PubMed Health⌕ Search

Biomedical subjects

C Guerri

Publications and source records attributed to C Guerri.

At least 91 records · Page 5Linked to original sources
PubMed1983

Chronic ethanol treatment affects synaptosomal membrane-bound enzymes.

A progressive increase in activity of some brain membrane-bound enzymes is shown after 2 and 4 weeks of ethanol administration. After 4 weeks the activities in brain homogenate of (Na+, K+) ATPase, Ca++ ATPase, 5'-nucleotidase, acetylcholinesterase and adenylate cyclase increased 150, 200, 140, 125 and 129 percent, respectively. Arrhenius plots of synaptosomal (Na+, K+) ATPase and acetylcholinesterase from alcohol-treated rats showed a lower transition temperature than control rats after two weeks, and this changed to a higher transition temperature after 4 and 8 weeks. Also, when ethanol was added in vitro to the control membranes, the transition temperature was lowered. However, if the alcohol was added to the membranes from alcohol-treated animals, the transition temperature was lowered to a value similar to that of controls. Fluorescence studies with l-anilinonaphthalene-8-sulfonate (ANS) demonstrate that ethanol induces a decrease in the fluorescence of ANS bound to brain synaptic membranes. This decrease in fluorescence is less than when these membranes are derived from chronically ethanol-treated rats. Also, when the synaptosomal enzymes were exposed to exogenous agents such as detergents, the enzyme obtained from alcohol-treated rats was more stable than that from control rats. These findings indicate a protein conformation change, probably due to the alteration of the physical properties of membrane lipids following chronic ethanol administration. These findings also demonstrate that there is a resistance to the effect of ethanol in membranes of animals habituated to ethanol that may be related to the adaptative modifications that underlie tolerance to and physical dependence on alcohol.

5'-Nucleotidase↗
PubMed1982

Effect of lithium on synaptosomal brain enzymes.

During 7 days of lithium administration to rats, the levels of adenylate cyclase bound to brain synaptosomes decreased, while those of acetylcholinesterase increased. Both enzyme levels returned to their initial values after 1 month of treatment. Monoamine oxidase, which is bound to a mitochondrial membrane, was not affected by lithium treatment. Arrhenius plots of the brain synaptosomal enzymes (Na + K)ATPase and acetylcholinesterase from rats treated with LiCl for 7 or 30 days showed a lower transition temperature. Also, when these synaptosomal enzymes were exposed to such exogenous agents as detergents or alcohol, the reaction of the enzymes obtained from lithium treated rats was different than that of control rats. These effects disappeared after ceasing lithium administration for one week. These data indicate changes in the structure of brain membranes after lithium administration.

Acetylcholinesterase↗
PubMed1982

Effects of prenatal and postnatal exposure of rats to alcohol: changes in (Na+-K+) ATPase.

Maternal ethanol consumption produces a reduction in postnatal growth. We have studied especially changes of liver and brain. This reduction is more marked if the alcoholic offspring are maintained with their biological mothers than if they are kept with surrogate mothers. Rats exposed prenatally to alcohol show a marked accumulation of fat in the liver and a significant proliferation of liver endoplasmic reticulum. No change in the postnatal development of liver alcohol (ADH) and acetaldehyde dehydrogenases (ALDH) (high and low Km) is observed in offspring from alcoholic mothers, with the exception of slightly higher ALDH (low Km) for the offspring that remain with alcoholic mothers. The postnatal development of the liver (Na+-K+) ATPase is also similar in control and alcoholic groups. However, in the case of the enzyme from the brain, a lower ATPase activity is observed in the group derived from alcoholic mothers. Interestingly, at 20 days of postnatal period, an induction of the ATPase (from liver and brain) was observed when the group of offspring from alcoholic mothers were kept on an alcohol diet.

Alcohol Dehydrogenase↗
PubMed1981

Inhibition of protein synthesis in cell cultures by vanadate and in brain homogenates of rats fed vanadate.

Following the observation of polysome disaggregation by vanadate, when Neuro-2a cells were incubated with vanadate, incorporation of 3H-leucine into protein was markedly inhibited. The inhibition of protein synthesis was dependent on vanadate concentration and on time of incubation. Inhibition of cell growth was also observed. Simultaneous measurements on vanadate-treated cells showed decreased Na,K-ATPase activity. Rats given sodium vanadate as their sole drinking fluid also showed an inhibition of brain protein synthesis (18 and 20% after 30 and 60 days, respectively, of treatment). Possible implications of the inhibition of Na,K-ATPase and of protein synthesis by vanadate are discussed.

Animals↗
PubMed1980

Effect of ethanol on glutathione concentration in isolated hepatocytes.

1. Ethanol induces a decrease in GSH (reduced glutathione) concentration is isolated hepatocytes. Maximal effects appear at 20 mM-ethanol. The concentration-dependence of this decrease is paralleled by the concentration-dependence of the activity of alcohol dehydrogenase. 2. Pyrazole, a specific inhibitor of alcohol dehydrogenase, prevents the ethanol-induced GSH depletion. 3. Acetaldehyde, above 0.05 mM, also promotes a decrease in GSH concentration in hepatocytes. 4. Disulfiram (0.05 mM), an inhibitor of aldehyde dehydrogenase, potentiates the fall in GSH concentration caused by acetaldehyde. 5. The findings support the hypothesis that acetaldehyde is responsible for the depletion of GSH induced by ethanol. 6. Methionine prevents the effect of alcohol or acetaldehyde on GSH concentration in hepatocytes.

Acetaldehyde↗
PubMed1976

Protection against toxic effects of formaldehyde in vitro, and of methanol or formaldehyde in vivo, by subsequent administration of SH reagents.

Rapid and progressive inactivation in vitro of both alcohol dehydrogenase and aldehyde dehydrogenase by low concentrations of acetaldehyde or formaldehyde is illustrated. This inactivation can be prevented or reversed by glutathione or other SH reagents. Those effects led to investigations in vivo. Rats and mice were injected with concentrations that would result in death in approximately 10 h (methanol) and approximately 4 h (formaldehyde). When 2,3-dimercaptopropanol (BAL), cysteine, or mercaptoethanol was injected (10 min to 3 h) after administration of methanol or formaldehyde, approximately 70% of the animals survived indefinitely; the remaining 30% showed substantial increase in survival time. The findings indicate the possibility of using reagents such as BAL for human therapy and suggest that the toxicity of methanol and formaldehyde is due in part to effects other than acidosis.

Alcohol Oxidoreductases↗
PubMedDate not supplied

Acetaldehyde and alcohol levels in pregnant rats and their fetuses.

Alcohol and acetaldehyde blood levels were measured in chronic alcoholic pregnant rats and their fetuses at 15, 19 and 21 days of gestation. Similar ethanol concentrations were found in fetal and maternal blood in all gestation periods studied, however levels in amniotic fluid were higher than in mother's blood, especially in the early stages of gestation. Acetaldehyde concentrations were always lower in fetal than in maternal blood although increasing throughout gestation. The levels in fetal blood and amniotic fluid compared to maternal blood, were ca. 40, 50 and 70% at 15, 19 and 21 days of gestation, respectively; those for the placenta and fetal tissues were lower, i.e., 25, 40 and 50%. Similar alcohol and acetaldehyde ratios (fetus/mother's concentration) were obtained when pregnant non-alcoholic rats were administered cyanamide and ethanol (2 g/kg) at 11, 15, 19 and 21 days of gestation. These results demonstrate that ethanol freely crosses the placental barrier, but there is a concentration gradient of acetaldehyde between mother and fetus which varies with gestation age.

Acetaldehyde↗