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

Dietary choline levels modify the effects of prenatal alcohol exposure in rats

Prenatal alcohol exposure can cause a range of physical and behavioral alterations; however, the outcome among children exposed to alcohol during pregnancy varies widely. Some of this variation may be due to nutritional factors. Indeed, higher rates of fetal alcohol spectrum disorders (FASD) are observed in countries where malnutrition is prevalent. Epidemiological studies have shown that many pregnant women throughout the world may not be consuming adequate levels of choline, an essential nutrient critical for brain development, and a methyl donor. In this study, we examined the influence of dietary choline deficiency on the severity of fetal alcohol effects. Pregnant Sprague-Dawley rats were randomly assigned to receive diets containing 40, 70, or 100% recommended choline levels. A group from each diet condition was exposed to ethanol (6.0g/kg/day) from gestational day 5 to 20 via intubation. Pair-fed and ad lib lab chow control groups were also included. Physical and behavioral development was measured in the offspring. Prenatal alcohol exposure delayed motor development, and 40% choline altered performance on the cliff avoidance task, independent of one another. However, the combination of low choline and prenatal alcohol produced the most severe impairments in development. Subjects exposed to ethanol and fed the 40% choline diet exhibited delayed eye openings, significantly fewer successes in hindlimb coordination, and were significantly overactive compared to all other groups. These data suggest that suboptimal intake of a single nutrient can exacerbate some of ethanol's teratogenic effects, a finding with important implications for the prevention of FASD.

Prenatal choline supplementation mitigates behavioral alterations associated with prenatal alcohol exposure in rats

BACKGROUND

Prenatal alcohol exposure can alter physical and behavioral development, leading to a range of fetal alcohol spectrum disorders. Despite warning labels, pregnant women continue to drink alcohol, creating a need to identify effective interventions to reduce the severity of alcohol's teratogenic effects. Choline is an essential nutrient that influences brain and behavioral development. Recent studies indicate that choline supplementation can reduce the teratogenic effects of developmental alcohol exposure. The present study examined whether choline supplementation during prenatal ethanol treatment could mitigate the adverse effects of ethanol on behavioral development.

METHODS

Pregnant Sprague-Dawley rats were intubated with 6 g/kg/day ethanol in a binge-like manner from gestational days 5-20; pair-fed and ad libitum chow controls were included. During treatment, subjects from each group were intubated with either 250 mg/kg/day choline chloride or vehicle. Spontaneous alternation, parallel bar motor coordination, Morris water maze, and spatial working memory were assessed in male and female offspring.

RESULTS

Subjects prenatally exposed to alcohol exhibited delayed development of spontaneous alternation behavior and deficits on the working memory version of the Morris water maze during adulthood, effects that were mitigated with prenatal choline supplementation. Neither alcohol nor choline influenced performance on the motor coordination task.

CONCLUSIONS

These data indicate that choline supplementation during prenatal alcohol exposure may reduce the severity of fetal alcohol effects, particularly on alterations in tasks that require behavioral flexibility. These findings have important implications for children of women who drink alcohol during pregnancy.

The plausibility of maternal nutritional status being a contributing factor to the risk for fetal alcohol spectrum disorders: the potential influence of zinc status as an example

There is increasing evidence that human pregnancy outcome can be significantly compromised by suboptimal maternal nutritional status. Poor diet results in a maternal-fetal environment in which the teratogenicity of other insults such as alcohol might be amplified. As an example, there is evidence that zinc (Zn) can interact with maternal alcohol exposure to influence the risk for fetal alcohol spectrum disorders (FASD). Studies with experimental animals have shown that the teratogenicity of alcohol is increased under conditions of Zn deficiency, whereas its teratogenicity is lessened when animals are given Zn-supplemented diets or Zn injections before the alcohol exposure. Alcohol can precipitate an acute-phase response, resulting in a subsequent increase in maternal liver metallothionein, which can sequester Zn and lead to decreased Zn transfer to the fetus. Importantly, the teratogenicity of acute alcohol exposure is reduced in metallothionein knockout mice, which can have improved Zn transfer to the conceptus relative to wild-type mice. Consistent with the above, Zn status has been reported to be low in alcoholic women at delivery. Preliminary data from two basic science and clinical nutritional studies that are ongoing as part of the international Collaborative Initiative on Fetal Alcohol Spectrum Disorders support the potential role of Zn, among other nutritional factors, relative to risk for FASD. Importantly, the nutrient levels being examined in these studies are relevant to general clinical populations and represent suboptimal levels rather than severe deficiencies. These data suggest that moderate deficiencies in single nutrients can act as permissive factors for FASD, and that adequate nutritional status or intervention through supplementation may provide protection from some of the adverse effects of prenatal alcohol exposure.

