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C Guerri

Publications and source records attributed to C Guerri.

At least 37 records · Page 2Linked to original sources
PubMed1997

Alcohol, astroglia, and brain development.

Glial cells constitute one of the most common cell types in the brain. They play critical roles in central nervous system (CNS) development. Recent evidence demonstrates that glial cells are profoundly affected by prenatal alcohol exposure, suggesting that alterations in these cells may participate in CNS abnormalities associated with ethanol-induced teratogenesis. In vivo studies show that prenatal exposure to alcohol hampers myelinogenesis and is associated with neuroglial heterotopias and abnormal astrogliogenesis. Studies using primary cultures of rat cortical astrocytes show that ethanol affects DNA, RNA, and protein synthesis, decreases the number of mitotic cells, alters the content and distribution of several cytoskeletal proteins including the astroglial marker, glial fibrillary acidic protein (GFAP), and the levels of plasma-membrane glycoproteins, reduces the capacity of astrocytes to secrete growth factors, and induces oxidative stress. Furthermore, ethanol exposure during early embryogenesis alters the normal development of radial glia cells (the main astrocytic precursors), delays the onset of GFAP expression, and decreases mRNA GFAP levels in fetal and postnatal brains and in radial glia and astrocytes in primary culture. Recent evidence suggests that ethanol interferes with the transcription process of GFAP, thus leading to a reduction in GFAP-gene expression during astrogliogenesis. However, brief exposure of rats to high levels of ethanol during the neonatal period (the period of astrocyte differentiation) causes a transient gliosis, with an increase in GFAP and its mRNA levels. These findings indicate that astroglial cells are an important target of ethanol toxicity during central nervous system (CNS) development.

Aging↗
PubMed1997

Ethanol exposure affects glial fibrillary acidic protein gene expression and transcription during rat brain development.

Exposure to ethanol during fetal development reduces the astroglial-specific marker glial fibrillary acidic protein (GFAP) and its mRNA levels in brains of fetal rats and in radial glia in primary culture, affecting the proliferation and differentiation of astrocytes. The objectives of this study were to evaluate the possible effect of ethanol on GFAP mRNA levels in astrocytes and to investigate the molecular mechanism(s) involved in ethanol-induced changes in GFAP expression by analyzing the GFAP transcription rate, GFAP mRNA stability, and GFAP DNA methylation. We show here that prenatal exposure to ethanol reduces significantly GFAP immunoreactivity and its mRNA levels in both astrocytes in primary culture and brains of pups from alcohol-fed mothers. Runoff experiments from nuclei of astrocytes indicate that ethanol exposure decreases GFAP transcription rate significantly and reduces GFAP mRNA stability slightly. DNA methylation analysis indicates that prenatal ethanol exposure induces a hypermethylated state of the GFAP DNA in fetal brains. Methylation-mediated repression of GFAP transcription could be a mechanism involved in ethanol-induced reduction of GFAP expression. Ethanol-induced alterations in GFAP expression and astroglial development may underlie the CNS dysfunctions observed after prenatal alcohol exposure.

Aging↗
PubMed1996

Glial fibrillary acidic protein expression in rat brain and in radial glia culture is delayed by prenatal ethanol exposure.

The alterations in astrocyte proliferation and differentiation induced by prenatal exposure to alcohol (PEA) suggest that ethanol exposure affects the radial glial cells, the main astrocytic precursors. We have investigated the effects of ethanol on the early stages of astrogliogenesis by analyzing the developmental pattern of vimentin and glial fibrillary acidic protein (GFAP) immunoreactivity and their mRNA levels during embryonic/fetal brain development and in radial glia in primary culture. GFAP appeared late in gestation and at day 5 of culture of radial glia, whereas GFAP mRNA was first detected on fetal day 15 and increased in content on fetal day 21. In contrast, the levels of vimentin and its mRNA were high at fetal day 15 but decreased on day 21. Alcohol exposure delays the appearance of GFAP and its mRNA and significantly decreases the GFAP expression in fetal brain and in primary culture of radial glia. In addition, some morphological alterations were observed in PEA glial cells in culture. These results demonstrate that astroglial precursor cells are damaged by prenatal exposure to ethanol and suggest that abnormalities in the astrogliogenesis may underlie the disruption in neuronal migration and other CNS alterations observed after prenatal ethanol exposure.

Animals↗
PubMed1996

Effects of chronic alcohol consumption on enzyme activities and active methionine absorption in the small intestine of pregnant rats.

