Early Postnatal Ethanol Exposure Research Articles

Maternal Ethanol Exposure Impairs the Kidney of Offspring by Alteration of Podocyte Proteins Genes Expression and Fibrosis

Background: This study examined the effect of prenatal and early postnatal ethanol exposure on the structural, functional, and molecular alterations of rat’s offspring kidney on postnatal days 21 and 90.Methods: Pregnant rats on gestation day 7 were divided into the two groups, namely control and ethanol groups. Rats in the ethanol group received ethanol (4.5 g/kg B.W) from gestation day 7 throughout lactation. Nephrin, podocin, vascular endothelial growth factor receptors (VEGFRs) 1 and 2 gene expression were measured by RT-PCR technique. The MMP2 and MMP9 levels in the kidney tissue and plasma cystatin C level were measured by ELISA method.Results: The results revealed a significant alteration in mRNA expression of nephrin, podocin, and VEGFR, as well as MMPs amounts in the kidneys of the offspring. Cystatin C level, the ratio of cystatin C/serum creatinine, serum creatinine, and urine urea showed a significant increase, but urine creatinine and GFR showed a significant decrease in the offsprings of the ethanol group compared to the control group. Histopathological changes such as fibrosis, kidney cells proliferation, leukocytes infiltration, and vacuolization have also seen in the kidney of the offsprings after 21 and 90 days from birth.Conclusion: Taken together, these results provide evidence that pre and early postnatal ethanol exposure renal toxicity is in part associated with alteration of nephrin, podocin, and VEGFRs genes expression, as well as MMPs amount changes. Furthermore, it was found that these molecular alterations were triggered by inflammatory reactions manifested by fibrosis, proliferation, and polymorphonuclear(PMN) leukocytes infiltration.

N-Methyl-d-Aspartate Receptor Modulation by Nicotinamide Adenine Dinucleotide Phosphate Oxidase Type 2 Drives Synaptic Plasticity and Spatial Memory Impairments in Rats Exposed Pre- and Postnatally to Ethanol.

Aims: Pre- and/or early postnatal ethanol exposure (prenatal alcohol exposure [PAE]) impairs synaptic plasticity as well as memory formation, but the mechanisms underlying these effects remain unclear. Both long-term potentiation (LTP) and spatial memory formation in the hippocampus involve the nicotinamide adenine dinucleotide phosphate oxidase type 2 (NOX2) enzyme. Previous studies have reported that N-methyl-d-aspartate receptor (NMDAR) activation increases NOX2-mediated superoxide generation, resulting in inhibition of NMDAR function, but whether NOX2 impacts NMDAR function in PAE animals leading to impaired LTP and memory formation remains unknown. We aim to evaluate whether the NOX2-NMDAR complex is involved in the long-lasting deleterious effects of PAE on hippocampal LTP and memory formation. Results: Here we provide novel evidence that PAE animals display impaired NMDAR-dependent LTP in the cornus ammonis field 1 (CA1) and NMDAR-mediated LTP in the dentate gyrus (DG). Moreover, PAE rats displayed increased NMDAR-mediated transmission in both hippocampal areas. Interestingly, NOX2 pharmacological inhibition restored NMDAR-mediated transmission and LTP in the CA1, but not in the DG. PAE also induced overexpression of NOX2 and CaMKII isoforms, but did not modify the content or the redox state of the N-methyl-d-aspartate receptor subunit-1 (NR1) subunit of NMDAR in both areas of the hippocampus. In addition, adolescent PAE rats orally fed the antioxidant and free radical scavenger apocynin exhibited significantly improved spatial memory acquisition. Innovation and Conclusion: By showing in PAE animals NOX2 overexpression and increased NMDAR-mediated transmission, which might lead to impaired synaptic plasticity and memory formation in a region-specific manner, we provide an important advance to our current understanding of the cellular mechanisms underlying PAE-dependent defective hippocampal function.

