Effects of ethanol on glucose transporter expression in cultured hippocampal neurons

Initial study on quantitative electroencephalographic analysis of bioelectrical activity of the brain of children with fetal alcohol spectrum disorders (FASD) without epilepsy

Fetal alcohol spectrum disorders (FASD) are spectrum of neurodevelopmental conditions associated with prenatal alcohol exposure. The FASD manifests mostly with facial dysmorphism, prenatal and postnatal growth retardation, and selected birth defects (including central nervous system defects). Unrecognized and untreated FASD leads to severe disability in adulthood. The diagnosis of FASD is based on clinical criteria and neither biomarkers nor imaging tests can be used in order to confirm the diagnosis. The quantitative electroencephalography (QEEG) is a type of EEG analysis, which involves the use of mathematical algorithms, and which has brought new possibilities of EEG signal evaluation, among the other things-the analysis of a specific frequency band. The main objective of this study was to identify characteristic patterns in QEEG among individuals affected with FASD. This study was of a pilot prospective study character with experimental group consisting of patients with newly diagnosed FASD and of the control group consisting of children with gastroenterological issues. The EEG recordings of both groups were obtained, than analyzed using a commercial QEEG module. As a results we were able to establish the dominance of the alpha rhythm over the beta rhythm in FASD-participants compared to those from the control group, mostly in frontal and temporal regions. Second important finding is an increased theta/beta ratio among patients with FASD. These findings are consistent with the current knowledge on the pathological processes resulting from the prenatal alcohol exposure. The obtained results and conclusions were promising, however, further research is necessary (and planned) in order to validate the use of QEEG tools in FASD diagnostics.

Murine Models for the Study of Fetal Alcohol Spectrum Disorders: An Overview

Prenatal alcohol exposure is associated to different physical, behavioral, cognitive, and neurological impairments collectively known as fetal alcohol spectrum disorder. The underlying mechanisms of ethanol toxicity are not completely understood. Experimental studies during human pregnancy to identify new diagnostic biomarkers are difficult to carry out beyond genetic or epigenetic analyses in biological matrices. Therefore, animal models are a useful tool to study the teratogenic effects of alcohol on the central nervous system and analyze the benefits of promising therapies. Animal models of alcohol spectrum disorder allow the analysis of key variables such as amount, timing and frequency of ethanol consumption to describe the harmful effects of prenatal alcohol exposure. In this review, we aim to synthetize neurodevelopmental disabilities in rodent fetal alcohol spectrum disorder phenotypes, considering facial dysmorphology and fetal growth restriction. We examine the different neurodevelopmental stages based on the most consistently implicated epigenetic mechanisms, cell types and molecular pathways, and assess the advantages and disadvantages of murine models in the study of fetal alcohol spectrum disorder, the different routes of alcohol administration, and alcohol consumption patterns applied to rodents. Finally, we analyze a wide range of phenotypic features to identify fetal alcohol spectrum disorder phenotypes in murine models, exploring facial dysmorphology, neurodevelopmental deficits, and growth restriction, as well as the methodologies used to evaluate behavioral and anatomical alterations produced by prenatal alcohol exposure in rodents.

Functional Connectivity and Metabolic Alterations in Medial Prefrontal Cortex in a Rat Model of Fetal Alcohol Spectrum Disorder: A Resting-State Functional Magnetic Resonance Imaging and in vivo Proton Magnetic Resonance Spectroscopy Study

Prenatal ethanol exposure alters brain structure, functional connectivity, and behavior in humans and rats. Behavioral changes include deficits in executive function, which requires cooperative activity between the frontal cortices and other brain regions. In this study, we analyzed the functional connectivity and neurochemical levels of the prefrontal cortex (PFC) using resting-state functional magnetic resonance imaging (rsfMRI) and proton magnetic resonance spectroscopy (1H-MRS) in ethanol-exposed (Eth) and control (Ctr) rats. Pregnant Long-Evans rats were fed a liquid diet containing ethanol (2.1-6.46% v/v ethanol) from gestational days 6 to 21 (Eth). Ctr animals received an isocaloric, isonutritive liquid diet. In young adulthood, male and female offspring underwent in vivo MRI using a 7.0-Tesla system. 1H-MRS from the PFC and whole brain rsfMRI were obtained on the animals. Seed-based functional connectivity analysis was performed with seeds placed in the PFC, matching the voxel of MRS. Male, but not female, Eth rats showed less functional connectivity between PFC and dorsal striatum than Ctr animals. In Eth males glucose levels were significantly lower, and in Eth females lower levels of phosphorylcholine but an increased gamma-aminobutyric acid/glutamate ratio were observed in the PFC compared with Ctr animals. Prenatal ethanol alters brain metabolism and functional connectivity of the PFC in a sex-dependent manner.

