Chronic Prenatal Ethanol Exposure Research Articles

Prenatal ethanol exposure impairs spatial cognition and synaptic plasticity in female rats

Chronic prenatal ethanol exposure (CPEE) can impair long-term potentiation (LTP) in the male hippocampus. Sexually specific alterations were frequently reported in female animals that had been prenatally exposed to ethanol. This study aimed to examine the effects of CPEE on spatial learning and memory, as well as on hippocampal synaptic plasticity in female adolescent rats. Female offspring were selected from dams that had been exposed to 4 g/kg/day of ethanol throughout the gestational period. Subsequently, performance in the Morris water maze (MWM) was determined, while LTP and depotentiation were measured in the hippocampal CA3-CA1 pathway. In the behavioral test, the escape latencies in both initial and reversal training stages were significantly prolonged. Interestingly, LTP was considerably enhanced while depotentiation was significantly depressed. Our results suggest a critical role of synaptic plasticity balance, which may prominently contribute to the cognitive deficits present in CPEE offspring.

Unilateral whisker clipping exacerbates ethanol-induced social and somatosensory behavioral deficits in a sex- and age-dependent manner

Prenatal exposure to ethanol results in sensory deficits and altered social interactions in animal and clinical populations. Sensory stimuli serve as important cues and shape sensory development; developmental exposure to ethanol or sensory impoverishment can impair somatosensory development, but their combined effects on behavioral outcomes are unknown. We hypothesized 1) that chronic prenatal ethanol exposure would disrupt social interaction and somatosensory performance during adolescence, 2) that a mild sensory impoverishment (neonatal unilateral whisker clipping; WC) would have a mildly impairing to sub-threshold effect on these behavioral outcomes, and 3) that the effect of ethanol would be exacerbated by WC. Long–Evans dams were fed a liquid diet containing ethanol or pair-fed with a non-ethanol diet on gestational days (G) 6–G21. Chow-fed control animals were also included. One male and female pup per litter underwent WC on postnatal day (P)1, P3, and P5. Controls were unclipped. Offspring underwent social interaction on P28 or P42, and gap-crossing (GC) on P31 or P42. Ethanol-exposed pups played less and crossed shorter gaps than control pups regardless of age or sex. WC further exacerbated ethanol-induced play fighting and GC deficits in all males but only in 28-day-old females. WC alone reduced sniffing in all males and in younger females. Thus, prenatal ethanol exposure induced deficits in social interaction and somatosensory performance during adolescence. Sensory impoverishment exacerbates ethanol's effect in 28-day-old male and female animals and in 42-day-old males, suggesting sex- and age-dependent changes in outcomes in ethanol-exposed offspring.

Chronic prenatal ethanol exposure alters expression of central and peripheral insulin signaling molecules in adult guinea pig offspring

Maternal ethanol consumption during pregnancy can produce a range of teratogenic outcomes in offspring. The mechanism of ethanol teratogenicity is multi-faceted, but may involve alterations in insulin and insulin-like growth factor (IGF) signaling pathways. These pathways are not only important for metabolism, but are also critically involved in neuronal survival and plasticity, and they can be altered by chronic prenatal ethanol exposure (CPEE). The objective of this study was to test the hypothesis that CPEE alters expression of insulin and IGF signaling molecules in the prefrontal cortex and liver of adult guinea pig offspring. Pregnant Dunkin-Hartley-strain guinea pigs received ethanol (4 g/kg maternal body weight/day) or isocaloric-sucrose/pair-feeding (nutritional control) throughout gestation. Fasting blood glucose concentration was measured in male and female offspring at postnatal day 150–200, followed by euthanasia, collection of prefrontal cortex and liver, and RNA extraction. IGF-1, IGF-1 receptor (IGF-1R), IGF-2, IGF-2 receptor (IGF-2R), insulin receptor substrate (IRS)-1, IRS-2, and insulin receptor (INSR) mRNA expression levels were measured in tissues using quantitative real-time PCR. The mean maternal blood ethanol concentration was 281 ± 15 mg/dL at 1 h after the second divided dose of ethanol on GD 57. CPEE resulted in increased liver weight in adult offspring, but produced no difference in fasting blood glucose concentration compared with nutritional control. In the liver, CPEE decreased mRNA expression of IGF-1, IGF-1R, and IGF-2, and increased IRS-2 mRNA expression in male offspring only compared with nutritional control. Female CPEE offspring had decreased INSR hepatic mRNA expression compared with male CPEE offspring. In the prefrontal cortex, IRS-2 mRNA expression was increased in CPEE offspring compared with nutritional control. The data demonstrate that CPEE alters both central and peripheral expression of insulin and IGF signaling molecules at the mRNA level, which may be related to metabolic dysregulation in adult offspring. Furthermore, altered insulin and IGF signaling may be a mechanism of ethanol neurobehavioral teratogenicity.