Early Postnatal Ethanol Exposure in Mice Induces Sex-Dependent Memory Impairment and Reduction of Hippocampal NMDA-R2B Expression in Adulthood

Drinking alcohol during pregnancy is particularly detrimental for the developing brain and may cause a broad spectrum of cognitive and behavioral impairments, collectively known as fetal alcohol spectrum disorder (FASD). While behavioral abnormalities and brain damage have been widely investigated in animal models of FASD, the sex differences in the vulnerability to perinatal ethanol exposure have received less consideration. Here we investigated the long-term behavioral and molecular effects of acute ethanol-binge like exposure during the early postnatal period (equivalent to the third trimester of human pregnancy) in adult male and female mice. CD1 mice received a single ethanol exposure on P7 and were analyzed starting from P60. We found that ethanol-exposed mice showed increased activity in the open field test and in the plus-maze test, regardless of the sex. Interestingly, only ethanol-exposed adult male mice exhibited memory impairment in the water maze and fear-conditioning tests. Remarkably, hippocampal levels of NMDA-R2B were reduced only in ethanol-exposed male, while total BDNF levels were increased in both male and female ethanol-exposed mice.Our data suggest a different susceptibility of early postnatal ethanol exposure in male and female CD1 mice.

Prenatal ethanol exposure potentiates isolation-induced ethanol consumption in young adult rats.

Prenatal and/or early postnatal ethanol exposure (PEE) is associated with significant behavioral and physiological deficits in offspring, including alterations in stress response systems and a greater likelihood of alcohol use disorders. Stress-induced ethanol drinking after PEE, however, has been largely unexplored. The present study analyzed ethanol intake in male Sprague-Dawley rats after protracted prenatal and early postnatal ethanol exposure and tested whether social isolation during the sensitive period of adolescence modulates the effects of PEE on ethanol drinking. The dams were given 10% ethanol (or its vehicle) as the sole drinking fluid from gestational day 0 (GD0) to postnatal day 7 (PD7). On PD21, male offspring were housed individually (isolated housing group) or in pairs in standard cages (standard housing group). From PD56 to PD84, these male rats were tested for ethanol intake in 24-h, intermittent two-bottle choice sessions that were conducted across 4 weeks. Maternal ethanol consumption during gestation and during the first week of life of the offspring averaged 6.10-8.20g/kg/22h. Isolation housing during adolescence increased free-choice ethanol drinking in young adulthood. The main novel finding was that this facilitative effect of isolation on absolute and percent ethanol intake was significantly greater in PEE rats than in control counterparts not exposed to the prenatal and early postnatal ethanol exposure (effect sizes [η2p]: 0.24-0.32). The present results suggest that PEE renders the individual sensitive to the facilitative effect of stress exposure on ethanol intake.

NADPH Oxidase Isoform 2 (NOX2) Is Involved in Drug Addiction Vulnerability in Progeny Developmentally Exposed to Ethanol.

Ethanol exposure increases oxidative stress in developing organs, including the brain. Antioxidant treatment during maternal ethanol ingestion improves behavioral deficits in rodent models of fetal alcohol spectrum disorder (FASD). However, the impact of general antioxidant treatment in their adult offspring and the Specific Reactive Species (ROS)-dependent mechanism, are not fully understood. We hypothesized that pre and early postnatal ethanol exposure (PEE) modifies redox homeostasis, in particular NOX2 function during reward signaling in the mesocorticolimbic pathway, which reinforces the effects of alcohol. We developed a FASD rat model which was evaluated during adolescence (P21) and adulthood (P70). We first studied whether redox homeostasis is affected in PEE animals, by analyzing mRNA expression of SOD1, CAT, and Gpx1. We found that PEE reduced the mRNA levels of these three anti-oxidant enzymes in PFC and HIPP at P21 and in the VTA at P70. We also analyzed basal mRNA and protein expression of NOX2 subunits such as gp91phox, p22 phox, and p47 phox, in mesocorticolimbic brain areas of PEE rat brains. At P21, gp91 phox, and p47 phox levels in the VTA were decreased. At P70, gp91 phox mRNA levels was decreased in HIPP and both mRNA and protein levels were decreased in PFC. Since NOX2 is regulated by the N-methyl-D-aspartate Receptor (NMDAR), we analyzed NMDAR mRNA expression and found differential expression of NMDAR subunits (NR1 and NR2B) in the PFC that was age dependent, with levels decreased at P21 and increased at P70. The analysis also revealed decreased NR2B mRNA expression in HIPP and VTA at P70. Offspring from maternal ethanol users consumed 25% more ethanol in a free choice alcohol consumption test than control rats, and showed place preference for an alcohol-paired compartment. In vivo inhibition of NOX2 using apocynin in drinking water, or infusion of blocked peptide gp91 phox ds in the VTA normalized alcohol place preference, suggesting that NOX2 plays an important role in addictive like behavior. Taken together, PEE significantly affects the expression of antioxidant enzymes, NOX2, NMDAR in an age, and brain region dependent manner. Moreover, we demonstrate that NOX2 regulates alcohol seeking behavior.