Glucose Transporters at the Blood-Brain Barrier: Function, Regulation and Gateways for Drug Delivery

Glucose transporters (GLUTs) at the blood-brain barrier maintain the continuous high glucose and energy demands of the brain. They also act as therapeutic targets and provide routes of entry for drug delivery to the brain and central nervous system for treatment of neurological and neurovascular conditions and brain tumours. This article first describes the distribution, function and regulation of glucose transporters at the blood-brain barrier, the major ones being the sodium-independent facilitative transporters GLUT1 and GLUT3. Other GLUTs and sodium-dependent transporters (SGLTs) have also been identified at lower levels and under various physiological conditions. It then considers the effects on glucose transporter expression and distribution of hypoglycemia and hyperglycemia associated with diabetes and oxygen/glucose deprivation associated with cerebral ischemia. A reduction in glucose transporters at the blood-brain barrier that occurs before the onset of the main pathophysiological changes and symptoms of Alzheimer's disease is a potential causative effect in the vascular hypothesis of the disease. Mutations in glucose transporters, notably those identified in GLUT1 deficiency syndrome, and some recreational drug compounds also alter the expression and/or activity of glucose transporters at the blood-brain barrier. Approaches for drug delivery across the blood-brain barrier include the pro-drug strategy whereby drug molecules are conjugated to glucose transporter substrates or encapsulated in nano-enabled delivery systems (e.g. liposomes, micelles, nanoparticles) that are functionalised to target glucose transporters. Finally, the continuous development of blood-brain barrier in vitro models is important for studying glucose transporter function, effects of disease conditions and interactions with drugs and xenobiotics.

Ethanol affects differentiation-related pathways and suppresses Wnt signaling protein expression in human neural stem cells

BACKGROUND

Prenatal exposure of the fetus to ethanol (EtOH) can be teratogenic. We previously showed that EtOH alters the cell fate of human neural stem cells (NSC). As Wnt signaling plays an important role in fetal brain development, we hypothesized that EtOH suppresses Wnt signaling protein expression in differentiating NSC and thereby contributes to fetal alcohol spectrum disorder.

METHODS

NSC isolated from fetal human brains were cultured in mitogenic media to induce neurospheres, which were dissociated into single-cell suspensions and used for all experiments. Equal numbers of NSC were cultured on lysine/laminin-coated plates for 96 hours in differentiating media containing 0, 20, or 100 mM EtOH. Total mRNA was isolated from samples containing 0 or 100 mM EtOH and changes in expression of 263 genes associated with neurogenesis and NSC differentiation were determined by Oligo GEArray technology. The biological impact of gene changes was estimated using a systems biology approach with pathway express software and KEGG database. Based on the pathways identified, expression of Wnt proteins (Wnt3a and Wnt5a), Wnt-receptor complex proteins (p-LRP6, LRP6, DVL2, and DVL3), Wnt antagonist Naked-2 (NKD-2), and downstream Wnt proteins (β-catenin, Tyr-p-GSK3β, Ser-p-GSK3β) were analyzed by Western blot.

RESULTS

Of the 263 genes examined, the expressions of 22 genes in differentiating NSC were either upwardly or downwardly affected by EtOH. These genes are associated with 5 pathways/cellular processes: axon guidance; hedgehog signaling; TGF-β signaling; cell adhesion molecules; and Wnt signaling. When compared to controls, EtOH, at both 20 and 100 mM concentrations, suppressed the expression of Wnt3a and Wnt5a, receptor complex proteins p-LRP6, LRP6 and DVL2, and cytoplasmic proteins Ser-p-GSK3β and β-catenin. Expression of NKD-2 and DVL3 remained unchanged and the expression of active Tyr-p-GSK3β increased significantly.

CONCLUSIONS

EtOH can significantly alter neural differentiation pathway-related gene expression and suppress Wnt signaling proteins in differentiating human NSC.

