The measurement of 2,3-butanediol and 1,2-propanediol in "flushing" and "non-flushing" Japanese

Seven Japanese medical students, three "flushers" and four "non-flushers," were given 0.5 g ethanol/kg body weight PO in an attempt to assess whether elevated body acetaldehyde can account for 2,3-butanediol production in humans. Blood was taken from the anticubital vein immediately prior to, 30, 60, 90, and 120 min after ingestion of ethanol. No difference in the two groups was observed in 2,3-butanediol or in 1,2-propanediol. Measured 1,2-propanediol was in the normal range in both groups. No 2,3-butanediol was detected in any of the subjects.     

Dissociation between the locomotor and anxiolytic effects of acetaldehyde in the elevated plus-maze: Evidence that acetaldehyde is not involved in the anxiolytic effects of ethanol in mice

Acetaldehyde, the first product of ethanol metabolism, has been suggested to play a major role in many behavioral effects of ethanol. However, very few studies have directly tested the behavioral effects of the acute administration of acetaldehyde. In particular, the role of this metabolite in ethanol-induced anxiolytic effects has never been extensively tested. The aim of the present study was to characterize the anxiolytic effects of acetaldehyde in two strains of mice, C57BL/6J and CD1 mice with the elevated plus-maze procedure. The results show that acute injections of ethanol (1–2 g/kg) induced significant dose-dependent anxiolytic effects in both strains of mice. In contrast, acetaldehyde failed to produce any anxiolytic effect, although it induced a significant hypolocomotor effect at the highest doses. In an independent experiment, cyanamide, an aldehyde dehydrogenase inhibitor, prevented the locomotor stimulant effects of ethanol, although it failed to alter its anxiolytic effects. Together, the results of the present study indicate that acetaldehyde is not involved in ethanol-induced anxiolytic effects, although it may be involved in its sedative/hypolocomotor effects.     

Risk appraisal and endoscopic screening for esophageal squamous cell carcinoma in Japanese populations

Epidemiological studies have shown several strong predictors for selecting Japanese persons at high risk for esophageal squamous cell carcinoma (ESCC). (1) Alcohol consumption and tobacco smoking synergistically increase the risk, and a low intake of green and yellow vegetables or fruit and a low body mass index also increase the risk of ESCC. (2) The presence of esophageal distinct iodine-unstained lesions and melanosis are associated with an increased risk of ESCC. (3) The combination of alcohol consumption and inactive heterozygous aldehyde dehydrogenase-2 (ALDH2) and less-active homozygous alcohol dehydrogenase-1B (ADH1B) increases the risk of ESCC in a multiplicative fashion. (4) The results of a simple flushing questionnaire predict the ALDH2 phenotype with a high accuracy. (5) High mean corpuscular volume (MCV), which is induced by heavy drinking, high acetaldehyde exposure, heavy smoking, and poor nutrition, may be useful in identifying high-risk persons. Endoscopic screening with esophageal iodine staining in Japanese high-risk populations yields very high rates of early ESCC. Treatment of early ESCC by endoscopic mucosectomy has become a widespread practice in Japan and has succeeded in improving the outcome of this high-mortality cancer. New evidence concerning ALDH2/ADH1B/alcohol flushing/MCV-related cancer susceptibility has renewed interest in alcohol and acetaldehyde as important subjects for cancer research and has served as a powerful tool for cancer prevention and cancer screening of Japanese subjects. Review articles on this topic also appeared in the previous issue (Volume 4 Number 3). An editorial related to this article is available at .     

The total margin of exposure of ethanol and acetaldehyde for heavy drinkers consuming cider or vodka

Heavy drinkers in Scotland may consume 1600 g ethanol per week. Due to its low price, cider may be preferred over other beverages. Anecdotal evidence has linked cider to specific health hazards beyond other alcoholic beverages. To examine this hypothesis, nine apple and pear cider samples were chemically analysed for constituents and contaminants. None of the products exceeded regulatory or toxicological thresholds, but the regular occurrence of acetaldehyde in cider was detected. To provide a quantitative risk assessment, two collectives of exclusive drinkers of cider and vodka were compared and the intake of acetaldehyde was estimated using probabilistic Monte–Carlo type analysis. The cider consumers were found to ingest more than 200-times the amount of acetaldehyde consumed by vodka consumers. The margins of exposure (MOE) of acetaldehyde were 224 for the cider and over 220,000 for vodka consumers. However, if the effects of ethanol were considered in a cumulative assessment of the combined MOE, the effect of acetaldehyde was minor and the combined MOE for both groups was 0.3. We suggest that alcohol policy priority should be given on reducing ethanol intake by measures such as minimum pricing, rather than to focus on acetaldehyde.     