Gypenosides protected the neural stem cells in the subventricular zone of neonatal rats that were prenatally exposed to ethanol.

Fetal alcohol spectrum disorder (FASD) can cause severe mental retardation in children who are prenatally exposed to ethanol. The effects of prenatal and early postnatal ethanol exposure on adult hippocampal neurogenesis have been investigated; however, the effects of prenatal ethanol exposure on the subventricular zone (SVZ) have not. Gypenosides (GPs) have been reported to have neuroprotective effects in addition to other bioactivities. The effects of GPs on neural stem cells (NSCs) in the FASD model are unknown. Here, we test the effect of prenatal ethanol exposure on the neonatal SVZ, and the protection potential of GPs on NSCs in FASD rats. Our results show that prenatal ethanol exposure can suppress the cell proliferation and differentiation of neural stem cells in the neonatal SVZ and that GPs (400 mg/kg/day) can significantly increase the cell proliferation and differentiation of neural stem cells inhibited by ethanol. Our data indicate that GPs have neuroprotective effects on the NSCs and can enhance the neurogenesis inhibited by ethanol within the SVZ of neonatal rats. These findings provide new evidence for a potential therapy involving GPs for the treatment of FASD.

Early Postnatal Ethanol Exposure: Glutamatergic Excitotoxic Cell Death During Acute Withdrawal

Using a rat model of binge drinking during the third trimester of pregnancy, we investigated neural markers of glutamatergic activity and cell death during the acute post-ethanol withdrawal period in rats. Ethanol-exposed animals demonstrated increases in markers for glutamatergic activity (NMDA receptors 1 and c-Fos immunoreactivity) and apoptotic cell death (caspase-3 immunoreactivity and cells having fragmented or condensed nuclei identified by Hoechst 33342 staining) in the CA1 and CA3 subfields and dentate gyrus of the hippocampus. Ethanol exposure also increased markers for glutamatergic activity and apoptotic cell death in the prefrontal cortex, dorsal striatum, somatosensory cortex, and motor cortex. The facts that markers for glutamatergic activity and cell death were both elevated in the areas examined, and the magnitudes of the elevation in the two sets of markers correlated negatively, are consistent with a causal link between the two. The results support the hypothesis that NMDA-mediated excitotoxic cell death is involved in neuropathological events that follow ethanol exposures.

Effects of early postnatal exposure to ethanol on retinal ganglion cell morphology and numbers of neurons in the dorsolateral geniculate in mice.

The adverse effects of fetal and early postnatal ethanol intoxication on peripheral organs and the central nervous system are well documented. Ocular defects have also been reported in about 90% of children with fetal alcohol syndrome, including microphthalmia, loss of neurons in the retinal ganglion cell (RGC) layer, optic nerve hypoplasia, and dysmyelination. However, little is known about perinatal ethanol effects on retinal cell morphology. Examination of the potential toxic effects of alcohol on the neuron architecture is important because the changes in dendritic geometry and synapse distribution directly affect the organization and functions of neural circuits. Thus, in the present study, estimations of the numbers of neurons in the ganglion cell layer and dorsolateral geniculate nucleus (dLGN), and a detailed analysis of RGC morphology were carried out in transgenic mice exposed to ethanol during the early postnatal period. The study was carried out in male and female transgenic mice expressing yellow fluorescent protein (YFP) controlled by a Thy-1 (thymus cell antigen 1) regulator on a C57 background. Ethanol (3 g/kg/d) was administered to mouse pups by intragastric intubation throughout postnatal days (PDs) 3 to 20. Intubation control (IC) and untreated control (C) groups were included. Blood alcohol concentration was measured in separate groups of pups on PDs 3, 10, and 20 at 4 different time points, 1, 1.5, 2, and 3 hours after the second intubation. Numbers of neurons in the ganglion cell layer and in the dLGN were quantified on PD20 using unbiased stereological procedures. RGC morphology was imaged by confocal microscopy and analyzed using Neurolucida software. Binge-like ethanol exposure in mice during the early postnatal period from PDs 3 to 20 altered RGC morphology and resulted in a significant decrease in the numbers of neurons in the ganglion cell layer and in the dLGN. In the alcohol exposure group, out of 13 morphological parameters examined in RGCs, soma area was significantly reduced and dendritic tortuosity significantly increased. After neonatal exposure to ethanol, a decrease in total dendritic field area and an increase in the mean branch angle were also observed. Interestingly, RGC dendrite elongation and a decrease in the spine density were observed in the IC group, as compared to both ethanol-exposed and pure control subjects. There were no significant effects of alcohol exposure on total retinal area. Early postnatal ethanol exposure affects development of the visual system, reducing the numbers of neurons in the ganglion cell layer and in the dLGN, and altering RGCs' morphology.