Ethanol impaired neuronal migration is associated with reduced aspartyl-asparaginyl-beta-hydroxylase expression

Cerebellar hypoplasia in fetal alcohol spectrum disorders (FASD) is associated with inhibition of insulin and insulin-like growth factor (IGF) signaling in the brain. Aspartyl (asparaginyl)-beta-hydroxylase (AAH) is a mediator of neuronal motility, and stimulated by insulin and IGF activation of PI3 kinase-Akt, or inhibition of GSK-3beta. Since ethanol inhibits PI3 Kinase-Akt and increases GSK-3beta activity in brain, we examined the effects of ethanol and GSK-3beta on AAH expression and directional motility in neuronal cells. Control and ethanol-exposed (100 mM x 48 h) human PNET2 cerebellar neuronal cells were stimulated with IGF-1 and used to measure AAH expression and directional motility. Molecular and biochemical approaches were used to characterize GSK-3beta regulation of AAH and neuronal motility. Ethanol reduced IGF-1 stimulated AAH protein expression and directional motility without inhibiting AAH's mRNA. Further analysis revealed that: (1) AAH protein could be phosphorylated by GSK-3beta; (2) high levels of GSK-3beta activity decreased AAH protein; (3) inhibition of GSK-3beta and/or global Caspases increased AAH protein; (4) AAH protein was relatively more phosphorylated in ethanol-treated compared with control cells; and (5) chemical inhibition of GSK-3beta and/or global Caspases partially rescued ethanol-impaired AAH protein expression and motility. Ethanol-impaired neuronal migration is associated with reduced IGF-I stimulated AAH protein expression. This effect may be mediated by increased GSK-3beta phosphorylation and Caspase degradation of AAH. Therapeutic strategies to rectify CNS developmental abnormalities in FASD should target factors underlying the ethanol-associated increases in GSK-3beta and Caspase activation, e.g. IGF resistance and increased oxidative stress.

GLYCOSYLATION IS ALTERED BY ETHANOL IN RAT HIPPOCAMPAL CULTURED NEURONS

AIMS

Glycoproteins, such as adhesion molecules and growth factors, participate in the regulation of nervous system development. Ethanol affects the synthesis, intracellular transport, distribution, and secretion of N-glycoproteins in different cell types, including astrocytes and hepatocytes, suggesting alterations in the glycosylation process. We analysed the effect of exposure to low doses of ethanol (30 mm, 7 days) on glycosylation in cultured hippocampal neurons.

METHODS

Neurons were incubated for short (5 min) and long (90 min) periods with the radioactively labelled carbohydrate precursors 2-deoxy-glucose, N-acetyl-D-mannosamine and mannose. The uptake and metabolism of these precursors, as well as the radioactivity distribution in protein gels, were analysed. The levels of the glucose transporters GLUT1 and GLUT3 were also determined.

RESULTS

Ethanol exposure reduces the synthesis of proteins, DNA and RNA and decreased the uptake of mannose, but not of 2-deoxy-glucose and N-acetyl-D-mannosamine, and it increased the protein levels of both glucose transporters. Moreover, it altered the carbohydrate moiety of several proteins. Finally, alcohol treatment results in an increment of cell surface glycoconjugates containing terminal non-reduced mannose.

CONCLUSIONS

Alcohol-induced alterations in glycosylation of proteins in neurons could be a key mechanism involved in the teratogenic effects of alcohol exposure on brain development.

Seizures, ataxia, developmental delay and the general paediatrician: glucose transporter 1 deficiency syndrome

AIM

Glucose transporter 1 deficiency syndrome (GLUT1-DS) is an important condition for the general paediatrician's differential armamentarium. We describe a case series of eight patients in order to raise awareness of this treatable neurometabolic condition. The diagnosis of GLUT1-DS is suggested by a decreased absolute cerebrospinal fluid (CSF) glucose value (<2.2 mmol/L) or lowered CSF: plasma glucose ratio (<0.4).

METHODS

This is a review of eight Queensland patients with GLUT1-DS. The clinical presentation, clinical course, laboratory investigations and treatment outcomes are discussed.

RESULTS

The clinical features noted in our patient cohort include combinations of ataxia, developmental delay and a severe seizure disorder that is refractory to anticonvulsant medications. Seizures are the most common clinical manifestation and may be exacerbated by phenobarbitone. The paired CSF: plasma glucose results ranged from 0.2 to 0.39 (normal <0.6) with an average of 0.33. 3-O-Methyl-D-Glucose uptake and GLUT1 Genotyping analysis have been performed on five patients thus far. Rapid and impressive seizure control was observed in 100% of our patients once the ketogenic diet was instituted, with half of the cohort being able to wean completely from anticonvulsants.