Does Acetaldehyde Mediate Ethanol Action in the Central Nervous System?

BACKGROUND: Some of the effects of ethanol in the central nervous system are due to changes in function of ligand-gated ion channels. Production of detectable amounts of acetaldehyde, a primary metabolite of ethanol, has been demonstrated in brain homogenates. The aim of this study was to determine whether central actions that are often attributed to ethanol may actually be mediated by acetaldehyde. METHODS: The effects of acetaldehyde (1-1000 microM) were tested by two-electrode voltage-clamp electrophysiology in Xenopus laevis oocytes expressing 10 different ligand-gated ion channel receptors [alpha1 glycine; alpha1beta2gamma2Sgamma-aminobutyric acid (GABA)A; rho1 GABAc; 5-hydroxytryptamine-3A; NR1a/NR2A NMDA; GluR1/GluR2 AMPA; GluR6/KA2 kainate; and alpha4beta2, alpha4beta4, and alpha2beta4 nicotinic-acetylcholine] and the G-protein-coupled inward rectifying potassium channel GIRK2. We also investigated the effect of acetaldehyde on the dopamine transporter (DAT), performing dopamine uptake assays in oocytes expressing DAT. RESULTS: Acetaldehyde (1 and 10 microM) significantly enhanced alpha1 glycine receptor-mediated currents. Acetaldehyde did not affect the function of any of the other receptors tested or the potassium currents measured in GIRK2 channels. Moreover, acetaldehyde did not alter the DAT-mediated dopamine uptake. CONCLUSIONS: Our results suggest a potential minor role for acetaldehyde in the glycine receptor-mediated effects of ethanol. Otherwise, acetaldehyde does not modulate function of the neuronal receptors tested in this study, in GIRK channels or DAT, when expressed recombinantly in Xenopus laevis oocytes.     

The ameliorating effect of Rosa roxburghii against ethanol-induced psychomotor alterations in rats

Background: Ethanol (EtOH) is one of the oldest recreational substances known to man, primarily taken because it induces a sense of well-being (euphoric effects) and relaxation (anxiolytic effects). EtOH use entails various negative consequences. Of particular interest are EtOH-induced psychomotor alterations, because of its immediate manifestation and adverse consequences. Rosa roxburghii (RR), a wild plant of Southwest China, has gained attention on account of its numerous beneficial effects on the immune, nervous, and cardiovascular systems. Objective: In the present study we assessed the effects of Rosa roxburghii (RR) on EtOH-induced psychomotor alterations in rats. Methods: Sprague Dawley rats were orally administered distilled water (control group) or ethanol (4?g/kg BW) (EtOH-group) to induce psychomotor alterations. RR extract (25, 50, and 100?mg/kg, p.o.) was administered 30?min before EtOH treatment (RR-group). EtOH-induced psychomotor alterations were evaluated in the open-field, accelerating rotarod, hanging wire, and cold swimming tests. Behavioral evaluation and hematological analysis (EtOH and acetaldehyde concentration) were done at 1, 2, 4 and 8 hours after EtOH administration. Results: The EtOH group showed psychomotor alterations as compared with the control group. These EtOH-induced psychomotor alterations were directly related to the rise in blood ethanol and acetaldehyde concentrations. Pre-treatment of RR significantly improved EtOH-induced psychomotor alterations on open-field, accelerating rotarod, hanging wire, and cold swimming tests. These improvements in psychomotor performance coincided with the decreased blood ethanol and acetaldehyde levels observed in the RR-treated group. Conclusion: These results suggest that RR has ameliorating effects against EtOH-induced psychomotor alterations.     

