Early handling can attenuate adverse effects of fetal ethanol exposure

Neonatal choline supplementation ameliorates the effects of prenatal alcohol exposure on a discrimination learning task in rats

Prenatal alcohol exposure can disrupt brain development and lead to a myriad of behavioral alterations, including motor coordination deficits, hyperactivity, and learning deficits. There remains a need, however, to identify treatments and interventions for reducing the severity of alcohol-related neurodevelopmental disorders. Some of the alcohol-induced deficits in learning may be related to alterations in cholinergic functioning. Interestingly, there is a growing literature demonstrating that pre- and/or early postnatal choline supplementation can lead to long-term enhancement in learning and memory and cholinergic activity in rats. The present study examined whether such early choline supplementation might counter the effects of prenatal alcohol treatment on a visuospatial discrimination task. Pregnant Sprague-Dawley rats were randomly assigned to one of three prenatal treatment groups. One group received a liquid diet containing 35% ethanol-derived calories (EDC) from gestational day (GD) 6-20. A second group served as a pair-fed (PF) control group and the third group served as an ad lib lab chow (LC) control. On postnatal day (PD) 2, pups were assigned within-litter to one of three postnatal treatments: choline, saline vehicle, or no treatment. Choline and vehicle pups were intubated with a choline chloride solution or vehicle daily from PD 2 to 21, whereas the non-treated pups were handled daily but not intubated. On PD 45, subjects were tested on a visuospatial discrimination task. Ethanol-exposed subjects who were not treated neonatally with choline committed a significantly greater number of errors both during acquisition and during delayed discrimination training compared to both PF and LC controls. Neonatal choline treatment significantly improved performance on the discrimination task in all groups; however, the beneficial effects of choline were significantly larger in ethanol-exposed subjects. Indeed, the performance of ethanol-exposed pups treated with neonatal choline did not differ from any of the PF or LC groups on any measure. Thus, early postnatal choline supplementation significantly attenuated the effects of prenatal alcohol on this learning task. Importantly, these effects were not due to the acute effects of choline, but rather to long-term changes in brain and behavioral development. These data suggest that early dietary interventions may reduce the severity of fetal alcohol effects.

Therapeutic motor training ameliorates cerebellar effects of postnatal binge alcohol

We have used training on complex motor tasks to ameliorate effect of neonatal alcohol exposure. On postnatal days 4-9, alcohol-exposed (AE) rats were given 4.5 g/kg/day of alcohol by artificial rearing; gastrostomy control (GC) rats were given an isocaloric mixture of maltose/dextrin; suckling control (SC) rats were suckled normally. At 6 months of age, animals from the three groups underwent either rehabilitation training on a series of complex motor tasks, motor conditioning on a flat runway, or an inactive home cage condition. Subsequently, animals were either tested on three tests of balance and coordination, or were used for cerebellar morphology. After rehabilitation, but not after motor conditioning, male and female AE rats exhibited significant improvement in independent tests of motor skills. Using unbiased stereological morphological techniques, rehabilitated SC and AE animals were found to exhibit significantly more parallel fiber synapses per Purkinje cell in the paramedian lobule.

Amelioration of fetal alcohol-related neurodevelopmental disorders in rats: exploring pharmacological and environmental treatments