CONCLUSION

Children presenting with a clinical phenotype consisting of a refractory seizure disorder, ataxia and developmental delay should prompt the consideration of Glucose transporter 1 deficiency syndrome. While the diagnostic test of lumbar puncture is an invasive manoeuvre, the diagnosis provides a viable treatment option, the ketogenic diet. GLUT1-DS displays clinical heterogeneity, but the value of early diagnosis and treatment is demonstrated by our patient cohort.

The neurodevelopmental consequences of prenatal alcohol exposure

During pregnancy, ingestion of alcohol, a known teratogen, can cause harm to the fetus. Prenatal alcohol exposure is one of the leading causes of birth defects, developmental disorders, and mental retardation in children. The fetal central nervous system is particularly vulnerable to alcohol; this vulnerability contributes to many of the long-term disabilities and disorders seen in individuals with prenatal alcohol exposure. Diagnoses associated with prenatal alcohol exposure include fetal alcohol syndrome (FAS), partial fetal alcohol syndrome, fetal alcohol effects, alcohol-related neurodevelopmental disorder, and alcohol-related birth defects. Once diagnosed, early intervention improves the long-term outcome of affected children. Without documentation of maternal alcohol use, a diagnosis, and consequently treatment, is often difficult to attain. It is imperative that nurses, physicians, and other healthcare providers become comfortable with obtaining a history of, and providing anticipatory guidance and counseling about, alcohol use.

Glut-1 deficiency syndrome: clinical, genetic, and therapeutic aspects

Impaired glucose transport across the blood-brain barrier results in Glut-1 deficiency syndrome (Glut-1 DS, OMIM 606777), characterized by infantile seizures, developmental delay, acquired microcephaly, spasticity, ataxia, and hypoglycorrhachia. We studied 16 new Glut-1 deficiency syndrome patients focusing on clinical and laboratory features, molecular genetics, genotype-phenotype correlation, and treatment. These patients were classified phenotypically into three groups. The mean cerebrospinal fluid glucose concentration was 33.1 +/- 4.9mg/dl equal to 37% of the simultaneous blood glucose concentration. The mean cerebrospinal fluid lactate concentration was 1.0 +/- 0.3mM, which was less than the normal mean value of 1.63mM. The mean V(max) for the 3-O-methyl-D-glucose uptake into erythrocytes was 996 fmol/10(6) red blood cells per second, significantly less (54 +/- 11%; t test, p < 0.05) than the mean control value of 1,847. The mean Km value for the patient group (1.4 +/- 0.5mM) was similar to the control group (1.7 +/- 0.5mM; t test, p > 0.05). We identified 16 rearrangements, including seven missense, one nonsense, one insertion, and seven deletion mutations. Fourteen were novel mutations. There were no obvious correlations between phenotype, genotype, or biochemical measures. The ketogenic diet produced good seizure control.

Metabolic effects of ethanol on primary cell cultures of rat skeletal muscle

Individuals who have consumed alcohol chronically accumulate glycogen in their skeletal muscles. Changes in the energy balance caused by alcohol consumption might lead to alcoholic myopathy. Experimental models used in the past, such as with skeletal muscle biopsy samples of alcohol-dependent individuals or in animal models, do not distinguish between direct effects and indirect effects (i.e., alterations to the nervous or endocrine system) of alcohol. In the current study, we evaluated the direct effect of ethanol on skeletal muscle glycogen concentrations and related glycolytic pathways. We measured the changes in metabolite concentrations and enzyme activities of carbohydrate metabolism in primary cell cultures of rat skeletal muscle exposed to ethanol for two periods. The concentrations of glycolytic metabolites and the activities of several enzymes that regulate glucose and glycogen metabolism were measured. After a short exposure to ethanol (6 h), glucose metabolism slowed. After 48 h of exposure, glycogen accumulation was observed.

Ethanol-induced decrease of the expression of glucose transport protein (Glut3) in the central nervous system as a predisposing condition to apoptosis: the effect of age

We measured the effect of chronic ethanol administration on the expression of Glut3 in the cerebellum and hippocampus of adult and old rats. Glut3 expression significantly decreased in aging, in ethanol-treated rats vs. age-matched controls, and in adult- vs. old ethanol-treated rats. These findings lend consistent support to the hypothesis that disturbances of glucose metabolism due to ethanol may constitute an unfavorable condition predisposing to neuronal death.