Spatial cognition and sexually dimorphic synaptic plasticity balance impairment in rats with chronic prenatal ethanol exposure

Prenatal ethanol exposure can lead to long-lasting impairments in the ability of rats to process spatial information, as well as produce long-lasting deficits in long-term potentiation (LTP), a biological model of learning and memory processing. The present study aimed to examine the sexually dimorphic effects of chronic prenatal ethanol exposure (CPEE) on behavior cognition and synaptic plasticity balance (SPB), and tried to understand a possible mechanism by evaluating the alternation of SPB. The animal model was produced by ethanol exposure throughout gestational period with 4g/kg bodyweight. Offspring of both male and female were selected and studied on postnatal days 36. Subsequently, the data showed that chronic ethanol exposure resulted in birth weight reduction, losing bodyweight gain, microcephaly and hippocampus weight retardation. In Morris water maze (MWM) test, escape latencies were significantly higher in CPEE-treated rats than that in control ones. They also spent much less time in the target quadrant compared to that of control animals in the probe phase. In addition, it was found that there was a more severe impairment in females than that in males after CPEE treatment. Electrophysiological studies showed that CPEE considerably inhibited hippocampal LTP and facilitated depotentiation in males, while significantly enhanced LTP and suppressed depotentiation in females. A novel index, developed by us, showed that the action of CPEE on SPB was more sensitive in females than that in males, suggesting that it might be an effective index to distinguish the difference of SPB impairment between males and females.

Impact of Low Dose Prenatal Ethanol Exposure on Glucose Homeostasis in Sprague-Dawley Rats Aged up to Eight Months

Excessive exposure to alcohol prenatally has a myriad of detrimental effects on the health and well-being of the offspring. It is unknown whether chronic low-moderate exposure of alcohol prenatally has similar and lasting effects on the adult offspring’s health. Using our recently developed Sprague-Dawley rat model of 6% chronic prenatal ethanol exposure, this study aimed to determine if this modest level of exposure adversely affects glucose homeostasis in male and female offspring aged up to eight months. Plasma glucose concentrations were measured in late fetal and postnatal life. The pancreas of 30 day old offspring was analysed for β-cell mass. Glucose handling and insulin action was measured at four months using an intraperitoneal glucose tolerance test and insulin challenge, respectively. Body composition and metabolic gene expression were measured at eight months. Despite normoglycaemia in ethanol consuming dams, ethanol-exposed fetuses were hypoglycaemic at embryonic day 20. Ethanol-exposed offspring were normoglycaemic and normoinsulinaemic under basal fasting conditions and had normal pancreatic β-cell mass at postnatal day 30. However, during a glucose tolerance test, male ethanol-exposed offspring were hyperinsulinaemic with increased first phase insulin secretion. Female ethanol-exposed offspring displayed enhanced glucose clearance during an insulin challenge. Body composition and hepatic, muscle and adipose tissue metabolic gene expression levels at eight months were not altered by prenatal ethanol exposure. Low-moderate chronic prenatal ethanol exposure has subtle, sex specific effects on glucose homeostasis in the young adult rat. As aging is associated with glucose dysregulation, further studies will clarify the long lasting effects of prenatal ethanol exposure.