Prenatal choline supplementation mitigates the adverse effects of prenatal alcohol exposure on development in rats

Prenatal alcohol exposure can lead to a range of physical, neurological, and behavioral alterations referred to as fetal alcohol spectrum disorders (FASD). Variability in outcome observed among children with FASD is likely related to various pre- and postnatal factors, including nutritional variables. Choline is an essential nutrient that influences brain and behavioral development. Recent animal research indicates that prenatal choline supplementation leads to long-lasting cognitive enhancement, as well as changes in brain morphology, electrophysiology and neurochemistry. The present study examined whether choline supplementation during ethanol exposure effectively reduces fetal alcohol effects. Pregnant dams were exposed to 6.0g/kg/day ethanol via intubation from gestational days (GD) 5-20; pair-fed and lab chow controls were included. During treatment, subjects from each group received choline chloride (250mg/kg/day) or vehicle. Physical development and behavioral development (righting reflex, geotactic reflex, cliff avoidance, reflex suspension and hindlimb coordination) were examined. Subjects prenatally exposed to alcohol exhibited reduced birth weight and brain weight, delays in eye opening and incisor emergence, and alterations in the development of all behaviors. Choline supplementation significantly attenuated ethanol's effects on birth and brain weight, incisor emergence, and most behavioral measures. In fact, behavioral performance of ethanol-exposed subjects treated with choline did not differ from that of controls. Importantly, choline supplementation did not influence peak blood alcohol level or metabolism, indicating that choline's effects were not due to differential alcohol exposure. These data indicate early dietary supplements may reduce the severity of some fetal alcohol effects, findings with important implications for children of women who drink alcohol during pregnancy.

Alcohol exposure during the first two trimesters-equivalent alters the development of corpus callosum projection neurons in the rat

Children exposed prenatally to alcohol can display a variety of neural deficits, including an altered development of the corpus callosum (CC), the largest interhemispheric axon pathway in the brain. Furthermore, these children show functional abnormalities that are related to brain regions with significant numbers of CC connections. Little is known about how alcohol imparts influence on CC development, but one possible mechanism is by affecting the corpus callosum projection neurons (CCpn) directly. The purpose of this study was to quantify the effects of prenatal alcohol exposure on the number, size, and distribution of CCpn within the visual cortex. The visual cortex was selected specifically due to the many vision-related deficits noted in fetal alcohol exposed children and because the critical role of the CC in visual cortex development is well documented. Sprague-Dawley rat pups received one of four alcohol dosages during gestational days (G) 1-20, or reared as nutritional or untreated control animals. Each litter was categorized according to the peak blood alcohol concentration experienced. Pups were removed from each litter on days equivalent to G29, G36, G43, and G50, for histology and measurement. Callosal axons were labeled retrogradely to their CCpn using 1,1'-dioctadecyl-3,3,3',3'-tetramethylindocarbocyanine perchlorate (DiI) and the CCpn were then examined using confocal laser scanning microscopy. Differences between alcohol-exposed and control animals were observed in CCpn cell body size, number, and location with the cortex. This was particularly true of animals exposed to high doses of alcohol. In addition, some trends of CCpn development were found to be unchanged as a result of prenatal alcohol exposure. The results demonstrate clear differences in the development of CCpn in the visual cortex between alcohol-exposed and control animals and suggest that this development is particularly affected in those animals exposed to high doses of alcohol.

Maternal alcohol consumption increases sphingosine levels in the brains of progeny mice

The effect of 'binge' alcohol upon sphingolipid metabolism in the fetal alcohol syndrome (FAS) was examined in pregnant mice (C57BL/6J) by administering a single dose of alcohol during the third trimester (gestational day 15-16). The control mice were administered a sucrose solution of equal caloric value. Brains from progeny at postnatal days 5, 15, 21 and 30 were dissected into three regions, and sphingolipid concentrations of the brain regions were determined including assay of monoglycosylceramide, ceramide, sphingosine and sphingomyelin. We found that a single dose of ethanol induces an elevation of sphingosine (2-3.5-fold) in the brain of progeny. The level of brain ceramide at a dose of 1.5 g/kg was significantly higher than control. Alcohol consumption during pregnancy induces neuronal loss in progeny brains. Our result suggests that the elevation of sphingosine in progeny brain induced by maternal alcohol consumption may be responsible for observed neuronal loss in FAS.

