Publications by authors named "Eduardo Karahanian"

Alcohol use disorder (AUD) is a public health problem characterized by a marked increment in systemic inflammation. In the last few years, it has been described as the role of alcohol in neuroinflammation affecting some aspects of neuronal function. Interestingly, inflammation is reduced with fenofibrate treatment, a PPARα agonist used to treat dyslipidemia.

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High ethanol consumption triggers neuroinflammation, implicated in sustaining chronic alcohol use. This inflammation boosts glutamate, prompting dopamine release in reward centers, driving prolonged drinking and relapse. Fibrate drugs, activating peroxisome proliferator-activated receptor alpha (PPAR-α), counteract neuroinflammation in other contexts, prompting investigation into their impact on ethanol-induced inflammation.

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A close communication exists between the microorganisms that live in the intestine and the brain, the so-called microbiota-gut-brain axis. This interaction occurs at different levels, such as the induction by bacteria of an inflammatory state in the intestine that produces (i) stimulation of the vagus nerve that conducts information to the brain, and (ii) the release of proinflammatory cytokines - such as TNF-α- to circulation, which can then be transported to the brain and trigger neuroinflammation. Ethanol-induced neuroinflammation is produced, in part, by the impairment of the epithelial barrier function of the intestine, since acetaldehyde generated in the gut from ethanol oxidation produces a disassembly of the tight junctions (TJ), which allows diffusion of bacterial components into the blood; these events trigger a systemic inflammatory response that crosses the blood-brain barrier and induce neuroinflammation.

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Short-chain fatty acids (SCFAs) are carboxylic acids produced as a result of gut microbial anaerobic fermentation. They activate signaling cascades, acting as ligands of G-protein-coupled receptors, such as GPR41, GPR43, and GPR109A, that can modulate the inflammatory response and increase the intestinal barrier integrity by enhancing the tight junction proteins functions. These junctions, located in the most apical zone of epithelial cells, control the diffusion of ions, macromolecules, and the entry of microorganisms from the intestinal lumen into the tissues.

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High-ethanol intake induces a neuroinflammatory response, which has been proposed as responsible for the maintenance of chronic ethanol consumption. Neuroinflammation decreases glutamate transporter (GLT-1) expression, increasing levels of glutamate that trigger dopamine release at the corticolimbic reward areas, driving long-term drinking behavior. The activation of peroxisome proliferator-activated receptor alpha (PPARα) by fibrates inhibits neuroinflammation, in models other than ethanol consumption.

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The concept that neuroinflammation induced by excessive alcohol intake in adolescence triggers brain mechanisms that perpetuate consumption has strengthened in recent years. The melanocortin system, composed of the melanocortin 4 receptor (MC4R) and its ligand α-melanocyte-stimulating hormone (α-MSH), has been implicated both in modulation of alcohol consumption and in ethanol-induced neuroinflammation decrease. Chronic alcohol consumption in adolescent rats causes a decrease in an α-MSH release by the hypothalamus, while the administration of synthetic agonists of MC4R causes a decrease in neuroinflammation and a decrease in voluntary alcohol consumption.

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Background: High ethanol intake induces a neuroinflammatory response resulting in the subsequent maintenance of chronic alcohol consumption. The melanocortin system plays a pivotal role in the modulation of alcohol consumption. Interestingly, it has been shown that the activation of melanocortin-4 receptor (MC4R) in the brain decreases the neuroinflammatory response in models of brain damage other than alcohol consumption, such as LPS-induced neuroinflammation, cerebral ischemia, glutamate excitotoxicity, and spinal cord injury.

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After ethanol consumption, disulfiram increases blood-acetaldehyde levels, generating an aversive reaction that deters alcohol drinking. Given the major secondary effects of disulfiram, finding other effective drugs to reduce alcohol consumption in individuals with alcohol-use-disorder is highly desirable. It has been reported that administering fenofibrate to high-drinking rats increases hepatic catalase levels and blood acetaldehyde after administering ethanol and a 60-70% inhibition of voluntary alcohol intake.

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Studies reviewed show that lentiviral gene therapy directed either at inhibiting the synthesis of brain acetaldehyde generated from ethanol or at degrading brain acetaldehyde fully prevent ethanol intake by rats bred for their high alcohol preference. However, after animals have chronically consumed alcohol, the above gene therapy did not inhibit alcohol intake, indicating that in the chronic ethanol intake condition brain acetaldehyde is no longer the compound that generates the continued alcohol reinforcement. Oxidative stress and neuroinflammation generated by chronic ethanol intake are strongly associated with the perpetuation of alcohol consumption and alcohol relapse "binge drinking".

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Excessive alcohol intake induces an inflammatory response in the brain, via TNFα, TLR4 and NF-κB signaling pathways. It has been proposed that neuroinflammation would play a very important role in the development of alcohol addiction. In addition to stimulating the synthesis of inflammatory mediators such as IL-6, IL-1β and TNFα, NF-κB is capable of reducing the anti-inflammatory activity of PPARα and PPARγ.