Chronic Prenatal Ethanol Exposure Disrupts WNT Signaling In Adolescent Cerebella

Background: In Fetal Alcohol Spectrum Disorder (FASD), structural and functional abnormalities in the cerebellum persist through adolescence and beyond. We hypothesize that perturbations in Wnt signaling may contribute to these effects because Wnt pathways mediate neuronal morphogenesis, migration, and plasticity during development. Objectives: We utilized an established model of FASD to assess the nature and degree to which chronic prenatal ethanol exposure impairs Wnt pathway gene expression in postnatal and adolescent cerebella. Methods: Pregnant Long Evans rats were fed isocaloric liquid diets containing 0%, 18% or 37% ethanol by caloric content from gestation day 6 through delivery. Offspring were sacrificed on postnatal day 3 (P3), P10, P20, or P35. Wnt pathway gene expression was examined using a targeted PCR array and duplex qRT-PCR analysis. Results: Among the 84 genes examined by targeted array, chronic prenatal ethanol exposure (37%) down-regulated just 3 genes at P10, but 33 genes at P35. Further analysis focusing on Wnt5a, Wnt5b, Fzd4, Fzd6, Axin2, Dixdc, and EP300 revealed that prenatal ethanol exposure enhanced expression of Fzd4, Fzd6, Axin2, Dixdc, and EP300 at P3 and Wnt5b at P20, but inhibited Fzd4 and EP300 at P10, and Fzd4, Fzd6, Wnt5a, and EP300 at P20. In addition, ß-catenin, Cyclin D1, and c-Myc protein expression was inhibited by ethanol exposure at P3, but not P10 or P20. To some extent responses were ethanol dose-dependent. Conclusions: The consequences of chronic prenatal ethanol exposure on Wnt signaling in the brain shift dramatically with developmental stage. The findings further suggest that Wnt functions such as plasticity, which are needed for adolescent brain development, should be therapeutically targeted in FASD.

Imbalanced Synaptic Plasticity Induced Spatial Cognition Impairment in Male Offspring Rats Treated with Chronic Prenatal Ethanol Exposure

As chronic prenatal ethanol (EtOH) exposure (CPEE) may cause deficiencies in a variety of behavioral and cognitive functions, the aim of present study is to investigate the effects of CPEE on spatial learning and memory and examine the action of CPEE on synaptic plasticity balance in the hippocampus of adolescent male rats. The animal model was produced by EtOH exposure throughout gestational period with 4 g/kg bodyweight, while the male offspring rats were used in the study. Morris water maze (MWM) test was performed, and then, long-term potentiation (LTP) and depotentiation were recorded from Schaffer collaterals to CA1 region in the hippocampus. It was shown that escape latencies in learning period and re-acquisition period were prolonged in CPEE-treated group compared with that in control group. Furthermore, LTP was drastically inhibited, and depotentiation was distinctly enhanced in CPEE-treated group compared with that in control group. It is suggested that the balance between cognitive stability and flexibility was broken by the bidirectional effects of long-term synaptic plasticity. In addition, the spatial cognition was attenuated by the alteration of synaptic plasticity balance in CPEE-treated male adolescent rats.

Chronic prenatal ethanol exposure increases adiposity and disrupts pancreatic morphology in adult guinea pig offspring

Background:Ethanol consumption during pregnancy can lead to a range of adverse developmental outcomes in children, termed fetal alcohol spectrum disorder (FASD). Central nervous system injury is a debilitating and widely studied manifestation of chronic prenatal ethanol exposure (CPEE). However, CPEE can also cause structural and functional deficits in metabolic pathways in offspring.Objectives and Methods:This study tested the hypothesis that CPEE increases whole-body adiposity and disrupts pancreatic structure in guinea pig offspring. Pregnant guinea pigs received ethanol (4 g kg−1 maternal body weight per day) or isocaloric-sucrose/pair-feeding (control) for 5 days per week throughout gestation.Results:Male and female CPEE offspring demonstrated growth restriction at birth, followed by a rapid period of catch-up growth before weaning (postnatal day (PD) 1–7). Whole-body magnetic resonance imaging (MRI) in young adult offspring (PD100–140) revealed increased visceral and subcutaneous adiposity produced by CPEE. At the time of killing (PD150–200), CPEE offspring also had increased pancreatic adipocyte area and decreased β-cell insulin-like immunopositive area, suggesting reduced insulin production and/or secretion from pancreatic islets.Conclusion:CPEE causes increased adiposity and pancreatic dysmorphology in offspring, which may signify increased risk for the development of metabolic syndrome and type 2 diabetes mellitus.