Mouse inbred strain differences in ethanol drinking to intoxication

Recently, we described a simple procedure, Drinking in the Dark (DID), in which C57BL/6J mice self-administer ethanol to a blood ethanol concentration (BEC) above 1 mg/ml. The test consists of replacing the water with 20% ethanol in the home cage for 4 h early during the dark phase of the light/dark cycle. Three experiments were conducted to explore this high ethanol drinking model further. In experiment 1, a microanalysis of C57BL/6J behavior showed that the pattern of ethanol drinking was different from routine water intake. In experiment 2, drinking impaired performance of C57BL/6J on the accelerating rotarod and balance beam. In experiment 3, 12 inbred strains were screened to estimate genetic influences on DID and correlations with other traits. Large, reliable differences in intake and BEC were detected among the strains, with C57BL/6J showing the highest values. Strain means were positively correlated with intake and BEC in the standard (24 h) and a limited (4 h) two-bottle ethanol vs. water test, but BECs reached higher levels for DID. Strain mean correlations with other traits in the Mouse Phenome Project database supported previously reported genetic relationships of high ethanol drinking with low chronic ethanol withdrawal severity and low ethanol-conditioned taste aversion. We extend these findings by showing that the correlation estimates remain relatively unchanged even after correcting for phylogenetic relatedness among the strains, thus relaxing the assumption that the strain means are statistically independent. We discuss applications of the model for finding genes that predispose pharmacologically significant drinking in mice.

Recombinant inbreeding in mice reveals thresholds in embryonic corpus callosum development

The inbred strains BALB/cWah1 and 129P1/ReJ both show incomplete penetrance for absent corpus callosum (CC); about 14% of adult mice have no CC at all. Their F(1) hybrid offspring are normal, which proves that the strains differ at two or more loci pertinent to absent CC. Twenty-three recombinant inbred lines were bred from the F(2) cross of BALB/c and 129, and several of these expressed a novel and severe phenotype after only three or four generations of inbreeding - total absence of the CC and severe reduction of the hippocampal commissure (HC) in every adult animal. As inbreeding progressed, intermediate sizes of the CC and the HC remained quite rare. This striking phenotypic distribution in adults arose from developmental thresholds in the embryo. CC axons normally cross to the opposite hemisphere via a tissue bridge in the septal region at midline, where the HC forms before CC axons arrive. The primary defect in callosal agenesis in the BALB/c and 129 strains is severe retardation of fusion of the hemispheres in the septal region, and failure to form a CC is secondary to this defect. The putative CC axons arrive at midline at the correct time and place in all groups, but in certain genotypes, the bridge is not yet present. The relative timing of axon growth and delay of the septal bridge create a narrow critical period for forming a normal brain.

Effect of prenatal alcohol exposure on midsagittal commissure size in rats

BACKGROUND

Fetal alcohol exposure in humans can cause a variety of brain and behavioral abnormalities. The brain abnormalities include defects in the corpus callosum that range from total absence (agenesis) to reduction in size or thickness. Determination of the critical alcohol level or time period of exposure to produce these effects is difficult because of the lack of control of possible mitigating factors.

METHODS

The present study was undertaken to examine possible relationships between midsagittal corpus callosum dimensions and prenatal alcohol level as measured by blood alcohol concentration, as well as prenatal period of exposure as measured by first- or second- or first- plus second-trimester equivalents in a rat model. In addition to the corpus callosum, the hippocampal and anterior commissures were also examined. Pregnant mothers were given a single daily dose of alcohol by intragastric gavage; four different doses were tested in different mothers. Peak blood alcohol concentration was determined at one of four hourly intervals thereafter. Control pregnant mothers were pairfed to individual alcohol treated mothers and handled accordingly, but no alcohol was given. Other controls consisted of normal, untreated pregnant mothers.

RESULTS

The results show all measures of corpus callosum and anterior commissure were not affected by any dose of alcohol during any time period. However, higher BAC levels during prolonged periods of alcohol exposure were associated with reduced size of the hippocampal commissure.

