Effects on glycosylation enzymes from membrane fractions, induced by chronic ethanol administration

Effect of Ethanol Treatment on Rate and Equilibrium Constants for [3H]Muscimol Binding to Rat Brain Membranes: Alteration of Two Affinity States of the GABAA Receptor

“…The mechanisms of action of ethanol are difficult to evaluate, because it acts at various levels . Its administration inhibits glycoprotein biosynthesis and secretion (Tuma and Sorrel, 1984), and it affects the physicochemical properties of membranes (Wood et al ., 1989), modifying the functional properties of membrane-bound proteins such as enzymes (Gil et al ., 1990), receptors, and transport systems (Michaelis, 1989) . In the brain, it alters neurotransmitter systems.…”

Effect of Chronic Ethanol Treatment on the γ‐Aminobutyric Acid‐Mediated Enhancement of [3H]Flunitrazepam Binding in Rat Cortex and Hippocampus

“…After weaning, 28-day-old male Wistar rats weighing 120-125 g were kept in a room at constant temperature (20-22°C) on a 12-h light/dark cycle, fed with A-04 rat chow (Panlab) containing 17% protein, 3% lipid, and 59% carbohydrate, and progressively given an aqueous ethanol solution (5-20%) as described by Gil-Martin et al (1990). Control rats were pair fed, belonging to the same litter as the ethanol-treated rats, and growth curves were monitored along with the treatment (data not shown).…”

“…The molecular mechanisms of action of ethanol have proved difficult to assess because it is known that this drug can operate at various levels. Its administration inhibits protein biosynthesis and glycoprotein secretion (Mailliard et al, 1984; Tuma and Son-ell, 1984), and it also has diverse effects on the physicochemical properties of biological membranes (Chin and Goldstein, 1977;Wood et al, 1989), leading to alterations in the functional properties of membrane-bound proteins, such as receptors (Anokhima et al, 1983;Crews et al, 1989), transport systems (Michaelis, 1989), and enzymes (Gil-Martin et al, 1990). Chronic exposure of animals to ethanol produces tolerance and physical dependence, although the molecular mechanisms involved are poorly understood.…”

N-Acetyl-β-Hexosaminidase Activity and Isoenzymes in Human Gastric Adenocarcinoma

“…Assays of ß-hexosaminidase activity from tumor and control tissues were carried out in parallel and consisted of the spectrophotometric determination at 400 nm of enzymatically released p-nitrophenol from both p-nitrophenyl-N-acetyl-ß-D-glucosaminide and pnitrophenyl-N-acetyl-ß-D-galactosaminide substrates [42]. Briefly, the incubation mixtures contained, in 1 ml, 100 Ìmol citrate buffer (pH 4.5), 0.8 Ìmol of adequate p-nitrophenyl-glycoside derivative substrate and 100 Ìl of protein preparation (containing 0.1-0.2 mg protein).…”