Sensitivity of modified Biel-maze task, compared with Y-maze task, to measure spatial learning and memory deficits of ethanol teratogenicity in the guinea pig

Ethanol consumption during pregnancy can produce a variety of teratogenic effects in offspring, termed Fetal Alcohol Spectrum Disorders (FASD). The most debilitating and permanent consequence of chronic prenatal ethanol exposure (CPEE) is neurobehavioral teratogenicity, which often manifests as cognitive and behavioral impairments, including deficits in spatial learning and memory. This study tested the hypothesis that a modified dry-land version of the multi-choice Biel-maze task is more sensitive than the rewarded-alternation Y-maze task for the determination of spatial learning and memory deficits of ethanol teratogenicity. Pregnant guinea pigs received ethanol (4g/kg maternal body weight/day) or isocaloric-sucrose/pair-feeding (control) for 5days/week throughout gestation. CPEE resulted in ethanol neurobehavioral teratogenicity in offspring, as demonstrated by increased spontaneous locomotor activity at postnatal day (PD) 10 and decreased brain weight at euthanasia (PD 150–200). On PD 21, offspring were randomly assigned to one of two tasks to assess spatial learning and memory performance: a dry-land version of the Biel maze or a rewarded-alternation Y-maze. Animals were habituated to the environment of their assigned task and performance of each CPEE or control offspring was measured. In the modified Biel maze, CPEE and control offspring were not different for percent completed trials or time to complete a trial. However, CPEE offspring made more errors (reversals and entering dead ends) in the Biel maze, demonstrating impaired spatial learning and memory. In contrast, CPEE offspring did not have impaired performance of the rewarded-alternation Y-maze task. Therefore, the modified dry-land version of the Biel-maze task, which measures cognitive performance using a complex multi-choice design, is more sensitive in demonstrating CPEE-induced spatial learning and memory deficits compared with a simple, rewarded-alternation Y-maze task.

Motor Function Deficits Following Chronic Prenatal Ethanol Exposure are Linked to Impairments in Insulin/IGF, Notch and Wnt Signaling in the Cerebellum

Fetal alcohol spectrum disorder (FASD) is associated with deficits in cerebellar function that can persist through adolescence. Previous studies demonstrated striking inhibition of insulin and insulin-like growth factor (IGF) signaling in ethanol-exposed cerebella. We sought to determine if FASD-induced impairments in motor function were associated with deficits in insulin/IGF signaling in juvenile cerebella. Given the growing evidence that insulin/IGF pathways cross-talk with Notch and Wnt to promote brain development and maturation; we also examined the integrity of canonical Wnt and Notch signaling networks in the brain following chronic prenatal ethanol exposure. Pregnant Long Evans rats were fed isocaloric liquid diets containing 0% or 24% ethanol by caloric content from gestation day 6 through delivery. Pups were subjected to rotarod testing on postnatal days (P) 15-16 and sacrificed on P30. Cerebella were used for molecular and biochemical analysis of insulin/IGF-1, canonical Wnt, and Notch signaling mechanisms. Prenatal ethanol exposures impaired rotarod performance, inhibited signaling through insulin and IGF-1 receptors, IRS-1, and Akt, increased activation of GSK-3β, and broadly suppressed genes mediating the canonical Wnt and Notch networks. Abnormalities in cerebellar function following chronic prenatal ethanol exposure are associated with inhibition of insulin/IGF, canonical Wnt, and Notch networks that cross-talk via GSK-3β. Effective therapeutic measures for FASD may require multi-pronged support of interrelated signaling networks that regulate brain development.

Chronic prenatal ethanol exposure increases disinhibition and perseverative responding in the adult guinea pig

Cognitive and behavioural deficits, including increased impulsivity and perseveration, are associated with chronic prenatal ethanol exposure (CPEE) in humans. We tested whether these same deficits occur in the guinea pig after CPEE treatment. Pregnant guinea pigs received oral administration of ethanol (4 g/kg maternal body weight/day), or isocaloric-sucrose/pair-feeding throughout gestation. Young adult offspring were trained in lever-pressing paradigms to work for a sucrose-pellet food reward. CPEE increased No-Go, but not Go, responses in the Go/No-Go paradigm, indicative of a disinhibition deficit in these animals. Perseverative responses in the Cued Alternation task were also increased in CPEE offspring. These data show that CPEE induces behavioural deficits in the guinea pig that are remarkably similar to the executive function deficits that follow prenatal ethanol exposure in humans.