Stable Acetaldehyde Adducts: Structural Characterization of Acetaldehyde Adducts of Human Hemoglobin N-Terminal β-Globin Chain Peptides

Acetaldehyde is the first oxidation product of ethanol in vivo. Our earlier work showed that with sufficient acetaldehyde, five of the six possible sites of the peptide pentalysine were moddied as a Schiff base (Braun KP, et al: J Biol Chem 270:11263–11266, 1995). However, we were unable to deduce unequivocally which site was unmodified. Lysine residues, as well as the amine terminal valine residues, in hemoglobin have been implicated as target structures for acetaldehyde adducts resulting from ethanol consumption. Hemoglobin adducts of acetaldehyde have been used clinically as a marker of ethanol consumption, but the chemical nature of these adducts remains undefined. As part of our continuing structural characterization of acetaldehyde-protein adduct formation, we studied the peptides Val-His-Leu-Thr-Pro and Val-His-Leu-Thr-Pro-Val-Glu-Lys, from the amine terminus of the β-globin chain of hemoglobin, in vitro. Both peptides have at least one potential site for adduct formation. In the octapeptide, the N-terminal amine group of Val as well as the e-amine group of the lysine sidechain can potentially be modified by acetaldehyde. We used mass spectrometry, carbon-13 nuclear magnetic resonance, and Raman spectroscopy and characterized stable Schiff base acetaldehyde adducts of these two peptides at both reactive sites. The identification of stable Schiff base adducts with the N-terminal peptides of the β-chain of hemoglobin as well as with β-amino groups of lysine provides another possible means of monitoring ethanol consumption. The functional implications of these stable Schfl bases remains undefined.     

Production of Antibodies That Recognize the Heterogeneity of Immunoreactive Sites in Human Hemoglobin Chemically Modified by Acetaldehyde

Human hemoglobin (Hgb) was incubated with acetaldehyde under two different conditions: (a) in the presence of 250 mM acetaldehyde for 1 hr then reduced with 100 mM NaCNBH₃ for an additional 4 hr at room temperature; and (b) in the presence of 500 mM acetaldehyde for 10 days at room temperature and then reduced with 1 mM NaBH₄ for 1 hr. It was found that 44% and 27% of free amino groups in Hgb-acetaldehyde adduct (AA) remained unmodified when Hgb was treated under conditions (a) and (b), respectively. SDS-PAGE analysis revealed that the molecular weight of Hgb-AA(a) [Hgb modified under condition (a)] was slightly greater than that of unmodified Hgb and extensive protein cross-linking had occurred in Hgb-AA(b) [Hgb modified under condition (b)]. Electrophoresis on agarose gel showed the order of negative charge was Hgb-AA(b) > Hgb-AA(a) > unmodified Hgb. Polyclonal antibody raised in rabbits using keyhole limpet hemocyanin as the carrier protein modified by acetaldehyde under condition (a) [i.e., KLH-AA(a)] preferentially recognized Hgb-AA(a), whereas antibody raised using KLH-AA(b) as the immunogen recognized only Hgb-AA(b). In conclusion, antibodies raised with protein-AA antigens produced under different conditions recognize different epitopes.     

Cytotoxicity of Acetaldehyde‐Derived Advanced Glycation End‐Products (AA‐AGE) in Alcoholic‐Induced Neuronal Degeneration

Abstract : Background: The Maillard reaction that leads to the formation of advanced glycation end‐products (AGEs) plays an important role in the pathogenesis of angiopathy in diabetic patients, in aging and in neurodegenerative processes. We hypothesize that acetaldehyde (AA), one of the main metabolites of alcohol, may be involved in alcohol‐induced neurotoxicity in vivo by formation of AA‐derived AGEs (AA‐AGE) with brain proteins. Methods: AA‐AGE‐bovine serum albumin (BSA) and AA‐AGE‐rabbit serum albumin (RSA) were prepared as described previously. Antibody specific for AA‐AGE was isolated from rabbit antiserum by affinity chromatography. Primary cortical neuronal cell cultures were prepared as described previously. Results: Incubation of cortical neurons with AA‐AGE produced a dose‐dependent increase in neuronal cell‐death, and the neurotoxicity of AA‐AGE was neutralized by the addition of an anti‐AA‐AGE specific antibody, but not by anti‐N‐ethyllysine (NEL) antibody. The AA‐AGE epitope was detected in human brain of alcoholism. Conclusions: We propose that the structural epitope AA‐AGE is an important toxic moiety for neuronal cells in alcoholism.