CONCLUSIONS

The results suggest that additional experimental factors not included in the present study are responsible for the effects observed in humans.

Effects of prenatal exposure to ethanol on callosal projection neurons in rat somatosensory cortex

The distribution and density of callosal projection neurons in the somatosensory cortex of mature rats was altered by prenatal exposure to ethanol. The density of callosal neurons was significantly greater in ethanol-treated rats than in controls. Ethanol exposure also altered the laminar distribution of callosal projection neurons. Whereas in control rats the cell bodies of callosal projection neurons were in layers II/III and V, in ethanol-treated rats most of these neurons were distributed in layers V and VI. Many of the ectopic neurons were generated toward the end of cortical neuronogenesis (i.e., on gestational day 20). This contrasts with controls wherein co-generated cohorts were distributed in layer II/III. Thus, the connectional phenotype of the callosal projection neurons is retained regardless of its laminar residence. These ethanol-induced abnormalities apparently result from defects in neuronal migration and axonal pruning.

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.

Effects of prenatal ethanol exposure and early experience on home-cage and open-field activity in mice

-C57BL/6 mice were intubated from gestational day 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 or by individually housed dams and weaned on PND 21. 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. Offspring were assessed for home-cage activity (PND 36-38) and open-field behavior (PND 40-42). Mice prenatally exposed to ethanol showed increased activity in their home cages, whereas open-field behavior was generally not different from that of control groups. Conversely, different preweaning rearing conditions had affected open-field behavior, but not home-cage activity. In conclusion, home-cage behavior was a sensitive paradigm for detecting hyperactivity subsequent to a relatively low dose of prenatal ethanol in mice, and communal nesting/late weaning vs. individual nesting/ standard weaning may be a useful preweaning environmental manipulation to study possible modifications of prenatal neurobehavioral effects.

Sex differences in corpus callosum: influence of prenatal alcohol exposure and maternal undernutrition

The functional significance of sex differences in the size of the corpus callosum was investigated using a prenatal alcohol exposure paradigm that influences the fetal hormonal milieu. Adult male and female Long-Evans rats were selected from one of 3 prenatal treatment histories: prenatal alcohol-exposed (35% ethanol-derived calories), nutritional control (0% ethanol-derived calories) or standard control (lab chow). Subjects were assessed for open field activity at 85 days of age. At 100 days of age, midline sagittal areas of the corpus callosum and the anterior commissure were determined for these subjects. Male control subjects had significantly larger callosal areas than female controls. Prenatal alcohol exposure significantly decreased the total callosal area, and abolished this sexual dimorphism. When the callosal measurements were analyzed using Denenberg's regions, differential effects of prenatal alcohol exposure, undernutrition and sex were dissociable by subarea. There were no significant sex differences or effects of prenatal alcohol exposure in the midline sagittal area of the anterior commissure. Callosal size was negatively correlated to open field activity, suggesting a possible role in normal exploratory behavior and to the overactivity observed after prenatal alcohol exposure.

Genetic and developmental defects of the mouse corpus callosum

Among adult BALB mice fewer than 20% usually have a small or absent corpus callosum (CC) and inheritance is polygenic. In the fetus at the time when the CC normally forms, however, almost all BALB mice show a distinct bulge in the interhemispheric fissure and grossly retarded commissure formation, and inheritance appears to result from two autosomal loci, provided the overall maturity of fetuses is equated. Most fetuses recover from the early defect when the CC axons manage to cross over the hippocampal commissure, and thus there is developmental compensation for a genetic defect rather than arrested midline development. The pattern of interhemispheric connections when the adult CC is very small is topographically normal in most respects, despite the unusual paths of the axons. The proportion of mice which fail to recover completely can be doubled by certain features of the maternal environment, and the severity of defects in adults can also be exacerbated by new genetic mutations which create new BALB substrains. The behavioral consequences of absent CC in mice are not known, nor have electrophysiological patterns been examined. The mouse provides an important model for prenatal ontogeny and cortical organization in human CC agenesis, because these data are not readily available for the human condition.