Fetal alcohol syndrome (FAS) and alcohol-related neurodevelopmental disorders (ARNDs) in children are characterized by life-long compromises in learning, memory, and adaptive responses. Until the advent of effective prevention measures, it will remain necessary to seek ways to treat the life-long neurobehavioral consequences of prenatal alcohol exposure. To date, there are no clinical remedies to recommend for either specific or global fetal alcohol effects. This article reviews our basic research in animal models that assesses the potential of global environmental manipulations or specific psychopharmacological treatments to ameliorate the neurobehavioral effects of prenatal exposure to alcohol. Postweaning environmental enrichment can improve behavioral performance and ameliorate or even eliminate deficits in prenatal alcohol-exposed rats, although there is persistent impairment in neuronal plasticity, as indicated by the failure of hippocampal pyramidal cells to increase dendrite spine density. Behavioral and neural responses to CNS stimulants differ in rats exposed prenatally to alcohol, although it is not clear that these shifts in dose-response curves would predict benefit to children. Although the present results may sound a note of optimism for the development of effective treatment strategies for children with FAS or ARNDs, it is important to consider that application of these findings in rodents may not be straightforward. We also need to know the critical features of specific environments that influence brain development, and the limits of pharmacotherapy, as well as critical periods of exposure. Continued study of the beneficial, ameliorative effects of environmental enrichment, rehabilitative training, and of pharmacological therapies in animal models, will remain a valuable source of information for eventually devising treatments specific for children with FAS and ARNDs.

Preweaning experience as a modifier of prenatal drug effects in rats and mice--a review

The effects of preweaning experience in rats and mice on neuroendocrine and behavioral end points and their implications for prenatal drug effects are reviewed. The hypothalamo-pituitary-adrenal axis and the dopaminergic system were shown to be affected. Behavior related to hippocampal, adrenocortical functions and to the benzodiazepine receptor system was also modified. Other paradigms (nociception, conditioned taste aversion) exhibited susceptibility to such preweaning manipulations also. The effects of these early experiences seem to be mediated through complex factors including neuroendocrine responses of the pup to hypothermia and a permanent alteration of mother-infant interactions, with subsequent effects on neuroendocrine functions that are important for postnatal brain organization. Studies of interactions between prenatal drug effects and preweaning manipulations have been performed only with ethanol. When extending this work to other compounds, the systems and functions described above may provide some guidance in looking for possible interactions. In most cases the preweaning manipulations alleviated the effects of prenatal ethanol exposure. These findings may have important implications regarding the controversy about environmental influences affecting the outcome of exposure to neurobehavioral teratogens.

Chronic intermittent stress does not differentially alter brain corticosteroid receptor densities in rats prenatally exposed to ethanol

Prenatal ethanol exposure produces hypothalamic-pituitary-adrenal (HPA) hyperresponsiveness to stressors. The present study tested the hypothesis that decreased corticosteroid receptor densities at HPA feedback sites may play a role in deficient feedback inhibition and the resultant HPA hyperresponsiveness that is observed following prenatal ethanol exposure. Brains of adult Sprague-Dawley rats from prenatal ethanol (E), pair-fed (PF) and ad libitum-fed control (C) treatment groups were examined for both mineralocorticoid receptor (MR; Type I) and glucocorticoid receptor (GR; Type II) densities using a cytosolic binding assay. Experiment 1 compared the effects of chronic intermittent stress (Stress Regimen I) and corticosterone (CORT) pellet implants on hippocampal corticosteroid receptor densities in control rats. Experiment 2 determined whether exposure to Stress Regimen I would differentially downregulate and whether adrenalectomy (ADX) would differentially upregulate hippocampal corticosteroid receptors in E compared with PF and C animals. Experiment 3 examined the effects of a modified chronic intermittent stress regimen (Stress Regimen II) on corticosteroid receptor densities at several HPA feedback sites (hippocampus, prefrontal cortex, hypothalamus, and anterior pituitary) in E compared with PF and C animals. CORT pellet implants significantly downregulated hippocampal GR and MR densities in control males and females. Exposure to Stress Regimen I produced downregulation of hippocampal GRs and MRs in males comparable with that produced with CORT pellet implants, and significant downregulation of hippocampal GRs in females across all prenatal treatment groups. This stress regimen also elevated basal plasma CORT levels without concurrent changes in plasma CBG levels, and increased relative adrenal weights in both males and females. In addition, upregulation of hippocampal GRs occurred at 7 days compared with 24 h following ADX in females that had previously been exposed to this stress regimen. Following exposure to Stress Regimen II, both the downregulation of hippocampal corticosteroid receptors and the increase in basal CORT levels in males and females appear to have been abolished by the changes in housing condition during the period of chronic stress. Importantly, prenatal ethanol exposure did not differentially alter GR or MR densities at any feedback site under non-stressed conditions. Exposure to Stress Regimen II, revealed subtle effects of prenatal treatments on hippocampal GRs however it is unlikely that these changes in corticosteroid receptor densities mediated the feedback inhibition deficits observed in E animals. Together, these data demonstrate that: (1) a relatively mild intermittent stress regimen can increase basal CORT levels and downregulate hippocampal corticosteroid receptor densities (2) a seemingly small change in housing conditions during stress appears to eliminate both receptor downregulation and increase in basal CORT levels and (3) decreased corticosteroid receptor densities at HPA feedback sites in the brain do not appear to underlie the HPA hyperresponsiveness observed in E animals.