Voluntary exercise induces adult hippocampal neurogenesis and BDNF expression in a rodent model of fetal alcohol spectrum disorders

Alcohol consumption during pregnancy can result in a myriad of health problems in the affected offspring ranging from growth deficiencies to central nervous system impairments that result in cognitive deficits. Adult hippocampal neurogenesis is thought to play a role in cognition (i.e. learning and memory) and can be modulated by extrinsic factors such as alcohol consumption and physical exercise. We examined the impact of voluntary physical exercise on adult hippocampal neurogenesis in a rat model of fetal alcohol spectrum disorders (FASD). Intragastric intubation was used to deliver ethanol to rats in a highly controlled fashion through all three trimester equivalents (i.e. throughout gestation and during the first 10 days of postnatal life). Ethanol-exposed animals and their pair-fed and ad libitum controls were left undisturbed until they reached a young adult stage at which point they had free access to a running wheel for 12 days. Prenatal and early postnatal ethanol exposure altered cell proliferation in young adult female rats and increased early neuronal maturation without affecting cell survival in the dentate gyrus (DG) of the hippocampus. Voluntary wheel running increased cell proliferation, neuronal maturation and cell survival as well as levels of brain-derived neurotrophic factor in the DG of both ethanol-exposed female rats and their pair-fed and ad libitum controls. These results indicate that the capacity of the brain to respond to exercise is not impaired in this model of FASD, highlighting the potential therapeutic value of physical exercise for this developmental disorder.

Early ethanol exposure in mice increases laterality of rotational side preference in the free-swimming test

In order to test the hypothesis that early postnatal ethanol exposure has long lasting behavioral effects that include changes to the normal pattern of cerebral asymmetries, the free swimming test (FST) was used to study the behavior of adult Swiss mice (males and females) exposed to ethanol during the third trimester equivalent of human gestation. Animals received ethanol (5 g/Kg ip, ETOH group) or saline (CONT group) on alternate days from postnatal day ( P) 2 to P8, and were submitted to 1 session of open field (OF) and 3 sessions of FST from P75 to P81. No differences between ETOH and CONT groups were observed in OF. However, the FST revealed significant differences between ETOH and CONT mice during the first session. The percentage of animals that presented strong turning preferences (especially to the right side) was higher in the ETOH group when compared with the CONT group. These data give support to the hypothesis that early ethanol exposure affects cerebral asymmetries and suggests that the FST is a useful tool to investigate the long-lasting effects of ethanol exposure during development.

Early postnatal ethanol exposure induces fluctuation in the expression of BDNF mRNA in the developing rat hippocampus.

Effects of early postnatal ethanol exposure on brain-derived neurotrophic factor (BDNF) mRNA expression in the rat hippocampus were investigated. Wistar rats were assigned to either ethanol treatment (ET) separation control (SC) or mother-reared control (MRC) groups. Ethanol exposure was achieved by a vapor inhalation method for 3 hours a day between postnatal days (PND) 1015. On PND 16, 20, 30, and 60, the expression of BDNF mRNA in the hippocampus was determined using real-time RT-PCR analysis. There was a significant age-related increase in the BDNF mRNA expression between PND 3060 in MRC animals. The BDNF mRNA expression in ET rats was increased at both PND 16 and 20 and thereafter decreased at PND 60 compared to SC animals. Such age-related fluctuation in the expression of BDNF mRNA differed from that of MRC animals. The exact functional implications, if any, of these ethanol-induced changes in BDNF mRNA expression remain unknown although it can be speculated that they may have an effect on the behaviors known to be influenced by the hippocampal formation.

