Search

Background: Among some (e.g., DBA/2J or D2) but not all (C57BL/6J or B6) inbred strains of mice, ethanol has a marked psychostimulant effect. Intercrosses formed from the D2 and B6 strains have been used to detect quantitative trait loci (QTLs) for this phenotype. The major QTL is found at the mid-region of chromosome 2 (Demarest et al., 1999). This QTL has also been detected in heterogeneous stock mice (Demarest et al., 2001). A potential candidate gene in this region is Cas1, which codes for catalase. The current studies were conducted to determine (a) if there was difference in the open reading frame (ORF) of Cas1 between the D2 and B6 strains; (b) if a difference was found, was it likely that the difference had functional effects; and (c) if it could be established that Cas1 meets the criteria for QTL to gene. Methods: The open reading frame (ORF) of Cas1 was sequenced in both the D2 and B6 mouse strains. A single polymorphism was found between the strains (see below); the strain distribution pattern for this polymorphism was determined in the 36 strains of the B6XD2 (BXD) recombinant inbred (RI) series. These data were used to map the position of Cas1 as described by Cudmore et al. (1999). Results: The only difference between the D2 and B6 strains in the coding region was found at #349, G->A. This will result in a difference in the amino acid sequence between the strains at amino acid #117-alanine is found in the D2 strain while threonine is found in the B6 strain. The RI strain distribution pattern for this polymorphism was used to determine the relative placement of Cas1. The estimate suggests that Cas1 is flanked by D2Mit12 and D2Mit43 and relative to D2Mit94 (which was set at 47 cM), Cas1 is located at approximately 57 cM, confirming previous estimates (see http://www.jax.org). Conclusions: Pharmacological data (Correa et al., 2001) strongly support the idea that Cas1 meets the criteria for QTL to gene. However, based on the mapping data, Cas1 is clearly not included in the QTL for heterogeneous stock mice. Finally, other genetic data suggest that the polymorphism is not sufficient to generate the QTL. [ABSTRACT FROM AUTHOR]

Background : This study was designed to investigate the relationship between the ethanol-oxidizing capacity of the brain, accumulation of acetaldehyde, and ethanol-induced hypnosis in animals in vivo. Methods: Randomly outbred albino rats were treated with ethanol, and the duration of ethanol-induced loss of the righting response (sleep time) was measured. They were killed 2 weeks later (without further in vivo administration of ethanol), and brain homogenates were prepared to measure the accumulation of acetaldehyde from ethanol added in vitro. In a similar way, we determined the sleep time and, 5 days later, the rates of acetaldehyde accumulation in brains of heterogeneous mice. Results: Significant correlations between the duration of ethanol-induced sleep and acetaldehyde accumulation in vitro were found. The Km value of the process of acetaldehyde accumulation was lower in long-sleeping, as compared with short-sleeping, rats. A similar result was also obtained in genetically heterogeneous mice. Animals with a longer duration of ethanol-induced sleep had a higher level of the accumulation of ethanol-derived acetaldehyde in brain homogenates, as compared with the short-sleeping mice. Rats and mice with the intermediate duration of ethanol-induced sleep had an intermediate value of acetaldehyde accumulation in brain homogenates. There was no correlation between brain catalase activity and ethanol-induced loss of the righting response in either the rats or the mice. Conclusions: This study is a direct demonstration of the positive correlation between ethanol-derived acetaldehyde accumulation in vitro in the brain and a central (behavioral) effect of alcohol in outbred rats and mice in vivo. [ABSTRACT FROM AUTHOR]

Background : Recent advances in the field of acetaldehyde (AcH) research have raised the need for a comprehensive review on the role of AcH in the actions of alcohol. This update is an attempt to summarize the available AcH research. Methods : The descriptive part of this article covers not only recent research but also the development of the field. Special emphasis is placed on mechanistic analyses, new hypotheses, and conclusions. Results : Elevated AcH during alcohol intoxication causes alcohol sensitivity, which involves vasodilation associated with increased skin temperature, subjective feelings of hotness and facial flushing, increased heart and respiration rate, lowered blood pressure, sensation of dry mouth or throat associated with bronchoconstriction and allergy reactions, nausea and headache, and also reinforcing reactions like euphoria. These effects seem to involve catecholamine, opiate peptide, prostaglandin, histamine, and/or kinin mechanisms. The contribution of AcH to the pathological consequences of chronic alcohol intake is well established for different forms of cancer in the digestive tract and the upper airways. AcH seems to play a role in the etiology of liver cirrhosis. AcH may have a role in other pathological developments, which include brain damage, cardiomyopathy, pancreatitis, and fetal alcohol syndrome. AcH creates both unpleasant aversive reactions that protect against excessive alcohol drinking and euphoric sensations that may reinforce alcohol drinking. The protective effect of AcH may be used in future treatments that involve gene therapy with or without liver transplantation. Conclusions : AcH plays a role in most of the actions of alcohol. The individual variability in these AcH-mediated actions will depend on the genetic polymorphism, not only for the alcohol and AcH-metabolizing enzymes but also for the target sites for AcH actions. The subtle balance between aversive and reinforcing, protecting and promoting factors will determine the overall behavioral and pathological developments. [ABSTRACT FROM AUTHOR]