Infantile handling eliminates reversal learning deficit in rats prenatally exposed to alcohol

Prenatal exposure to ethanol results in learning deficits and alters physiological response to stress. Neonatal handling and stimulation. on the other hand, produce long-lasting physiological and behavioral changes in response to stress. To determine whether early handling, consisting of daily separation and tactile stimulation for the first 3 weeks, can modify fetal alcohol effects on learning ability of young adult rats, offspring of rats chronically exposed to ethanol throughout pregnancy and control animals were trained in a T-maze to learn a position response and then to reverse the learned response. The nonhandled, ethanol-treated rats were deficient on reversal, but the ethanol-treated rats that were handled during the first 3 weeks of postnatal development showed no deficit in learning to reverse their previously learned responses. Postnatal handling had no effect on acquisition in alcohol-treated rats. Neither reversal nor acquisition was affected by infantile handling in pair-fed or normal control animals. Early handling may have eliminated the reversal deficit in the ethanol-treated offspring by altering their physiological and behavioral reactivity to stress.

Therapeutic effects of complex motor training on motor performance deficits induced by neonatal binge-like alcohol exposure in rats . I. Behavioral results

The effects of complex motor task learning on subsequent motor performance of adult rats exposed to alcohol on postnatal days 4 through 9 were studied. Male and female Long-Evans rats were assigned to one of three treatments: (1) alcohol exposure (AE) via artificial rearing to 4.5.g kg-1 day-1 of ethanol in a binge-like manner (two consecutive feedings), (2) gastrostomy control (GC) fed isocaloric milk formula via artificial rearing, and (3) suckling control (SC), where pups remained with lactating dams. After completion of the treatments, the pups were fostered back to lactating dams, and after weaning they were raised in standard cages (two-three animals per cage) until they were 6 months old. Rats from each of the postnatal treatments then spent 20 days in one of three conditions: (1) inactive condition (IC), (2) motor control condition (MC) (running on a flat oval track), or (3) rehabilitation condition (RC) (learning to traverse a set of 10 elevated obstacles). After that all the animals were tested on three tasks, sensitive to balance and coordination deficits (parallel bars, rope climbing and traversing a rotating rod). On parallel bars, both male and female rats demonstrated the same pattern of outcomes: AE-IC rats made significantly more mistakes (slips and falls) than IC rats from both control groups. After 20 days of training in the RC condition, there were no differences between AE and both SC and GC animals in their ability to perform on the parallel bars test. On rope climbing, female animals showed a similar pattern of abilities: AE-IC rats were the worst group; exercising did not significantly improve the AE rats' ability to climb, whereas the RC groups (SC, GC and AE) all performed near asymptote and there were no significant differences among three neonatal treatment groups. There was a substantial effect of the male rats' heavier body weight on climbing ability, and this may have prevented the deficits in AE rats behavior from being detected. Nevertheless, male animals from all three postnatal treatments (SC, GC and AE) were significantly better on this task after RC. Female and male rats from all three postnatal groups demonstrated significantly better performance on the rotarod task after 20 days of 'rehabilitation'. These results suggest that complex motor skill learning improves some of the motor performance deficits produced by postnatal exposure to alcohol and can potentially serve as a model for rehabilitative intervention.