Ethanol neurotoxicity and dentate gyrus development

Maternal alcohol ingestion during pregnancy adversely affects the developing fetus, often leading to fetal alcohol syndrome (FAS). One of the most severe consequences of FAS is brain damage that is manifested as cognitive, learning, and behavioral deficits. The hippocampus plays a crucial role in such abilities; it is also known as one of the brain regions most vulnerable to ethanol-induced neurotoxicity. Our recent studies using morphometric techniques have further shown that ethanol neurotoxicity appears to affect the development of the dentate gyrus in a region-specific manner; it was found that early postnatal ethanol exposure causes a transitory deficit in the hilus volume of the dentate gyrus. It is strongly speculated that such structural modifications, even transitory ones, appear to result in developmental abnormalities in the brain circuitry and lead to the learning disabilities observed in FAS children. Based on reports on possible factors deciding ethanol neurotoxicity to the brain, we review developmental neurotoxicity to the dentate gyrus of the hippocampal formation.

A single day of ethanol exposure during development has persistent effects on bi-directional plasticity, N-methyl- d-aspartate receptor function and ethanol sensitivity

To determine factors that contribute to the learning deficits observed in individuals with fetal alcohol syndrome, we examined the effects of early postnatal ethanol exposure on forms of synaptic plasticity thought to underlie memory. Treatment of rat pups with ethanol on postnatal day 7 impaired the induction of N-methyl- d-aspartate receptor-dependent long-term potentiation and abolished homosynaptic long-term depression in the CA1 region of hippocampal slices prepared at postnatal day 30. An N-methyl- d-aspartate receptor-independent form of long-term potentiation induced by very high frequency stimulation could be induced in slices from ethanol-treated rats. Defects in long-term depression correlated with a diminished contribution of ifenprodil-sensitive N-methyl- d-aspartate receptors to synaptic transmission and defects in a spontaneous alternation behavioral task. Rats exposed to ethanol on postnatal day 7 also exhibited diminished sensitivity of synaptic N-methyl- d-aspartate receptors to block by ethanol at postnatal day 30 and decreased behavioral sedation to systemic ethanol injections. These results indicate that changes in synaptic plasticity and N-methyl- d-aspartate receptor function are likely to provide a neural substrate for the cognitive and behavioral changes that follow developmental ethanol exposure.

Early postnatal ethanol exposure selectively decreases BDNF and truncated TrkB-T2 receptor mRNA expression in the rat cerebellum

Binge-like ethanol exposure on postnatal day (PN) 4 induces a concentration dependent loss of Purkinje cells in the rat cerebellum. The mechanism of this ethanol-induced Purkinje cell vulnerability is not presently understood. Nevertheless, the specific timing of this vulnerability leads us to consider the neurotrophin system crucial to the regulation of neuronal development. Differentiation, maturation, and survival of Purkinje cells are shown to involve an intimate interaction between brain-derived nerve growth factor (BDNF) and neurotrophin-3 (NT3) acting primarily through their specific tyrosine-kinase (Trk) receptors. We believe that the specific ethanol vulnerability, and the timing of this vulnerability result from alterations in the BDNF-NT3 interplay. We hypothesize that disruption of TrkB and/or TrkC mediated neurotrophin communication is, in part, responsible for the ethanol-induced loss of Purkinje cells during development. The current study was undertaken to define the impact of ethanol exposure at the onset of ethanol vulnerability on the relative concentrations of mRNA encoding the neurotrophic factor receptors TrkB and TrkC. The reverse transcriptase (RT) polymerase chain reaction (PCR) amplification technique was used to identify the relative expression levels of mRNA specific to these receptors as well as the truncated TrkB receptor isoforms. We identify a specific decrease in overall TrkB receptor mRNA expression that is primarily a function of the TrkB-T2 receptor isoform. Concurrent decreases in mRNA specific to BDNF were also identified. No significant alterations to the expression of TrkC mRNA were found indicating that ethanol-exposure appears to act selectively on the BDNF communication system.