Ultrastructure of neurons of the sensorimotor cortex in progeny of rats receiving alcohol during pregnancy

We have studied the dynamics of ultrastructural changes in the neurons of the sensorimotor cortex on days 21, 30, and 60 of life in offspring of rats given 20% alcohol (2 g/kg) during pregnancy. Moderate antenatal alcoholization leads to certain disturbances in the ultrastructure of the cortical neurons and their dendrites. This is manifested as the presence of signs of retardation in the maturation of nervous cell populations as dystrophic changes in the neurons and their dendrites, and as display of the repair character with their own dynamics in the postnatal period of ontogenesis. The first two categories of the ultrastructural changes in the cortical neurons become more manifest at early stages of postnatal development of the offspring, and the repair processes at the age of two months. Despite the presence of the repair shifts, the dystrophic changes in the neurons of a hypoxic nature are present up to the period of sexual maturation. This shows that the antenatal alcoholic intoxication in the offspring is manifested in postnatal ontogenesis for a long period.

Commissural size in neonatal rats: effects of sex and prenatal alcohol exposure

Sex differences have been reported in the size of the adult corpus callosum in both humans and rodents. This experiment investigated whether sex and/or different prenatal treatment conditions would influence commissural size at birth. Male and female 3-day-old Long Evans rats were selected from one of three prenatal treatment histories: prenatal alcohol-exposed (35% ethanol-derived calories, 35% EDC), nutritional control (0% ethanol-derived calories, 0% EDC) or standard control (lab chow). Midline sagittal areas of the corpus callosum and the anterior commissure were determined for these subjects. Male control subjects had significantly larger callosal areas than females. Prenatal alcohol exposure significantly abolished this sexual dimorphism, with 35% EDC males having a significantly smaller callosal area than males from both control groups. This effect was independent of prenatal treatment differences in body or brain size. There were no significant sex differences in the midline sagittal area of the anterior commissure, nor were there any apparent effects of prenatal treatment on this measure. These results indicate that sex differences in the size of the corpus callosum are present at birth. Since a difference in myelination cannot account for this difference in area, there may be a sex difference in the number of fibers or in the average fiber size. Additionally, the effects of prenatal alcohol exposure on male, but not female, offspring suggest that this alcohol-related birth defect is hormonally mediated.

Synaptogenesis in the hippocampal dentate gyrus: effects of in utero ethanol exposure

In animal models of Fetal Alcohol Syndrome, ethanol causes a number of changes in brain development, with many of these changes being very transient. This is especially true for the process of synaptogenesis in different brain areas. Our quantitative electron microscopic study of synaptogenesis in the molecular layer of the rat dentate gyrus supports the above statement, by demonstrating that ethanol has no effect on the appearance of synapses in the dentate gyrus during early postnatal life (10-30 days old). However, prenatal ethanol exposure does appear to affect the process of synapse turnover, which is indicated by the significantly delayed appearance of complex (curved) synapses and multiple synaptic contacts on single axonal terminals. Efficient synapse turnover is thought to be required for the normal maintenance of neuronal plasticity, which in turn ensures an animal's ability to respond to novel environments, tasks and injuries. It would seem that the prenatal neurotoxicology of ethanol may manifest itself by more subtle mechanisms at sites of structural and functional importance.

Microencephaly and hyperactivity in adult rats can be induced by neonatal exposure to high blood alcohol concentrations

To investigate whether or not blood alcohol concentration during the brain growth spurt has an influence on the permanency of alcohol-induced central nervous system damage, an artificial rearing technique was used to administer a daily dose of alcohol (6.6 g/kg/day) to neonatal rats during postnatal days 4 to 10. The alcohol was administered either in a condensed pattern over 8 h resulting in cyclic blood alcohol concentrations with high peaks, or uniformly over each 24-h period resulting in stable, but low peaks. The condensed alcohol exposure resulted in considerable microencephaly (20% to 25%), with significant growth deficits in the cerebrum, cerebellum, and brain stem of rats of either sex at day 10; there still was significant microencephaly (16% to 19%) in adult rats that received the condensed alcohol exposure as neonates. Furthermore, activity at day 90 in rats of either sex that had condensed alcohol exposure was elevated compared with that of the gastrostomy control group. In contrast, the rats having uniform alcohol exposure had only nonsignificant changes in brain weight both on day 10 and day 90 and did not exhibit hyperactivity at day 90. Thus, neonatal alcohol exposure producing high blood alcohol concentrations caused permanent deficits in brain growth and significant changes in activity, whereas the same daily dose of alcohol administered in a pattern that resulted in consistently low blood alcohol concentrations failed to produce either permanent microencephaly or increased activity. These data support the hypothesis that patterns of alcohol exposure that produce high concentrations in the blood, such as "binge-drinking," increase the risk of permanent damage to the developing brain.