Microarray analysis of mouse brain gene expression following acute ethanol treatment

Alterations in gene expression are thought to help mediate certain effects of alcohol in the brain. We have analyzed the expression of approximately 24,000 genes using oligonucleotide microarrays to examine the brain expression profiles in two strains of inbred mice, C57BL/6J and DBA/2J, following exposure to an acute dose of ethanol. Our screen identified 61 genes responding to the ethanol treatment beyond a 1.5-fold threshold, with 46 genes altered in both mouse strains and 15 altered in only one strain. Approximately 25% of the genes were selected for confirmation by reverse transcriptase polymerase chain reaction with an 87% success rate. The genes identified have roles in cell signaling, gene regulation, and homeostasis/stress response. Although some of the genes were previously known to be ethanol responsive, we have for the most part identified novel genes involved in the acute murine brain response to ethanol. Such genes have the potential to represent candidate genes in the search to elucidate the molecular pathways mediating ethanol's effects in the brain.

Reversible infantile hypoglycorrhachia: possible transient disturbance in glucose transport?

Facilitated glucose transporter isoform 1 deficiency syndrome (GLUT1 DS), caused by impaired GLUT1-mediated glucose transport into the brain, is characterized by hypoglycorrhachia. The defect in the facilitative glucose transporter isoform 1 (GLUT1) can be confirmed by functional, quantitative, and molecular analyses. Diagnostic difficulties arise when these analyses are normal and hypoglycorrhachia remains unexplained. Three infants presenting with seizures and hypoglycorrhachia at 2, 4, and 6 weeks of age, which suggests GLUT1 deficiency syndrome, are reported. The seizures responded to a ketogenic diet in Patients 1 and 3 and phenobarbitone in Patient 2. Repeated GLUT1 analyses were normal. When treatment was discontinued, all patients remained seizure-free and developed normally. Subsequent lumbar punctures showed the return to normoglycorrhachia. We conclude that these cases might represent a transient disturbance in GLUT1-mediated glucose transport. The biomolecular basis for this clinical observation remains unknown. Though no treatment is required, clinical follow-up and repeated lumbar punctures are necessary to distinguish this benign condition from the original GLUT1 deficiency syndrome.

Ethanol impairs insulin-stimulated neuronal survival in the developing brain: role of PTEN phosphatase

Gestational exposure to ethanol causes fetal alcohol syndrome, which is associated with cerebellar hypoplasia. Previous in vitro studies demonstrated ethanol-impaired neuronal survival with reduced signaling through the insulin receptor (IRbeta). We examined insulin signaling in an experimental rat model of chronic gestational exposure to ethanol in which the pups exhibited striking cerebellar hypoplasia with increased apoptosis. Immunoprecipitation and Western blot analyses detected reduced levels of tyrosyl-phosphorylated IRbeta, tyrosyl-phosphorylated insulin receptor substrate-1 (IRS-1), and p85-associated IRS-1 but no alterations in IRbeta, IRS-1, or p85 protein expression in cerebellar tissue from ethanol-exposed pups. In addition, ethanol exposure significantly reduced the levels of total phosphoinositol 3-kinase, Akt kinase, phospho-BAD (inactive), and glyceraldehyde-3-phosphate dehydrogenase and increased the levels of glycogen synthase kinase-3 activity, activated BAD, phosphatase and tensin homolog deleted in chromosome 10 (PTEN) protein, and PTEN phosphatase activity in cerebellar tissue. Cerebellar neurons isolated from ethanol-exposed pups had reduced levels of insulin-stimulated phosphoinositol 3-kinase and Akt kinase activities and reduced insulin inhibition of PTEN and glycogen synthase kinase-3 activity. The results demonstrate that cerebellar hypoplasia produced by chronic gestational exposure to ethanol is associated with impaired survival signaling through insulin-regulated pathways, including failure to suppress PTEN function.

Ethanol impairs monosaccharide uptake and glycosylation in cultured rat astrocytes

Astrocyte and glial-neuron interactions have a critical role in brain development, which is partially mediated by glycoproteins, including adhesion molecules and growth factors. Ethanol affects the synthesis, intracellular transport, subcellular distribution and secretion of these glycoproteins, suggesting alterations in glycosylation. We analyzed the effect of long-term exposure to low doses of ethanol (30 mm) on glycosylation process in growing cultured astrocytes in vitro. Cells were incubated for short (5 min) and long (90 min) periods with several radioactively labeled carbohydrate precursors. The uptake, kinetics and metabolism of these precursors, as well as the radioactivity distribution in protein gels were analyzed. The levels of GLUT1 and mannosidase II were also determined. Ethanol increased the uptake of monosaccharides and the protein levels of GLUT1 but decreased those of mannosidase II. It altered the carbohydrate moiety of proteins and increased cell surface glycoproteins containing terminal non-reduced mannose. These results indicate that ethanol impairs glycosylation in rat astrocytes, thus disrupting brain development.