The present study evaluates the effect of chronic alcohol intake on the intestinal transport of methionine during pregnancy. For this purpose, we have used an in vitro technique that allows measurement of the unidirectional influx of the amino acids across the brush-border membrane of the rat mid-jejunum, and the basolateral membrane enzyme Na+, K+-ATPase was also evaluated in the duodenum and jejunum. For chronic alcohol treatment, the rats were fed a liquid diet containing ethanol (36% of calories) or an isocaloric diet-(pair-fed control) for 5 weeks before and during pregnancy. Animals were killed at 21 days of gestation. Results from the kinetic analysis revealed that chronic ethanol treatment reduces the maximum transport (Jm) of methionine uptake when compared with controls. Further experiments performed in the presence and absence of sodium have shown that ethanol selectively inhibited Na+-dependent methionine transport. At the same time, this treatment significantly reduced the levels of Na+, K+-ATPase in ethanol-fed rats compared with the controls. Alterations in methionine intestinal transport in pregnant alcohol-fed rats may contribute to the ethanol-induced fetal growth abnormalities.

Animals↗
PubMed1995

Alcohol exposure during brain development reduces 3H-MK-801 binding and enhances metabotropic-glutamate receptor-stimulated phosphoinositide hydrolysis in rat hippocampus.

Glutamate receptors play important roles during brain development. We have investigated the effect of chronic maternal alcohol intake on the ontogenic profile of hippocampal glutamate receptor subtypes in their offspring. Binding of 3H-MK-801 to N-methyl-D-aspartate (NMDA) receptor was measured in isolated membranes from the hippocampus of the offspring of pair-fed control and alcohol-fed rats at different times during the postnatal life. Phosphatidylinositol triphosphate (PIP2) hydrolysis was also assayed to provide a measure of the possible effect of ethanol on the metabotropic glutamate receptor (mGluR). In pair-fed control rats, at postnatal day (PND) 3, the 3H-MK-801 binding represents 60% of adult values. Binding then rises to 170% at PND 11, and gradually decreases to adult levels. A transient overshoot in the mGluR-coupled PIP2 hydrolysis was also observed during postnatal development in rat hippocampus. Alcohol-exposed rats showed a similar pattern, but a significant decrease in the specific binding for NMDA receptor was observed on all the postnatal days analyzed. In addition, alcohol exposure significantly decreases the number of specific 3H-MK-801 binding sites, with no change in the affinity of the sites for 3H-MK-801. Moreover, this treatment enhanced the mGluR-activated PIP2 hydrolysis in hippocampus of alcohol-exposed rats. These results may contribute to an understanding of the toxic effects of ethanol on the developing central nervous system (CNS) and help explain the cognitive deficits associated with prenatal alcohol exposure.

Animals↗
PubMed1995

Study of surface carbohydrates on isolated Golgi subfractions by fluorescent-lectin binding and flow cytometry.

The Golgi complex is a functionally heterogeneous subcellular structure that plays a key role in the synthesis, maturation, and sorting of newly synthesized glycoproteins. Fluorescent lectins have been used extensively to analyze surface glycoproteins by flow cytometry in whole cells and more recently in isolated subcellular organelles, such as mitochondria and chloroplasts. We report here the use of several fluorescein-isothiocyanate-conjugated lectins to detect and quantify specific surface sugars by flow cytometry on isolated elements from purified cis and trans-Golgi fractions from rat liver. Our results show that this approach may be useful to study Golgi composition and function, since it may reveal the intensity of specific binding of different lectins to each Golgi fraction and the percentage of elements binding the lectins specifically. Thus we show here that Golgi elements appear homogeneous in mannose and fucose, whereas galactose and N-acetyl-glucosamine residues are more abundant in the trans-Golgi elements.

Animals↗
PubMed1995

Developmental pattern of GFAP and vimentin gene expression in rat brain and in radial glial cultures.

In the present study we analyze the events which occur during the early stages of astrogliogenesis by examining the pattern of both GFAP and vimentin gene expression and their corresponding immunoreactive proteins during rat brain development. This study was carried out "in vivo" (whole brain) and "in vitro" (primary culture of radial glia) using immunofluorescence, immunoblotting, and Northern blot analysis. Our results demonstrate that although GFAP immunostaining appeared late in gestation and at day 5 in radial glia cultures, GFAP mRNA expression was first detected, at very low levels, on fetal (F) day 15 and increased to F21. During postnatal development a striking increase in GFAP and its encoding messenger occurs. In contrast, the levels of vimentin and its mRNA expression were very high during the fetal stage (F15 to F21). Thereafter vimentin expression declined during postnatal (P) development until P21 and then remained constant at adult levels. In contrast, an increase in vimentin expression was observed in glial cells throughout the entire culture period. The biological significance of the developmental patterns of GFAP and vimentin expression in astroglial cells. during brain development is discussed.

