Effects of ethyl alcohol on behaviour in nursing female mice

Mothering under the influence: how perinatal drugs of abuse alter the mother-infant interaction

Although drug-abusing women try to moderate their drug and alcohol use during pregnancy, they often relapse at a time when childcare needs are high and maternal bonding is critical to an infant's development. In the clinical setting, the search for the neural basis of drug-induced caregiving deficits is complex due to several intervening variables. Rather, the preclinical studies that control for drug dose and regimen, as well as for gestational and postpartum environment, allow a precise determination of the effects of drugs on maternal behaviour. Given the relevance of the issue, this review will gather reports on the phenotypic correlates of maternal behaviour in preclinical studies, and focus on the detrimental consequences on the mother-infant interaction exerted by the perinatal use of alcohol, nicotine, cannabis, cocaine and stimulants and opiates. The drug-induced disruptions of this maternal repertoire are associated with adverse maternal and infant outcomes. A comprehensive overview will help promote the refinement of the treatment approaches toward maternal drug use disorders and maternal misbehaviour, in favour of augmented parenting resiliency.

Continuous and Intermittent Alcohol Free-Choice from Pre-gestational Time to Lactation: Focus on Drinking Trajectories and Maternal Behavior

BACKGROUND

Alcohol consumption during pregnancy and lactation induces detrimental consequences, that are not limited to the direct in utero effects of the drug on fetuses, but extend to maternal care. However, the occurrence and severity of alcohol toxicity are related to the drinking pattern and the time of exposure. The present study investigated in female rats long-term alcohol drinking trajectories, by a continuous and intermittent free-choice paradigm, during pre-gestational time, pregnancy, and lactation; moreover, the consequences of long-term alcohol consumption on the response to natural reward and maternal behavior were evaluated.

METHODS

Virgin female rats were exposed to home-cage two-bottle continuous- or intermittent "alcohol (20% v/v) vs. water" choice regimen along 12 weeks and throughout pregnancy and lactation. Animals were tested for saccharin preference, and maternal behavior was assessed by recording dams' undisturbed spontaneous home-cage behavior in the presence of their offspring.

RESULTS

Our results show that the intermittent alcohol drinking-pattern induced an escalation in alcohol intake during pre-gestational time and lactation more than the continuous access, while a reduction in alcohol consumption was observed during pregnancy, contrarily to the drinking trajectories of the continuous access-exposed rats. Long-term voluntary alcohol intake induced a decreased saccharin preference in virgin female rats and a significant reduction in maternal care, with respect to control dams, although the intermittent drinking produced a greater impairment than the continuous-access paradigm.

CONCLUSION

The present data indicate that both alcohol-drinking patterns are associated to modifications in the drinking trajectories of female rats, in pre-gestational time, during pregnancy and lactation. Moreover, long-lasting alcohol intake can affect sensitivity to natural rewarding stimuli and maternal behavior and sensitivity to natural rewarding stimuli in a pattern-related manner. This study underlies the importance of modeling human alcohol habit and its consequences on the mother-infant dyad, in order to prevent detrimental effects on offspring development and maturation.

Alcohol and pregnancy: Effects on maternal care, HPA axis function, and hippocampal neurogenesis in adult females

Chronic alcohol consumption negatively affects health, and has additional consequences if consumption occurs during pregnancy as prenatal alcohol exposure adversely affects offspring development. While much is known on the effects of prenatal alcohol exposure in offspring less is known about effects of alcohol in dams. Here, we examine whether chronic alcohol consumption during gestation alters maternal behavior, hippocampal neurogenesis and HPA axis activity in late postpartum female rats compared with nulliparous rats. Rats were assigned to alcohol, pair-fed or ad libitum control treatment groups for 21 days (for pregnant rats, this occurred gestation days 1-21). Maternal behavior was assessed throughout the postpartum period. Twenty-one days after alcohol exposure, we assessed doublecortin (DCX) (an endogenous protein expressed in immature neurons) expression in the dorsal and ventral hippocampus and HPA axis activity. Alcohol consumption during pregnancy reduced nursing and increased self-directed and negative behaviors, but spared licking and grooming behavior. Alcohol consumption increased corticosterone and adrenal mass only in nulliparous females. Surprisingly, alcohol consumption did not alter DCX-expressing cell density. However, postpartum females had fewer DCX-expressing cells (and of these cells more immature proliferating cells but fewer postmitotic cells) than nulliparous females. Collectively, these data suggest that alcohol consumption during pregnancy disrupts maternal care without affecting HPA function or neurogenesis in dams. Conversely, alcohol altered HPA function in nulliparous females only, suggesting that reproductive experience buffers the long-term effects of alcohol on the HPA axis.

