Effects of ethyl alcohol on development and social behaviour in the offspring of laboratory mice

Social behavior of offspring following prenatal cocaine exposure in rodents: a comparison with prenatal alcohol

Clinical and experimental reports suggest that prenatal cocaine exposure (PCE) alters the offsprings' social interactions with caregivers and conspecifics. Children exposed to prenatal cocaine show deficits in caregiver attachment and play behavior. In animal models, a developmental pattern of effects that range from deficits in play and social interaction during adolescence, to aggressive reactions during competition in adulthood is seen. This review will focus primarily on the effects of PCE on social behaviors involving conspecifics in animal models. Social relationships are critical to the developing organism; maternally directed interactions are necessary for initial survival. Juvenile rats deprived of play behavior, one of the earliest forms of non-mother directed social behaviors in rodents, show deficits in learning tasks and sexual competence. Social behavior is inherently complex. Because the emergence of appropriate social skills involves the interplay between various conceptual and biological facets of behavior and social information, it may be a particularly sensitive measure of prenatal insult. The social behavior surveyed include social interactions, play behavior/fighting, scent marking, and aggressive behavior in the offspring, as well as aspects of maternal behavior. The goal is to determine if there is a consensus of results in the literature with respect to PCE and social behaviors, and to discuss discrepant findings in terms of exposure models, the paradigms, and dependent variables, as well as housing conditions, and the sex and age of the offspring at testing. As there is increasing evidence that deficits in social behavior may be sequelae of developmental exposure alcohol, we compare changes in social behaviors reported for prenatal alcohol with those reported for prenatal cocaine. Shortcomings in the both literatures are identified and addressed in an effort to improve the translational value of future experimentation.

Teratogenic actions of ethanol in the mouse: a minireview

The deleterious effects of prenatal ethanol exposure have been extensively documented in clinical and experimental studies. This paper provides an overview of work conducted with mice to examine the myriad of adverse consequences that result from embryonic/fetal exposure to ethanol. All of the hallmark features of the clinical fetal alcohol syndrome have been demonstrated in mice, including prenatal and postnatal growth retardation, structural malformations and behavioral abnormalities associated with central nervous system dysfunction. As expected, the severity and profile of effects is related to both dosage level and timing of exposure. In addition, these effects have been demonstrated following acute and chronic exposure, with a variety of routes of administration employed. Furthermore, a number of strains have been used in these studies and the variant response (susceptibility) to the teratogenic actions of ethanol exhibited among different mouse strains support the notion that genetic factors govern, at least in part, vulnerability to these effects of ethanol. More recent studies using mouse models have focused on examining potential mechanisms underlying the full spectrum of ethanol's teratogenic actions.

Permanent neuronal deficits in rats exposed to alcohol during the brain growth spurt

The purpose of this study was to determine whether developmental alcohol exposure could induce permanent neuronal deficits, whether the peak blood alcohol concentration (BAC) influences the severity of the effects, and whether the effects are gender related. Rat pups were reared artificially over postnatal days (PD) 4 through 11 (a period of rapid brain growth, comparable to part of the human third trimester). Alcohol treatments were administered on PD 4 through 9. Patterns of alcohol exposure that produce different peak BACs have been shown to affect differentially the amount of brain weight deficits and neuron loss shortly after the exposure period, so this study investigated whether the pattern of alcohol exposure was also effective in producing permanent deficits. Two groups received a daily alcohol dose of 4.5 g/kg, condensed into either four or two feedings. A third group received a higher daily alcohol dose of 6.6 g/kg administered in 12 uniformly spaced daily feedings. Pups were fostered back to dams on PD 11 and perfused on PD 90. Brain weights were measured, and Purkinje cells and granule cells were counted in each of the 10 lobules of the cerebellar vermis. In the hippocampal formation, cell counts were made of the pyramidal cells of fields CA1 and CA2/3, the multiple cell types of CA4 and the granule cells of the dentate gyrus. The groups receiving the lower daily dose (4.5 g/kg) condensed into either four or two feedings were exposed to higher peak BACs and suffered significant permanent brain weight deficits and neuronal losses, relative to controls. The group receiving the higher daily dose (6.6 g/kg) in continuous fractions had no significant brain weight reductions or neuronal loss. Vulnerability to alcohol-induced neuronal loss varied among regions and cell populations and as a function of peak BAC. In the hippocampus, only the CA1 pyramidal cells were significantly reduced in number and only in group receiving the most condensed alcohol treatment. In the cerebellum, the severity of Purkinje cell and granule cell losses varied among lobules, and Purkinje cell vulnerability appeared to depend on the maturational state of the neuron at the time of the alcohol exposure, with the more mature Purkinje cells being the more vulnerable.

