol self‐administration at each dose investigated, whereas the other transitions did not.     

The effect of companion on consumption of ethanol solution in cats

Social influences on drinking ethanol solution were studied in two cats (“drinkers”) who voluntarily drank small amounts of 10% ethanol solution in milk and three other cats (“nondrinkers”) who served as companions to the drinkers. A 15-minute sesion was conducted daily in a compartment divided into two even parts with a transparent Plexiglass partition. The cats were introduced to the compartment either singly or in pairs. Each pair consisted either of two drinkers or one drinker and one nondrinker. Each cat of the pair was placed in one part of the compartment; the cats could see each other, but they could not make physical contact. Each drinker was offered 10% ethanol solution in milk, while each nondrinker was given plain milk, and the amount of consumption was measured. A series of five to ten sessions with a drinker was followed by a series of sessions with a nondrinker or with no companion. There were a total of 13 series of sessions for each drinker. A statistical analysis of the data showed that, in most series, the mean amount of consumption of ethanol solution was significantly higher in the presence of a companion (either drinker or nondrinker) than in its absence.     

Effects of ethanol on reinforced variations and repetitions by rats under a multiple schedule.

Response sequences emitted by five Long-Evans rats were reinforced under a two-component multiple schedule. In the REPEAT component, food pellets were contingent upon completion of a left-left-right-right (LLRR) sequence on two levers. In the VARY component, pellets were contingent upon variable sequences (i.e., a sequence was reinforced only if it differed from each of the previous five sequences). The rats learned to emit LLRR sequences in the REPEAT component and variable sequences in VARY. Intraperitoneal injections of ethanol (1.25, 1.75, and 2.25 g/kg) significantly increased sequence variability in REPEAT, thereby lowering reinforcement probability, but had little effect on sequence variability in the VARY component. These results extend previous findings that alcohol impairs the performance of reinforced repetitions but not of reinforced variations in response sequences.     

Effects of ethanol withdrawal on muricidal behavior

When naive rats of our colony were individually housed for 1 month with free access to laboratory chow and water as drinking fluid, 6% exhibited muricidal behavior. When naive rats of the same colony were similarly housed but received ethanol 20% in water as the sole source of drinking fluid (ll.5 g ethanol/kg/day), the percentage of killer rats was the same. However, when the rats were housed in similar conditions and submitted to a 1-day ethanol withdrawal, the percentage of muricidal rats increased to 25%. Ethanol intake in the same conditions as described above did not change muricidal behavior of spontaneous killers and did not induce killing behavior in nonkiller animals. GABA-mimetic agents administered IP blocked ethanol withdrawal-induced killing behavior as well as spontaneous muricidal activity.     

The effect of ethanol treatment on social behavior in male rats

The effect of 0.50 g/kg of EtOH in male rats interacting with a stimulus male juvenile in a newly developed test of social interaction was examined. The adult male rats were treated with EtOH (8.0 to 12.0 g/kg/day) or equicaloric dextrin maltose for 2 weeks (studies 1 and 2) or 8 weeks (study 3) and social interaction was assessed both before and after chronic drug treatment was ended in study 1 and after chronic drug treatment was ended in studies 2 and 3. It was found that prior to chronic drug treatment, in study 1, 0.50 g/kg of EtOH increased both aggressive behavior and time spent interacting with the stimulus juvenile male from the first presentation of the juvenile to the second presentation (20 min apart) while saline injection decreased it. After chronic drug treatment was ended, in study 1 animals treated chronically with EtOH were more aggressive when they were not intoxicated than when they had been treated with 0.50 g/kg of EtOH. In studies 2 and 3, after chronic drug treatment was ended, aggressive behavior and time spent interacting with the juvenile were greater in the animals treated chronically with EtOH, regardless of whether they were injected with saline or 0.50 g/kg of EtOH. The results of these studies showed that chronic EtOH treatment can produce long-lasting changes in social behavior after drug treatment is over and can alter the animal's normal response to EtOH in a social setting.     

Effects of self-monitoring and feedback on residential electricity consumption

Prior research has indicated that frequent feedback could reduce residential electricity consumption by 10% to 15%. However, because feedback was primarily given in written form, this procedure might not be practical. The present study evaluated a potentially more practical feedback procedure during peak-use periods with high electricity consuming households. The study was conducted during the winter in an upper-middle class neighborhood of almost identical, all-electric townhouses (N = 71) that averaged about 170 KWH per day per household for a monthly bill of over $200. Twelve households received daily written feedback. Sixteen households (self-monitoring) were taught to read their outdoor electricity meter and to record KWH used every day. A comparison group was composed of 14 households that had volunteered to participate and 29 others that had only given permission to have their meters read. During a 1-month period that the procedures were in effect, the feedback group reduced consumption by 13% and the self-monitoring group by about 7%. These reductions, relative to the comparison group, were maintained during an early spring 1-month follow-up period and, to a lesser extent, during a 6-week warm spring period. Self-monitoring participants were highly reliable and persistent meter readers. Reductions in electricity use were reported by households to be largely attributable to lowering of the heat thermostat, and large monetary and KWH savings were found. Techniques to make self-monitoring cost-effective important components of the self-monitoring procedure, methods to apply self-monitoring more broadly, and plans to combine behavioral procedures with physical technology are discussed.     