Animals↗
PubMed1995

Variations in peroxisomal catalase of neonatal rat hepatocyte subpopulations. Effect of pre- and postnatal exposure to alcohol.

Alcohol consumption during pregnancy is teratogenic and induces severe alterations in hepatocytes. In the hepatocyte peroxisomal system, ethanol is converted in the presence of H2O2 to acetaldehyde and water. Therefore, peroxisomal catalase also acts as an antioxidant defence mechanism by removing H2O2 and preventing the formation of hydroxyl radicals in the cell. Alterations in peroxisomal catalase after pre- and pre+postnatal alcohol exposure were investigated in the rat. The effect of pre- and postnatal exposure to ethanol on hepatocyte subpopulations was analysed in isolated hepatocytes originating from periportal, intermediate and perivenous zones. Analysis of catalase revealed that the total activity and content of this enzyme were higher in 12-day-old cells than in cells from newborns and that this increment was more pronounced in treated cells. In controls, the amount of peroxisomal catalase increased mainly in periportal cells, whereas alcohol exposure induced a significant increase in the catalase of perivenous hepatocytes. We conclude that pre- and postnatal alcohol exposure mainly affects the perivenous hepatocyte peroxisomes and that the increase in peroxisomal catalase could constitute a defence mechanism against free radical generation induced by alcohol exposure during the perinatal period.

Animals↗
PubMed1995

Ethanol increases cytochrome P4502E1 and induces oxidative stress in astrocytes.

We demonstrate the presence of cytochrome P4502E1 (CYP2E1) in astrocytes in primary culture, its induction by ethanol, and the concomitant generation of free radical species. Double immunofluorescence using anti-CYP2E1 and anti-glial fibrillary acidic protein showed that CYP2E1 was distributed over the cytoplasm and processes, although labeling was more pronounced over the nuclear membrane. Immunogold labeling confirmed this pattern of distribution. Addition of 25 mM ethanol to the astrocyte culture medium for 14 days resulted in an increase in the CYP2E1 content, as determined by confocal microscopy and dot blot. In addition, ethanol induced a dose-dependent increase in the formation of reactive oxygen species that was partially prevented by incubating the astrocytes with anti-CYP2E1. Alcohol also induced a dose-dependent increase in malonaldehyde and hydroxynonenal formation and a depletion of the glutathione (GSH) content. These results suggest that ethanol induces oxidative damage in astrocytes, which could explain some of the toxic effects of ethanol on these cells, such as cytoskeletal alterations. This assumption is supported here by the fact that an increase in GSH content prevents the deleterious effects of alcohol on the cytoskeleton of astrocytes. These results suggest the importance of oxidative stress as a mechanism involved in alcohol-induced neural and brain damage.

Animals↗
PubMed1994

Prenatal exposure to ethanol induces changes in the nerve growth factor and its receptor in proliferating astrocytes in primary culture.

We have analyzed the effect of prenatal exposure to alcohol on the binding, internalization and secretion of NGF as well as on the content of the NGF receptor (NGFr) in cortical rat astrocytes in primary culture. Secretion of NGF was approximately 1.8-fold greater in 6-day control astrocytes than in 13-day cells. Intracellular content of NGF was very low. Astrocytes in 6-day cultures from control fetuses expressed a relatively large number of NGFr on the cell surface with a steady-state constant in the low nanomolar range. NGF was internalized by astrocytes at a slow rate. Prenatal exposure to ethanol induces a moderate increase in the number of NGFr on the cell surface as well as an increase in the intracellular pool of both NGF and NGFr which is accompanied by an important reduction in the secretion of this factor. We speculate that this decrease in NGF secretion could alter the neuronal migration pattern during development, resulting in the presence of ectopic neurons in the cortex.

Animals↗
PubMed1994

Ethanol-induced oxygen radical formation and lipid peroxidation in rat brain: effect of chronic alcohol consumption.