Prenatal alcohol exposure results in hyperactivity of the hypothalamic-pituitary-adrenal axis of the offspring: modulation by fostering at birth and postnatal handling

Exposure of fetal rats to alcohol results in permanent hyperactivity of the hypothalamic-pituitary-adrenal (HPA) axis. In contrast, postnatal handling or fostering have been reported to restrain HPA activity. Because of the deleterious consequences of a hyperresponsive HPA axis, we thought that the possibility that postnatal manipulations might be able to reverse the influence of prenatal alcohol treatment deserved investigation. To test this hypothesis, we exposed rat dams to alcohol by inhalation during the second week of gestation. At birth, pups were either fostered or remained with their dam. For the first 3 weeks, litters were handled daily for 15 min or left undisturbed. At 22 days of age, male and female pups were decapitated under basal conditions, after 10 min of mild electro-footshock, or 10 min after footshock had been terminated. As expected, prenatal exposure to alcohol induced increased adrenocorticotropin (ACTH) secretion in response to footshock, and postnatal handling of control pups resulted in a suppression of corticosterone and ACTH release, although changes in this latter hormone did not reach statistical significance. Surprisingly, however, pups exposed to alcohol that were also fostered and handled after birth, showed an ACTH response to footshock stress that was significantly larger than all other groups. This unexpected response may be due to alterations in maternal-pup behaviors and may indicate that these manipulations act on different neuronal substrates within the central HPA of young rats. Further studies are needed to determine whether adrenal regulation is also altered in animals exposed to alcohol prenatally and reared in a similar manner.

Effects of prenatal ethanol exposure and early experience on radial maze performance and conditioned taste aversion in mice

C57BL/6 mice were intubated on gestational days 14-18 twice daily with 1.58 g/kg ethanol, 4.2 g/kg sucrose, or remained untreated. Offspring of ethanol-treated or lab chow control groups were raised either by group-housed dams and weaned on postnatal day (PND) 28 (enriched condition), or by individually housed dams and weaned on PND 21 (standard condition). Offspring of the sucrose control group were raised by individually housed dams and weaned on PND 21. Groups did not differ in pup weight or litter size. Male and female offspring were assessed for performance in an unbaited radial maze (PND 45-52) and male offspring only were tested for conditioned taste aversion (PND 54-59). As hypothesized, mice prenatally exposed to ethanol and raised under standard conditions failed to develop the conditioned taste aversion response. In contrast, subjects with in utero ethanol exposure that were raised under enriched preweaning conditions developed the taste aversion response. Maze performance improved significantly over days, but no significant effects were detected for either prenatal treatment or preweaning rearing conditions. In conclusion, enriched preweaning rearing conditions abolished the detrimental effects of prenatal ethanol exposure on conditioned taste aversion, but radial maze performance remained unaffected by any treatment in this study.

Prenatal alcohol exposure and the effects of environmental enrichment on hippocampal dendritic spine density

The effects of environmental enrichment on synaptic spine density in hippocampal area CAI were examined in rats exposed prenatally to alcohol. Pregnant dams were given ethanol via intragastric intubation (6 g/kg/day) from gestational days 8 through 19, or given isocaloric sucrose. An untreated control group was also used. After weaning, offspring from the three groups were then reared for 10 weeks in either isolated (caged alone, not handled) or enriched (group housed with "toys," handled) conditions. Animals were then sacrificed, the brains Golgi impregnated, and CAI pyramidal cell apical and basilar spine densities quantified. Among isolated animals there were no significant differences between control and alcohol-exposed groups. In general, environmental enrichment increased apical or basilar spine densities in untreated and sucrose controls. However, in prenatal alcohol-exposed animals, environmental enrichment did not increase spine densities. Because the environmental enrichment acted postnatally, these findings suggest that the effects of prenatal alcohol exposure included decreased neural plasticity enduring into early adulthood. Such a reduction in neuroanatomical plasticity in hippocampus may be associated with cognitive impairments found following prenatal alcohol exposure.