Background: PC12 pheochromocytoma cells were used as a model to study the effect of long-term ethanol exposure on signal transduction systems. In PC12 cells, the agonist bradykinin stimulates a phospholipase C specific for inositol-containing phospholipids and a phospholipase D specific for phosphatidylcholine. Methods: PC12 cells were grown in monolayer and cultured in the presence and absence of 1% ethanol for 5 days. After this period, bradykinin-stimulated phospholipase C and D were measured. The effect of long-term ethanol on the bradykinin-mediated activation of mitogen-activated protein (MAP) kinase was also measured. Results: In cells exposed to 1% ethanol for 5 days, bradykinin-stimulated phospholipase D was greatly attenuated, whereas bradykinin-stimulated phospholipase C was not altered. The tyrosine kinase inhibitor, genistein, blocked the bradykinin-mediated activation of phospholipase D but did not affect the stimulation of phospholipase C. However, long-term ethanol treatment did not attenuate the ability of bradykinin to activate MAP kinase, which suggests that ethanol did not have a general effect on all tyrosine kinase pathways. Conclusions: Ethanol has a differential effect on signal transduction in PC12 cells. Activation of phospholipase D may be mediated by a kinase, whereas the activation of phospholipase C is probably mediated by the guanine nucleotide binding protein, Gq. Because of these differences in activation mechanism, the pathways may adapt differently to long-term exposure to ethanol. [ABSTRACT FROM AUTHOR]

It was found that the accumulation of acetaldehyde produced from 50 mM ethanol in rat brain homogenates takes place in all major brain regions. The velocity varied between 3.5 to 7.1 nmol/mg of protein/hr. The rate increased in the following orderbrain hemispheres, striatum, brainstem, hypothalamus, and cerebellum. Significant regional differences in this process were found in the initial period of incubation (5 min), acetaldehyde accumulation was maximal in the brain hemispheres; but, in the 30- to 60-min period, it became significantly higher in the cerebellum. Inhibition of this process by the catalase inhibitor, 3-amino-1,2,4-triazole (8 mM), was minimal in the brainstem (27%) and maximal (57%) in the cerebellum, despite nearly complete inhibition of catalase. This would indicate that processes other than catalase activity must contribute to acetaldehyde accumulation. [ABSTRACT FROM AUTHOR]

Fetal ethanol (E) exposure has well documented deleterious effects on brain development, yet it is uncertain if the neurotoxicity of maternal E consumption is generated by E itself, by its primary metabolite acetaldehyde (AcHO), or both. The current studies present evidence that homogenates of immature rat brains can generate AcHO via a catalase (CAT)-mediated reaction and that AcHO may be produced in vivo by this system. Homogenates of day 19 fetal rat brain were incubated with E (50 mM). When incubated with CAT inhibitors (sodium azide or 3-aminotriazole), AcHO formation was blocked, whereas neither the alcohol dehydrogenase inhibitor, 4-methylpyratole, nor P-450 inhibitors decreased AcHO production. Three hours after one oral dose of E (4 g/kg) to a pregnant dam (gestation day 19), AcHO levels in fetal brain increased to 14.28 ± 1.82 nM/g tissue. Baseline CAT activity in day 19 fetal brains was 4.5 times adult values ( p < 0.05). Western blot analysis determined that CAT protein level in the day 19 fetal brain exceeded that in adult brain by 2.5 times. One hour after a single dose of E, CAT activity in day 19 fetal brain increased by 8.2 units/mg protein. In 5-day-old neonatal brains during the 'third trimester' brain growth spurt, baseline CAT activity was twice the adult values ( p < 0.05) and a 2-day in vivo E regimen increased AcHO levels to four times the control values, with a concomitant 1.7-fold increase in CAT activity. This was prevented by administration of a CAT inhibitor (3-amino-1,2,4-triazole). Immunohistochemical staining of neonatal brains exposed to E illustrated the presence of acetaldehyde-protein adducts. We conclude that AcHO is likely produced in rat fetal and neonatal brain via CAT-mediated oxidation of E. This phenomenon may be an important factor in the neurotoxic effects of in utero E exposure. [ABSTRACT FROM AUTHOR]

To evaluate the possible role of catalase in gastric ethanol metabolism in rats, we studied acetaldehyde formation from ethanol by gastric mucosal homogenate under various in vitro conditions. Homogenized rat gastric mucosa produced significant amounts of acetaldehyde in a time and ethanol concentration-dependent manner, even in the absence of added NAD. Both acetaldehyde formation and catalase activity peaked around the physiological pH, whereas alcohol dehydrogenase (ADH) activity was in that pH range low and reached peak values only at a higher pH of 9 to 10. Catalase inhibitors sodium azide (SA) and 3-amino-1,2,4-triazole (3-AT) had little effect on ADH activity but markedly decreased catalase activity and acetaldehyde formation (1 mM of SA to 56 ± 13% of control, 5 mM of 3-AT to 67 ± 3% of control; mean ± SE). 4-Methylpyrazole decreased ADH activity significantly, but did not affect acetaldehyde formation. Heating of the homogenate at 60°C for 5 min decreased ADH activity only slightly, but totally abolished catalase activity and reduced acetaldehyde formation to 39 ± 3% of control. Addition of a H2O2 generating system [β- d(+)-glucose + glucose oxidase] increased acetaldehyde formation in a concentration-dependent manner up to 8-fold of the control value. Our results strongly suggest that, in addition to ADH, catalase may play a significant role in gastric ethanol metabolism in rats. [ABSTRACT FROM AUTHOR]