The effect of chronic and in vitro ethanol exposure on brain oxygen radical formation and lipid peroxidation was analyzed. Ethanol induces a dose-dependent increase in lipid peroxidation in brain homogenates. The peroxidative effects of alcohol seem to be related to both cytochrome P450 and the ethanol-inducible form of cytochrome P450 (CYP2E1), because preincubation with metyrapone (an inhibitor of cytochrome P450) or with an antibody against CYP2E1 abolished the ethanol-increased lipid peroxidation. Using the formation of dichlorofluorescein, we also demonstrated that both in vitro and chronic alcohol exposure significantly enhanced the formation of oxygen radical species in synaptosomes. Chronic alcohol treatment also leads to an induction of cytochrome P450 (230%), NADPH cytochrome c reductase (180%), NADPH oxidation (184%), and CYP2E1 in brain microsomes. In addition, this treatment produced a decrease in the GSH/GSSG ratio in brain and significantly enhanced the levels of superoxide dismutase and catalase activities. This mechanism could be involved in the toxic effects of ethanol on brain and membrane alterations occurring after chronic ethanol intake.

Alcoholism↗
PubMed1994

Nuclear calmodulin/62 kDa calmodulin-binding protein complexes in interphasic and mitotic cells.

We report here that a 62 kDa calmodulin-binding protein (p62), recently identified in the nucleus of rat hepatocytes, neurons and glial cells, consists of four polypeptides showing pI values between 5.9 and 6.1. By using a DNA-binding overlay assay we found that the two most basic of the p62 polypeptides bind both single- and double-stranded DNA. The intranuclear distribution of calmodulin and p62 was analysed in hepatocytes and astrocyte precursor cells, and in proliferating and differentiated astrocytes in primary cultures by immunogold-labeling methods. In non-dividing cells nuclear calmodulin was mostly localized in heterochromatin although it was also present in euchromatin and nucleoli. A similar pattern was observed for p62, with the difference that it was not located in nucleoli. p62/calmodulin complexes, mainly located over heterochromatin domains were also observed in interphasic cells. These complexes remained associated with the nuclear matrix after in situ sequential extraction with nucleases and high-salt containing buffers. In dividing cells, both calmodulin and p62 were found distributed over all the mitotic chromosomes but the p62/calmodulin aggregates were disrupted. These results suggest a role for calmodulin and p62 in the condensation of the chromatin.

Animals↗
PubMed1993

Developmental changes in the optic nerve related to ethanol consumption in pregnant rats: analysis of the ethanol-exposed optic nerve.

Visual impairment is one of the most common ophthalmic abnormalities in fetal alcohol syndrome. Pathologic changes in optic nerve development related to alcohol consumption could be involved in this dysfunction. In order to assess the consequences of pre- and postnatal exposure to alcohol on the developing optic nerve, we administered an ethanol-containing liquid diet (5% w/v) before and during gestation and throughout lactation to rats and their offspring. A group of control animals were kept on a pair-fed isocaloric diet. The optic nerves were obtained at key stages from fetuses (21 days of gestation) and pups (4, 7, 14, 21 and 28 postnatal days). Samples of the optic nerve cross-section, behind the eyeball, were processed for analysis of gliogenesis, myelinogenesis, axonal growth, and remodelling events, using light and electron microscopy. Qualitative, morphometric, and immunocytochemical analyses, alternatively using anti-GFAP and anti-MBP antibodies, were carried out. Optic nerve cross-sections from prenatal and postnatal alcohol-exposed rats showed a decrease in size. Ultrastructural alterations and retarded development in macroglial cells, optic axons, and myelin sheath were also observed. The most prominent abnormalities were: damage of cytoplasmic organelles and disorganization of cytoskeleton in astrocytes; a decrease in free ribosome density and nuclear membrane inclusions in oligodendrocytes; and fragmentation of lamellae, aberrant myelin sheaths and intralamellar inclusions in myelin. These findings suggest that alcohol abuse during pregnancy is teratogenic to the optic nerve and closely related to the altered visual function.

Abnormalities, Drug-Induced↗
PubMed1993

Flow cytometric analysis of concanavalin A binding to isolated Golgi fractions from rat liver.

Flow cytometry (FCM) has been used repeatedly to study lectin binding to whole cells. However, there are very few attempts to analyze glycoconjugates in isolated subcellular organelles. We have applied FCM to quantitate the specific binding of fluorescein-conjugated concanavalin A (FITC-Con A) to isolated cis and trans fractions of rat liver Golgi complex, the cell compartment involved in glycoprotein maturation and sorting. Our results show similar intensities of Con A-specific binding in the two fractions. Using this method we show a decreased FITC-Con A binding to both Golgi fractions in ethanol-treated rats, which is consistent to previous work on alcoholic effects on galactosyltransferase. The possible applications of this technique are discussed.

Alcohol Drinking↗