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We have previously shown that the administration of fenofibrate to high-drinker UChB rats markedly reduces voluntary ethanol intake. Fenofibrate is a peroxisome proliferator-activated receptor alpha (PPARα) agonist, which induces the proliferation of peroxisomes in the liver, leading to increases in catalase levels that result in acetaldehyde accumulation at aversive levels in the blood when animals consume ethanol. In these new studies, we aimed to investigate if the effect of fenofibrate on ethanol intake is produced exclusively in the liver (increasing catalase and systemic levels of acetaldehyde) or there might be additional effects at central level.

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Alcohol dependence causes physical, social, and moral harms and currently represents an important public health concern. According to the World Health Organization (WHO), alcoholism is the third leading cause of death worldwide, after tobacco consumption and hypertension. Recent epidemiologic studies have shown a growing trend in alcohol abuse among adolescents, characterized by the consumption of large doses of alcohol over a short time period.

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This review article addresses the biological factors that influence: (i) the of alcohol intake; (ii) the of chronic alcohol intake; and (iii) drinking behavior in animals bred for their high-ethanol intake. Data from several rat strains/lines strongly suggest that catalase-mediated brain oxidation of ethanol into acetaldehyde is an absolute requirement (up 80%-95%) for rats to display ethanol's reinforcing effects and to initiate chronic ethanol intake. Acetaldehyde binds non-enzymatically to dopamine forming salsolinol, a compound that is self-administered.

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Pantoea agglomerans LMAE-2 was isolated from seabed sediment moderately contaminated with Cu(2+) Here, we report its draft genome sequence, which has a size of 4.98 Mb. The presence of cop genes related with copper homeostasis in its genome may explain the resistance and strengthen its potential for use as bioremediation agent.

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This review analyzes literature that describes the behavioral effects of 2 metabolites of ethanol (EtOH): acetaldehyde and salsolinol (a condensation product of acetaldehyde and dopamine) generated in the brain. These metabolites are self-administered into specific brain areas by animals, showing strong reinforcing effects. A wealth of evidence shows that EtOH, a drug consumed to attain millimolar concentrations, generates brain metabolites that are reinforcing at micromolar and nanomolar concentrations.

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The administration of disulfiram raises blood acetaldehyde levels when ethanol is ingested, leading to an aversion to alcohol. This study was aimed at assessing the effect of fenofibrate on voluntary ethanol ingestion in rats. Fenofibrate reduces blood triglyceride levels by increasing fatty acid oxidation by liver peroxisomes, along with an increase in the activity of catalase, which can oxidize ethanol to acetaldehyde.

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Previous studies suggest that acetaldehyde generated from ethanol in the brain is reinforcing. The present studies tested the feasibility of achieving a long-term reduction of chronic and post-deprivation binge ethanol drinking by a single administration into the brain ventral tegmental area (VTA) of a lentiviral vector that codes for aldehyde dehydrogenase-2 (ALDH2), which degrades acetaldehyde. The ALDH2 gene coding vector or a control lentiviral vector were microinjected into the VTA of rats bred for their alcohol preference.

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The histones are essential basic proteins intimately involved in most DNA-templated processes. Thus, their purification and fractionation for analysis and their use for in vitro chromatin transactions are of fundamental importance for understanding their role in chromatin structure and regulation of DNA functions. Here are described three new protocols for histone isolation from undisturbed whole cells.

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Ethanol is metabolized into acetaldehyde mainly by the action of alcohol dehydrogenase in the liver, while mainly by the action of catalase in the brain. Aldehyde dehydrogenase-2 metabolizes acetaldehyde into acetate in both organs. Gene specific modifications reviewed here show that an increased liver generation of acetaldehyde (by transduction of a gene coding for a high-activity liver alcohol dehydrogenase ADH1(*)B2) leads to increased blood acetaldehyde levels and aversion to ethanol in animals.

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Background: Animals that have chronically consumed alcohol and are subsequently deprived of it markedly increase their intake above basal levels when access to alcohol is reinstated. Such an effect, termed the alcohol deprivation effect (ADE), has been proposed to reflect (i) an obsessive-compulsive behavior, (ii) craving, or (iii) an increased reinforcing value of ethanol (EtOH). It has been reported that acetaldehyde, a highly reinforcing metabolite of EtOH, is generated in the brain by the action of catalase.

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Background: In animal models of continuous alcohol self-administration, in which physical dependence does not constitute the major factor of ethanol intake, 2 factors likely contribute to the perpetuation of alcohol self-administration: (i) the rewarding effects of ethanol and (ii) the contextual conditioning cues that exist along with the process of self-administration. Present studies are aimed at understanding the relative contribution of these factors on the perpetuation of heavy alcohol self-administration, as an indication of relapse.

Methods: Wistar-derived UChB high ethanol drinker rats were allowed access to 10% ethanol and water on a 24-hour basis.

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Background:  While the molecular entity responsible for the rewarding effects of virtually all drugs of abuse is known, that for ethanol remains uncertain. Some lines of evidence suggest that the rewarding effects of alcohol are mediated not by ethanol per se but by acetaldehyde generated by catalase in the brain. However, the lack of specific inhibitors of catalase has not allowed strong conclusions to be drawn about its role on the rewarding properties of ethanol.

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Microcins are low-molecular-weight proteins secreted by certain bacteria that act by limiting the growth of other bacteria that share the same ecological niche. In the present work, the previous microcin 24 system was resequenced.We detected three nucleotide differences in the microcin-coding gene that partially change the amino acid sequence.

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