A Review of the Effects of Prenatal or Early Postnatal Ethanol Exposure on Brain Ligand‐Gated Ion Channels

Ligand-gated ion channels mediate fast excitatory and inhibitory synaptic transmission in the developing central nervous system. These channels have been shown to have roles in neuronal proliferation, differentiation, and programmed cell death. Numerous studies over the past 10 years indicate that prenatal and/or early postnatal ethanol exposure affects neurotransmitter-gated ion channels. We conducted a review of the relevant literature, identified by a computer-assisted literature search. This review presents an overview of studies performed with experimental preparations from the brains of rodents exposed to ethanol in utero and/or during the neonatal period and summarizes some of the salient issues that have developed in the course of these investigations. Differences in ethanol exposure paradigms and blood alcohol concentrations obtained in these studies are highlighted, and directions for future research are suggested. Most studies have focused on the effects of prenatal or early postnatal ethanol exposure on NMDA receptors. These studies show that ethanol exposure affects ligand binding, subunit expression, and function of this receptor. Fewer studies have examined ethanol's effects on ligand-gated ion channels other than NMDA receptors. For instance, a study reported changes in ligand binding to hippocampal kainate receptors. Another study found alterations in modulation of GABA(A) receptors by benzodiazepines and neurosteroids. These studies suggest that the effects of ethanol on brain ion channels may have a role in the pathophysiology of Alcohol-Related Neurodevelopmental Disorders and Fetal Alcohol Syndrome.

A Review of the Effects of Prenatal or Early Postnatal Ethanol Exposure on Brain Ligand-Gated Ion Channels

Background: Ligand-gated ion channels mediate fast excitatory and inhibitory synaptic transmission in the developing central nervous system. These channels have been shown to have roles in neuronal proliferation, differentiation, and programmed cell death. Numerous studies over the past 10 years indicate that prenatal and/or early postnatal ethanol exposure affects neurotransmitter-gated ion channels. Methods: We conducted a review of the relevant literature, identified by a computer-assisted literature search. This review presents an overview of studies performed with experimental preparations from the brains of rodents exposed to ethanol in utero and/or during the neonatal period and summarizes some of the salient issues that have developed in the course of these investigations. Differences in ethanol exposure paradigms and blood alcohol concentrations obtained in these studies are highlighted, and directions for future research are suggested. Results: Most studies have focused on the effects of prenatal or early postnatal ethanol exposure on NMDA receptors. These studies show that ethanol exposure affects ligand binding, subunit expression, and function of this receptor. Fewer studies have examined ethanol's effects on ligand-gated ion channels other than NMDA receptors. For instance, a study reported changes in ligand binding to hippocampal kainate receptors. Another study found alterations in modulation of GABAA receptors by benzodiazepines and neurosteroids. Conclusions: These studies suggest that the effects of ethanol on brain ion channels may have a role in the pathophysiology of Alcohol-Related Neurodevelopmental Disorders and Fetal Alcohol Syndrome.

Early Postnatal Ethanol Exposure Has Long‐Term Effects on the Performance of Male Rats in a Delayed Matching‐to‐Place Task in the Morris Water Maze

There is concern that, in the absence of full-blown fetal alcohol syndrome, binge drinking during pregnancy might produce long-term cognitive deficits in offspring. Spatial working memory might be particularly vulnerable in this regard. This is the first study to address this issue in an animal model of binge exposure during the brain growth spurt using a delayed matching-to-place (DMTP) task in the Morris water maze. Infant male rats were gastrostomized and reared artificially from postnatal days (PD) 5 to 18. From PD 6 to 9 they were fed either 6.5 g x kg(-1) x d (-1) ethanol (EtOH) in a binge exposure model (BAC 302 mg/dl) or an isocaloric maltose-dextrin solution (MD). The study included a third suckled control group (SC) that was reared normally. The rats were tested on a series of problems in the DMTP task, first as juveniles (PD 35) and then twice again as adults. Each problem included an initial search trial and a subsequent test trial. The first two phases of testing used delays of either 0 sec or 60 sec between these two trials. The third phase increased this delay to 60 sec and 2 hr. In addition, the rats were tested on a cued task in the water maze. EtOH rats were impaired relative to controls in their ability to relocate the hidden platform on the second trial, which followed the search trial. In Phases 1 and 2, there was no differential effect of ethanol on performance across the 0-sec and 60-sec delay conditions. However, EtOH rats were more affected by the longer 2-hr delay in Phase 3. There were no group differences on the search trial, in swimming speed, or cued-task performance. These findings establish that binge exposure to ethanol during the brain growth spurt results in a long-lasting impairment on the DMTP performance of rats in the water maze.