Differential ethanol olfactory experiences affect ethanol ingestion in preweanlings but not in older rats

Preweanling (21 days old) and adult (60-80 days old) rats were exposed to ethanol odor either paired with the early stages of apomorphine-induced toxicosis, paired with the recovery from toxicosis, or unpaired with the induction of distress. Twenty four hours later, ethanol preferences were measured in a spatial olfactory test (ethanol vs lemon odor) or a drinking test (5.6% v/v ethanol vs 0.25% w/v citric acid solutions). During the olfactory test both young and adult rats expressed substantial ethanol odor aversions when previously exposed to this odor paired with toxicosis. However, changes in ethanol intake became apparent only in preweanling subjects. Preweanlings which received the ethanol odor paired with illness drank significantly less of the ethanol solution relative to controls, while subjects experiencing the odor paired with recovery from distress significantly increased their consumption of the ethanol solution. These prior aversive and appetitive olfactory experiences had no effect upon ethanol intake in adult rats. These results implicate both an ontogenetic and a sensorial factor in the regulation of ethanol intake.     

Effects of posttraining ethanol on an appetitive task

The present study examined the effects of posttraining ethanol administration upon retention of an appetitive task using a variety of retention behaviors associated with the task. Male C57BL/6J mice were individually trained to find a cheese pellet placed in the corner of an open field. Five behavioral measures were used including locomotor activity counts, rearings, grooming episodes, approaches to the cheese pellet, and latency to consume the cheese pellet. Immediately after training, mice were injected intraperitoneally with saline or 2.0 g/kg of ethanol and then returned to their home cage in which four "intruder" mice were added for 2 h after training. On subsequent testing days (1, 6, 14, and 51 days posttraining), mice were returned to the original training environment and the five behaviors were measured. Both saline- and ethanol-treated mice habituated to the initially novel test environment at similar rates as indicated by decreased exploratory behavior (locomotor activity and rearings). In contrast, a divergence in the latency to consume the cheese pellet was observed: Saline-treated mice behaved as though the cheese was rewarding (decreased latency to eat the pellet), while the ethanol group behaved as though the cheese was aversive (increased latency to eat the pellet). Taken with previous studies, these results demonstrate that posttraining ethanol can have strikingly different effects on retention depending on the task, the measure of retention used, and the underlying neural structures involved.     

Influence of rearing conditions on voluntary ethanol intake and response to stress in rats

The effects of exposure to four environmental rearing conditions on subsequent voluntary ethanol intake and response to immobilization stress were examined. Male weanling rats were reared in an enriched environment, with a female partner, with a male partner, or individually, for 90 days. At 111 days of age, voluntary consumption of ethanol in increasing concentrations (3 to 9%, v/v) was assessed. Following the ethanol-exposure period, rats were randomly divided into stressed and nonstressed groups and exposed to 3 h of immobilization. Results indicated that the enriched animals consumed greater amounts of ethanol as compared to all other groups, suggesting that the enriched environment and not handling, housing conditions, or the presence of another male or female is responsible for the observed increase in ethanol drinking behavior. Ulcer data indicated that among environmentally enriched rats, ethanol attenuated stress ulcer development relative to their non-ethanol-exposed but stressed controls. In nonstressed enriched rats, ethanol alone exacerbated stomach damage. We suggest that environmental rearing conditions markedly influence the complex interaction between ethanol intake and the response to stress.     

The effect of chronic caffeine consumption on urinary incontinence in psychogeriatric inpatients

Abstract

Urinary incontinence is a common problem in psychiatric settings, particularly among psychogeriatric patients. In view of the known diuretic action of caffeine, the present study assessed the effect of tea and coffee consumption on level of incontinence in selected psychogeriatric inpatients. A total of 14 patients participated in the study which employed a combined “withdrawal” and “multiple-baseline across subjects” design to examine the effect of alternating phases of caffeine exposure and abstinence on frequency of daytime and nighttime incontinence. Incontinence levels were significantly reduced during periods of caffeine abstinence relative to periods of chronic caffeine exposure. The hypothesis that observed reductions in incontinence may have been due to accompanying reductions in fluid intake was examined but not supported.