Altered water–maze search behavior in adult guinea pigs following chronic prenatal ethanol exposure: Lack of mitigation by postnatal fluoxetine treatment

Ingestion of ethanol during pregnancy can result in teratogenic effects in humans, including significant and long-lasting neurobehavioral deficits. Similar results are seen in guinea pigs with chronic prenatal ethanol exposure (CPEE) via maternal ethanol administration, which produces deficits in Morris water–maze performance and impaired hippocampal functioning (e.g., decreased long-term potentiation, LTP). In this study, we tested whether postnatal treatment with fluoxetine, a selective serotonin reuptake inhibitor, decreases some of the neurobehavioral impairments produced by CPEE. Timed, pregnant guinea pigs received oral administration of ethanol (4g/kg maternal body weight) or isocaloric sucrose pair feeding (control) for 5 days/week throughout gestation. Offspring of the CPEE and control groups were randomly assigned to receive either fluoxetine (10mg/kg body weight/day) or saline intraperitoneally from postnatal day 10 to 48. Subsequent behavioral tests in the Morris water–maze revealed a significant increase in thigmotaxic swimming in CPEE offspring without apparent signs of impairment in spatial mapping of the hidden escape platform. Measures of hippocampal short- and long-term plasticity (paired-pulse facilitation, frequency facilitation, and LTP) were unaffected by CPEE, consistent with the behavioral data indicating normal hippocampal functioning. Postnatal fluoxetine administration resulted in a significant loss of body weight, but did not affect the increased thigmotaxic swimming following CPEE. These results indicate that changes in search strategies in the water–maze might be a highly sensitive index of CPEE-induced neurobehavioral toxicity that can occur in the absence of significant hippocampal dysfunction. Further, these data demonstrate that fluoxetine, at the selected treatment regime, does not mitigate the thigmotaxic swimming response to CPEE in the guinea pig.

Chronic Prenatal Ethanol Exposure Increases Glucocorticoid‐Induced Glutamate Release in the Hippocampus of the Near‐Term Foetal Guinea Pig

Exposure to high cortisol concentration can injure the developing brain, possibly via an excitotoxic mechanism involving glutamate (Glu). The present study tested the hypothesis that chronic prenatal ethanol exposure (CPEE) activates the foetal hypothalamic-pituitary-adrenal axis to produce high cortisol exposure in the foetal compartment and alters sensitivity to glucocorticoid-induced Glu release in the foetal hippocampus. Pregnant guinea pigs received daily oral administration of ethanol (4 g/kg maternal body weight/day) or isocaloric-sucrose/pair-feeding from gestational day (GD) 2 until GD 63 (term, approximately GD 68) at which time they were euthanised, 1 h after their final treatment. Adrenocorticotrophic hormone (ACTH) and cortisol concentrations were determined in foetal plasma. Basal and electrically stimulated Glu and gamma-aminobutyric acid (GABA) efflux in the presence or absence of dexamethasone (DEX), a selective glucocorticoid-receptor agonist, were determined ex vivo in foetal hippocampal slices. Glucocorticoid receptor (GR), mineralocorticoid receptor (MR) and N-methyl-D-aspartate (NMDA) receptor NR1 subunit mRNA expression were determined in situ in the hippocampus and dentate gyrus. In the near-term foetus, CPEE increased foetal plasma ACTH and cortisol concentrations. Electrically stimulated glutamate, but not GABA, release was increased in CPEE foetal hippocampal slices. Low DEX concentration (0.3 microM) decreased stimulated glutamate, but not GABA, release in both CPEE and control foetal hippocampal slices. High DEX concentration (3.0 microM) increased basal release of Glu, but not GABA, in CPEE foetal hippocampal slices. GR, but not MR, mRNA expression was elevated in the hippocampus and dentate gyrus, whereas NR1 mRNA expression was increased in the CA1 and CA3 fields of the foetal hippocampus. These data demonstrate that CPEE increases high glucocorticoid concentration-induced Glu release in the foetal hippocampus, presumably as a consequence of increased GR expression. These effects of CPEE, coupled with increased glutamate release and increased NMDA receptor expression, may predispose the near-term foetal hippocampus to GR and Glu-NMDA receptor-mediated neurodevelopmental toxicity.

Chronic Prenatal Ethanol Exposure and Increased Concentration of Fatty Acid Ethyl Esters in Meconium of Term Fetal Guinea Pig