Effect of moderate prenatal ethanol exposure on postnatal brain and behavioral development in BALB/c mice

Prior research had indicated that moderate maternal ethanol consumption during gestation affected the growth of the corpus callosum and anterior commissure in BALB/c mice when measured at day 19 postconception. Our purpose was to assess whether or not this was an enduring effect. Pregnant BALB/cCRBL mice were fed ethanol 10% v/v in the drinking water from days 5 to 26 postconception. Control animals received an isocaloric sucrose solution and were pair-fed to the experimental animals. An additional control group fed laboratory chow ad libitum was included. Using a split-litter design, brain development was assessed on days 26 and 50 postconception and behavioral development of the pups was measured on day 32. The ethanol-treated offspring had lower brain weights at both ages as well as a smaller cross-sectional area of the anterior commissure on day 50, which was significantly related to the smaller brain weight. There was no apparent effect of ethanol on the area of the corpus callosum at either age. Similarly, behavioral development was not affected by the treatment, although eye-opening was delayed in ethanol-treated animals. Measures of maternal behavior indicated that the animals consuming alcohol were more active than those in the control groups. An unexpected finding was that the control group fed sucrose appeared to be adversely affected. The body weight of these pups was lower, as was the area of the corpus callosum at day 50.

Learning retardation and enhanced ethanol preference produced by postnatal pretreatments with ethanol in adult rats

Male neonates of Wistar strain rats were given 0.63-2.50 g/kg/day of ethanol, i.p., for 7 successive days from day 6 to 12 after birth. The acquisition processes of the discriminated lever-press avoidance response (intertrial interval: 25 sec, warning stimuli presentation: 5 sec, foot shock intensity: 110V, 0.5 mA, 50 Hz, AC) were investigated for 20 separate sessions from day 60 after birth. The preference test for ethanol was done beginning at 120 days of age. No significant differences in body weights were detected between saline- and ethanol-pretreated groups. However, learning retardation was observed in all groups pretreated with ethanol. In these groups, slow responses to warning stimuli followed by escape responses from shocks delivered were often observed in early training sessions. An enhanced preference for ethanol was observed in all groups pretreated with ethanol for 7 successive days at maturity. These results suggest the possibility that learning ability and preference for ethanol in adult rats are strongly influenced by pretreatments with ethanol during the early postnatal period.

Behavioural effects of phenobarbitone. 1. Effects in the offspring of laboratory mice

Phenobarbitone at a concentration of 187.5 mg/l in drinking fluid of breeding mice and their offspring after weaning did not affect gestation period, litter size, litter weight or pup development before weaning, although a slight retardation of weight gain after weaning occurred. This level of phenobarbitone given to mice after weaning did not affect weight gain. The average daily intake of phenobarbitone ranged from 30 to 52 mg/kg body weight depending on age and sex. Behaviour of offspring and mice treated after weaning was examined by ethological analysis of encounters between unfamiliar mice of the same sex and treatment group in a neutral enclosure. After lifelong exposure to phenobarbitone mice at 5 and 15 weeks of age showed an increased amount of scanning and exploration of the unfamiliar cage coupled with a decrease of time spent in immobility. Difference from control levels was more pronounced at 15 than at 5 weeks of age, in part because controls showed more immobility and explored less as they matured. No behavioural changes were detected in mice treated with this level of phenobarbitone after weaning. Lifelong exposure to phenobarbitone did not affect agonistic behaviour in pair-housed males at 30 weeks of age, and under these circumstances no longer stimulated exploration to a significant extent.

Effects of ethyl alcohol on behaviour in nursing female mice

Effects of administering 10% ethyl alcohol as drinking fluid to mice during pregnancy and lactation have been examined by ethological analysis of behaviour of nursing females in their home cages at 1 day, 5--7 days, and 12--14 days postpartum. The treatment with alcohol did not affect gestation period or litter size, and fluid intake of treated mice remained similar to that of controls, the average intake of alcohol amounting to 29 mg/g body weight during lactation. Increase in frequency of exploration at 1 day postpartum was the only significant behavioural effect of alcohol on the nursing female mice. Duration of Non-Social Behaviour was unaltered, and no effects of the treatment on Maternal Behaviour or on Social and Sexual Investigation of male partners could be demonstrated. Behaviour of nursing females changed with increase in age of their pups. This occurred to a similar extent in treated and control animals. Maternal and Non-Social Behaviours declined in frequency as the pups became older although the time spent in these behaviours remained fairly constant. Social Investigation of the male partner declined both in frequency and duration while females were nursing their pups.

Growth and behavioural effects of ethyl alcohol on the offspring of mice; a comparison with its short-term actions

Ten percent ethyl alcohol as drinking fluid of breeding mice did not affect gestation period, litter size or litter weight. Alcohol was secreted in milk, and weight gain up to weaning was reduced in offspring of treated mice, males having significantly reduced weights at 3--4 weeks. When weaned at 21 days, treated offspring were given 10% alcohol to drink. Intake amounted to 31 mg/g body weight each day on average. Ethological analysis of behaviour occurring in encounters between alcohol-treated and control mice of the same sex showed that exploration and scanning were increased in duration in treated mice of both sexes and were increased in frequency in treated females. The frequency of self-grooming was reduced in treated mice of both sexes and scratching in treated males. Ethyl alcohol (10%) as drinking fluid for 5 days to 21 day old mice procuced different behavioural effects. In treated males the social elements, 'investigate', 'sniff' and 'follow' were increased in frequency during encounters and 'digging' was reduced. Treated females showed no change in social behaviour. Weight gain was reduced in treated males.