Glucose transporters and glucose utilization in rat brain after acute ethanol administration

In the normal adult brain, glucose provides 90% of the energy requirements as well as substrate for nucleic acid and lipid synthesis. In the present study, effects of ethanol on glucose transporters (GLUT) and glucose utilization were examined in rat brain. Male Sprague-Dawley rats weighing 250-300 gms were given either ethanol 3 gm/kg BW or saline i.p. 4 hrs prior to the animal sacrifice and removal of the cerebral cortical tissue. The cortical plasma membranes analyzed by cytochalasin B binding assay showed a decrease in GLUT number but not in GLUT affinity in the ethanol treated rats as compared to the control rats. The estimated Ro values were 70 +/- 8.9 Vs 91 +/- 8.9 pmoles/mg protein (p < 0.05 N=4) and the estimated Kd values were 0.37 +/- 0.03 and 0.28 +/- 0.05 microM (p: NS) in ethanol and control experiments respectively. Immunoblots of purified cerebral plasma membranes and low density microsomal fraction showed 17% and 71% decrease for GLUTI and 54% and 21% (p<0.05 or less; n=6) for GLUT3 respectively in ethanol treated rats than in control animals. Immunofluoresence studies also showed reduction of GLUT1 immunoreactively in choroid plexus and cortical microvessels of ethanol treated rats as compared to control rats. The effect of ethanol on regional cerebral metabolic rates for glucose (CMR(Glc)) was studied using [6-(14)C] glucose and showed statistically insignificant decrease in brain glucose utilization. These data suggest that ethanol in-vivo decrease GLUT number and protein content in rat cerebral cortex.

Gene expression of glucose transporters and glycolytic enzymes in the CNS of rats behaviorally dependent on ethanol

The steady-state levels of messenger RNA (mRNA) of the glucose transporters 1 and 3 and the glycolytic enzymes hexokinase, phosphofructokinase, glyceraldehyde-3-phosphate dehydrogenase and pyruvate dehydrogenase were measured in up to seven brain regions of the rat in a recently developed animal model of 'behavioral dependence' on ethanol. Irreversible behavioral dependence, including loss of control, was induced by offering the rats the choice between ethanol and water over a 9-month period (Group A). This group was compared with a group given the choice between ethanol and water for only 2 months (not yet behaviorally dependent, Group B), a group forced to consume ethanol as sole fluid over a 9-month period (not behaviorally dependent, Group C) and ethanol-naive control rats. All groups were sacrificed 1 month after ethanol withdrawal. The mRNA concentrations of both neuronal glucose transporter 3 and the key glycolytic enzymes phosphofructokinase and pyruvate dehydrogenase were significantly reduced in the hippocampi of the rats behaviorally dependent on ethanol (Group A). No significant changes were seen in any of the remaining brain regions (e.g., cortical areas, limbic forebrain, amygdala, midbrain) in Group A, or in any brain area at all in Groups B and C. The results show that chronic consumption of ethanol in a free-choice situation may impair neuronal glucose uptake and glycolytic flux. This effect is manifested exclusively in the hippocampus and is specifically related to the development of behavioral dependence, since it was not found after forced administration of large amounts of ethanol (Group C).

Fine structure of hippocampal dendrites in the dentate fascia of LS/SS-mice after chronic ethanol treatment

1. The effect of ethanol and its withdrawal on the dendritic microtubules in the dentate fascia of male mice was studied in the ethanol-sensitive, long-sleep (LS) line and the ethanol-insensitive, short-sleep (SS) line. 2. Both mouse lines were treated with a liquid ethanol diet. Dendrites in the dentate molecular layer (DML) of the right hippocampus were examined. 3. They revealed marked changes in microtubule density as compared with the controls. While the microtubule density in LS mice was significantly reduced by 15% and 18% in the middle and distal third of the DML, respectively, in SS mice the reduction (by 12%) took place in the distal third only. During withdrawal a recovery of the microtubule density has been observed in both lines.