In humans, the occurrence of prenatal exposure to ethanol is difficult to validate objectively. Increased concentration of fatty acid ethyl esters (FAEE) in the meconium of the newborn may be a biomarker of prenatal ethanol exposure. The validity of this proposed biomarker was tested in pregnant guinea pigs that received chronic oral administration of 4 g ethanol/kg maternal body weight/day (n=8), isocaloric-sucrose/pair-feeding (n=8) or water (n=2) throughout gestation. At gestational day 65 (term, gestational day 66 to 69), each dam and her offspring were euthanized, and meconium was collected from the term fetal large intestine. Eight individual FAEE (lauric, myristic, palmitic, palmitoleic, stearic, oleic, linolenic and arachidonic AEE) were measured by gas chromatography--flame ionization detection and confirmed by gas chromatography--mass spectrometry. The chronic maternal ethanol regimen decreased fetal body weight and brain weight. There was virtually no measurable FAEE in the meconium for the water group (n=3 fetuses). For meconium of the ethanol offspring (n=25 fetuses) compared with the sucrose offspring (n=23 fetuses), the total FAEE concentration was 8-fold higher; and lauric, palmitic, stearic and oleic AEE concentrations were at least 5-fold higher for the ethanol group. The data indicate that fetal meconium FAEE constitute a biomarker of prenatal ethanol exposure for a maternal ethanol regimen that restricts fetal development, with an inverse relationship between meconium total FAEE concentration and both body weight and brain weight.

Spatial learning deficits induced by chronic prenatal ethanol exposure can be overcome by non-spatial pre-training

This study tested the hypothesis that behavioural intervention, in the form of non-spatial pre-training, mitigates the deficits in spatial learning tasks induced in guinea pig offspring by chronic prenatal ethanol exposure (CPEE). Timed, pregnant guinea pigs were treated with ethanol (4 g/kg maternal body weight/day), isocaloric-sucrose/pair-feeding, or water throughout gestation. Offspring received non-spatial pre-training, in which animals were exposed to the procedural requirements of the water maze in the absence of distal spatial cues, and then were tested in both stationary-platform and moving-platform tasks with spatial cues. Saliva cortisol was quantified in non-trained and pre-trained animals before and after exposure to the water maze. Results CPEE offspring exhibited performance deficits in the stationary-platform task, and non-spatial pre-training improved performance of CPEE offspring to control levels. In contrast, non-spatial pre-training had no effect on the impaired performance of CPEE offspring in the moving-platform task. Non-trained CPEE offspring had elevated saliva cortisol concentration after water-maze exposure compared to control offspring. Moreover, pre-trained control animals exhibited a sensitization of the cortisol response after repeated exposure to the water maze, and this was not evident in pre-trained CPEE offspring. Conclusions These data demonstrate that CPEE produced deficits in spatial learning and memory processes that were partially overcome by non-spatial pre-training; however, more difficult tasks continued to reveal cognitive deficits. For repeated exposure to the water maze, CPEE offspring achieved a level of performance that was not different from control offspring, suggesting that it is the initial rate of acquisition of new learning, rather than the overall ability to learn, that is most adversely affected by CPEE.

Alcohol increases efficacy of immature synapses in a neurosteroid‐dependent manner

Fetal ethanol exposure persistently affects hippocampal circuits leading to learning and memory disabilities. Although the mechanisms responsible for these effects are not fully understood, several studies implicate neurosteroids as mediators of the actions of ethanol. A neurosteroid that appears to be critical for the fetal actions of ethanol is pregnenolone sulfate (PREGS). We found that chronic prenatal ethanol exposure increases PREGS levels in the fetal brain and that an endogenous PREGS-like neurosteroid strengthens excitatory transmission in the neonatal hippocampus. Therefore, we hypothesized that ethanol could affect synaptic transmission in the developing hippocampus in a PREGS-dependent manner. We used patch-clamp electrophysiological techniques and found that 50 mm ethanol strengthens AMPA receptor-mediated transmission in the CA1 region by reducing the failure rate of low-efficacy synapses. This effect was age-dependent and was occluded by application of exogenous PREGS. An anti-PREGS antibody scavenger and blockade of PREGS synthesis prevented the effect of ethanol. These data indicate that the deleterious effects of ethanol on hippocampal development are mediated in part by alterations in neurosteroid production, which results in premature stabilization of excitatory synapses.