Early Postnatal Ethanol Exposure Has Long-Term Effects on the Performance of Male Rats in a Delayed Matching-to-Place Task in the Morris Water Maze

Early Postnatal Ethanol Exposure Has Long-Term Effects on the Performance of Male Rats in a Delayed Matching-to-Place Task in the Morris Water Maze

Postnatal ethanol exposure blunts upregulation of GABAA receptor currents in Purkinje neurons

Recently, we found that early postnatal ethanol exposure inhibits the maturation of GABAA receptors (GABAARs) in developing medial septum/diagonal band (MS/DB) neurons, suggesting that these receptors may represent a target for ethanol related to fetal alcohol syndrome (FAS). To determine whether GABAARs on other neurons are also sensitive to a postnatal ethanol insult, postnatal day (PD) 4–9, rat pups were artificially reared and exposed to ethanol (4.5 g kg−1 day−1, 10.2% v/v). The pharmacological profile of acutely dissociated cerebellar Purkinje cell GABAARs from untreated, artificially reared controls and ethanol-treated animals was examined with conventional whole-cell patch clamp recordings during PD 12–16 (juveniles) and PD 25–35 (young adults). For untreated animals, GABA (0.3–100 μM) consistently induced inward Cl− currents in a concentration-dependent manner showing an age-related increase in maximum response without change in EC50 or slope value. Acute ethanol (100 mM) consistently inhibited 3 μM GABA currents (10–20%); positive modulators, pentobarbital (10 μM), midazolam (1 μM) and loreclezole (10 μM), consistently potentiated; the negative modulator, Zn2+ (30 μM), inhibited GABA currents across both juvenile and young adult groups. Loreclezole potentiation increased while Zn2+ inhibition decreased with age in untreated Purkinje neurons. Postnatal ethanol exposure (PD 4–9) decreased GABAAR maximum current density in young adult Purkinje cells but not in juvenile neurons. However, sensitivity to allosteric modulators did not change after ethanol. These data are consistent with the hypothesis that postnatal ethanol exposure during the brain growth spurt can disturb GABAAR development across the brain, although the mechanism(s) underlying this action remains to be determined.

Development of GABA A receptors on medial septum/diagonal band (MS/DB) neurons after postnatal ethanol exposure

The impact of `binge-like' ethanol exposure on postnatal days (PD) 4–9 was examined on development of γ-aminobutyric acid type A receptors (GABA AR) during the first month of life in the rat. Whole-cell patch-clamp recordings in acutely isolated medial septum/diagonal band (MS/DB) neurons were used to define effects of rapidly applied ethanol and other allosteric modulators on bicuculline-sensitive GABA currents. Three age groups were examined including `pups' (PD 4–10), `juveniles' (PD 11–16) and `young adults' (PD 25–35). In untreated neurons, maximum responses to GABA and the apparent GABA EC 50 increased ∼2-fold during the first month of life. Potentiation of GABA responses by pentobarbital, midazolam, and loreclezole all increased with age, while Zn 2+ inhibition declined. Initial inhibition by ethanol switched to potentiation of GABA responses during this time. In vivo, binge-like ethanol treatment (4.5 g kg −1 day −1 divided into two doses, 2 h apart on PD 4–9) reduced both the GABA maximal response and GABA EC 50 measured on PD 11–16. These measures returned to control levels by PD 25–35. After binge-like postnatal ethanol exposure, age-dependent loss of Zn 2+ inhibition of GABA responses was increased, while potentiating actions of in vitro ethanol were blocked. GABA AR modulation by other drugs was unaffected. These data suggest that early postnatal ethanol exposure disrupts the expected developmental pattern of GABA AR function in MS/DB neurons, an action that could contribute to neurobehavioral deficits associated with the fetal alcohol syndrome. Whether these changes are due to cellular damage, delayed gene expression or post-translational modification needs to be determined.