Heredity and alcohol-induced brain anomalies: effects of alcohol on anomalous prenatal development of the corpus callosum and anterior commissure in BALB/c and C57BL/6 mice

Using two inbred strains of mice which have similar rates of alcohol metabolism, we asked whether prenatal alcohol exposure would cause greater incidence and severity of defects in the development of two forebrain fiber tracts, the corpus callosum and the anterior commissure, in mice prone to these defects (BALB/c) than in mice not prone to these defects (C57BL/6). Pregnant animals were fed 0.6 kcal/g body weight of a Sustacal-based liquid diet containing 0, 15, 17.5, 20, or 25% ethanol-derived calories from day 7 to fetal assessment on day 18 of gestation. Most of alcohol's greatest effects and the greatest strain differences in alcohol's effects on fetal variables were produced by the 17.5% diet. This dose had inhibitory effects on fetal body, brain, and midsagittal corpus callosum and anterior commissure growth. All these effects, except that on brain weight, were significantly greater in C57s than in BALBs. When the results were compared with prenatal growth curves for normal untreated mice, the effect of alcohol on corpus callosum but not anterior commissure growth was largely explained by its effects on overall development. The 17.5% diet had a greater specific effect on size of the anterior commissure in C57s than BALBs but increased the incidence and severity of its permanent dysmorphology in BALBs more than in C57s. Anterior commissure size and morphology may be sensitive indicators of alcohol's effects on prenatal brain development. Hereditary differences in rate of maternal alcohol metabolism no doubt have important consequences for risks arising from prenatal alcohol exposure. However, this study clearly indicates that inherited factors, other than those that influence rate of alcohol metabolism, are important influences on the overall fetal response and the specific responses of the anterior commissure to prenatal alcohol exposure.

Differential deficits in regional brain growth induced by postnatal alcohol

Neonatal rats were exposed to alcohol during a period of brain development equivalent to part of the human third trimester. Rat pups were fed a milk formula containing either alcohol (9.8 g/kg/day) or isocaloric maltose/dextrin using artificial rearing techniques from postnatal days 4-10. Blood alcohol concentrations reached 345.8 +/- 15.6 mg/dl on postnatal day 6. All animals, including a group of normally reared suckle controls, were sacrificed on postnatal day 10, and the brains were perfused and processed for the Timm histochemical technique. Significant microencephaly (30% reduction in brain growth) was found in the alcohol-exposed animals. Growth deficits also were found in specific brain regions of the alcohol-exposed rats. The overall area of the hippocampus proper at a midtemporal level was reduced by 26.1% compared to controls. Sublaminae within the hippocampus were stunted as much as 40.5%. An overall reduction of 14.5% was found in the midsagittal (vermal) cerebellum. In contrast, growth of the dentate gyrus appeared much less affected (6.8% deficit) by the alcohol exposure. These data indicate that not all regions of the brain are affected equally by alcohol exposure during the third trimester equivalent.

Combined effects of moderate ethanol consumption and a low-protein diet during gestation on brain development in BALB/c mice

We investigated whether or not moderate ethanol consumption during gestation would interact with the effects of a low-protein diet in affecting brain development in BALB/c mice. The independent variables included fetal body and brain weights and cross-sectional area in midsagittal sections of the corpus callosum (CC) and anterior commissure (CA). Pregnant animals were fed either ethanol 12% v/v or an isocaloric sucrose solution from days 5 to 19 of gestation, when fetal development was assessed. In addition, the animals were fed semisynthetic isocaloric diets containing either 8 or 20% casein. All animals were pair-fed to those in the group receiving ethanol and 20% casein; an additional control group was fed lab chow ad libitum. There was clearly an interactive effect of diet and ethanol consumption on blood alcohol concentrations: those in the low-protein group were significantly higher than in the normal-protein group. Similarly, the effect on body weight in the group receiving low protein plus ethanol was greater than the additive effect of either treatment alone, although this may have been due partly to differences in litter size. Brain weight in this group was also significantly less than in the other three groups, which did not differ from each other. Covariance analysis, adjusting brain weight for body weight, suggested a brain-sparing effect of low protein but not ethanol. Neither treatment affected the incidence of the CC being absent at midline. The low-protein treatment decreased the cross-sectional area of both the CC and CA; the effect on the CC was independent of brain weight. There was no effect of ethanol on either of those measures.