Effects of chronic prenatal ethanol exposure on mitochondrial glutathione and 8-iso-prostaglandin F2α concentrations in the hippocampus of the perinatal guinea pig

It is hypothesised that oxidative stress is a key mechanism of ethanol neurobehavioural teratogenicity, resulting in altered endogenous antioxidant status and increased membrane lipid peroxidation in the hippocampus of chronic prenatal ethanol exposure (CPEE) offspring. To test this hypothesis, timed pregnant guinea-pigs (term, approximately gestational day (GD) 68) received chronic daily oral administration of (i) 4 g ethanol kg(-1) maternal bodyweight, (ii) isocaloric sucrose with pair feeding, or (iii) water. At GD 65 (term fetus) and postnatal day (PD) 0 (neonate), individual offspring were killed, the brain was excised and the hippocampi were dissected. Glutathione (GSH) concentration was measured in the cytosolic and mitochondrial fractions of hippocampal homogenate. The occurrence of lipid peroxidation was determined by measuring the concentration of 8-iso-prostaglandin F2+/- (8-iso-PGF2+/-). There was CPEE-induced decreased brain weight and hippocampal weight at GD 65 and PD 0, decreased mitochondrial GSH concentration in the hippocampus at PD 0, with no change in mitochondrial GSH concentration at GD 65 or cytosolic GSH concentration at GD 65 or PD 0, and no change in mitochondrial or whole-homogenate 8-iso-PGF2+/- concentration in the hippocampus at GD 65 or PD 0. The data demonstrate that CPEE produces selective mitochondrial dysfunction in the hippocampus of the neonatal guinea-pig, involving GSH depletion.

The Effect of Chronic Prenatal Ethanol Exposure on Fetal Guinea Pig Cerebral Cortical and Hippocampal Glutamate Receptor Protein Expression

The Effect of Chronic Prenatal Ethanol Exposure on Fetal Guinea Pig Cerebral Cortical and Hippocampal Glutamate Receptor Protein Expression

Chronic prenatal ethanol exposure increases apoptosis in the hippocampus of the term fetal guinea pig

It is hypothesized that chronic prenatal ethanol exposure (CPEE), via maternal ethanol administration, increases mitochondrial-directed apoptosis in the hippocampus of the term fetus that precedes loss of hippocampal CA1 pyramidal cells. To test this hypothesis, timed pregnant guinea pigs received chronic oral administration of: 4 g ethanol/kg maternal body weight/day, isocaloric-sucrose/pair-feeding or water throughout gestation. At gestational day 65 (term fetus) and postnatal day 0 (neonate), individual offspring were euthanized, and the brain was excised and dissected. CPEE, compared with the isocaloric-sucrose/pair-fed and water control groups, decreased the brain weight of the term fetus and neonate. CPEE did not alter the density of CA1 pyramidal cells in the hippocampus of the term fetus and neonate. In the term fetus, CPEE increased cytochrome c content in the cytosolic fraction of the hippocampus, altered the mitochondrial localization of cytochrome c in cells of the dorsal hippocampus, and increased the percentage of cells in the dorsal hippocampus containing activated caspase-3 and cleaved poly(ADP-ribose) polymerase. The data indicate that CPEE increases neuroapoptosis in the hippocampus of term fetus, which appears to occur via an intrinsic, mitochondrial-directed mechanism initiated by leakage of pro-apoptotic cytochrome c from mitochondria into the cytoplasm.

Chronic Prenatal Ethanol Exposure Alters Glucocorticoid Signalling in the Hippocampus of the Postnatal Guinea Pig

The present study tested the hypothesis that chronic prenatal ethanol exposure causes long-lasting changes in glucocorticoid signalling in postnatal offspring. Pregnant guinea pigs were treated with ethanol (4 g/kg maternal body weight/day), isocaloric-sucrose/pair-feeding or water throughout gestation, and maternal saliva cortisol concentration was determined 2 h after treatment at different stages of gestation. Electrically-stimulated release of glutamate and GABA, in the presence or absence of dexamethasone, as well as glucocorticoid and mineralocorticoid receptor mRNA expression, was determined in the hippocampus and prefrontal cortex of adult offspring of treated pregnant guinea pigs. Maternal saliva cortisol concentration increased throughout pregnancy, which was associated with increased foetal plasma and amniotic fluid cortisol concentration. Ethanol administration to pregnant guinea pigs increased maternal saliva cortisol concentration during early and mid-gestation. In late gestation, ethanol administration did not increase saliva cortisol concentration above that induced by pregnancy. Chronic prenatal ethanol exposure had no effect on stimulated glutamate or GABA release, but selectively prevented dexamethasone-mediated suppression of stimulated glutamate release, and decreased expression of mineralocorticoid, but not glucocorticoid, receptor mRNA in the hippocampus of adult offspring. These data indicate that maternal ethanol administration leads to excessively increased maternal cortisol concentration that can impact negatively the developing foetal brain, leading to persistent postnatal deficits in glucocorticoid regulation of glutamate signalling in the adult hippocampus.