Diurnal levels of Fos immunoreactivity are elevated within hypocretin neurons in lactating mice

The hypocretins modulate arousal via actions across multiple terminal fields. Thus, alterations in hypocretin neurotransmission may contribute to altered sleep patterns observed during lactation. This study examined whether lactation is associated with alterations in the number of hypocretin neurons and in diurnal Fos-immunoreactivity within hypocretin neurons in female mice. Alterations in Fos-immunoreactivity were also examined within two hypocretin terminal regions; the medial preoptic area and the locus coeruleus. Fos-immunoreactivity was increased within hypocretin neurons and the medial preoptic area in lactating females. No differences were observed in the number of hypocretin neurons or in Fos-immunoreactivity within the locus coeruleus.

Sodium valproate: effects on maternal behaviour in the mouse

The behaviour of lactating mice in their home cages was examined by ethological procedures at 1, 7, 14 and 21 days postpartum. Early in lactation, maternal behaviour was more frequent in the light phase of the 24 hr cycle, whereas non-social activity occupied a greater amount of time during the dark phase. As the pups became older, maternal behaviour declined, and at 21 days the dams showed a marked increase of solitary immobility. Behavioural alterations produced by the administration of sodium valproate at 600 mg/l as drinking fluid during pregnancy and lactation (group SVP), and during lactation only, (group PN) were assessed. (Intake of drug amounted to 153 mg/kg during gestation and 186 mg/kg in lactation). Dams of group PN showed behavioural differences from controls in late lactation, pup nursing being prolonged at day 14 postpartum and the frequency of all categories of active behaviour, other than nursing and nestbuilding, was increased at day 21 postpartum in the dark phase of their daily cycle. There was not significant effect on categories of behaviour in dams of the SVP group. Overall, sodium valproate, at this dose, did not reduce maternal care.

Social models of drinking behavior in animals. The importance of individual differences

Although certain social environments clearly facilitate alcohol intake in humans, the role of social factors in alcohol consumption by animals is less clear. While social housing conditions such as crowding and isolation increase alcohol consumption in animals, in both cases this is mediated by heightened stress. Increases in social tension increase alcohol consumption in social groups of animals, but the literature is extremely variable in reports of how dominance correlates with alcohol consumption. Alcohol administration has biphasic effects on social behavior of animals similar to its biphasic effects on activity levels. We report a novel, social animal model of alcoholism. Rats raised over prolonged periods in highly enriched, social colony environments develop a variety of rhythms of alcohol consumption. But in each colony, only a few animals develop into extreme overconsumers of alcohol, and the proportion of colony-housed animals that develop such excessive alcohol -consumption habits is similar to the proportion of humans with alcohol problems. These overconsumers of alcohol from a rat colony show a variety of alterations in behavior, including chronic inactivity and low dominance standing. They represent a novel, voluntary animal model of social alcoholism.

The effects of alcohol induced malnutrition in pregnancy on offspring brain and behavioral development

Alcohol is known to have various deleterious effects in all animals including man. The present study was designed to establish whether the effects of moderate EtOH intake during pregnancy on offspring are due to toxic effects of the substance or to nutritional changes; whether effects are long lasting or limited in duration; and whether effects are due to the prenatal action of the substance or effects persisting into the postnatal period. The findings show that the effects obtained in our study are due to malnutrition engendered in the prenatal period and are of limited duration. Since much evidence suggests that early deficits are difficult to compensate for, it is possible that the tests used with mature animals in this study may have been insensitive to residual deficits. Alternatively, rats may truly have compensated for early retardation. This does not necessarily imply that the same compensatory processes would apply in humans, where greater complexity of environmental demands is imposed from an early age.

Behavioral effects of phenobarbitone II. Effects in nursing female mice

Phenobarbitone supplied at concentrations of 187.5 mg/l and 500 mg/l (50--60 mg/kg and 120--190 mg/kg daily) in the drinking fluid of mice throughout pregnancy and lactation did not affect gestation period, numbers born or resorbed or pup weights at birth and weaning. The higher dose caused significant retardation in eye-opening, development of forelimb extension, negative geotaxis, in appearance of washing and self-grooming behaviours and in cessation of suckling. The lower dose had no detectable effects. Ethological methods were used to examine spontaneous behaviour of nursing dams within home cages on days 1, 7, 14 and 21 postpartum. Treated dams showed differences in behaviour from controls, the most marked of which were increased levels of Maternal Behaviour and decreases in Non-Social Activity in the high-dose group at day 1, and continuance of pup Nursing in both treated groups and Nest Building in the high-dose group at day 21 when controls were ceasing these behaviours. At 21 days all treated dams also showed less Immobility than controls and high-dose dams a smaller amount of pup Social Investigation. Many behavioural differences at 21 days were related to developmental delay of treated pups. Overall, phenobarbitone did not impair maternal care.