Understanding factors limiting hematopoietic cell transplantation for acute myeloid leukemia patients in Mexico: a comprehensive analysis.

Acute myeloid leukemia (AML) is the most frequent indication for allogeneic hematopoietic cell transplantation (alloHCT) worldwide; social and health system barriers limit its access. We performed an observational retrospective analysis in Mexico to analyze factors limiting alloHCT in fit patients with AML. With a median follow-up of 11.8 months, 301 patients were included, with a median age of 42; 33.5% were classified as adverse risk. Despite 215 patients (92.5%) achieving complete remission, only 103 (34%) had HLA-typing: 44.5% had a matched-sibling donor (MSD), 32% a haploidentical donor, and 23.5% had no donor. Only 23.5% of patients had an HCT consult; merely 36 underwent an HCT: 30 alloHCT, and six an autologous HCT. Age ≥ 60 years, HCT-CI score ≥ three, and the absence of a local transplant program negatively influenced HLA typing likelihood. Patients with an MSD had a higher alloHCT likelihood. The cumulative incidence of transplant (CIT) and relapse (CIR) at 6 and 12 months was 7.3% and 13.8%, 8.2% and 13%, respectively. A lack of HLA-typing was associated with a lower CIT (p < 0.001) and higher CIR (p = 0.033) (HR 11.72, CI 95% 4.39-31.27, p < 0.001), while the presence of an MSD was associated with a higher CIT (p = 0.002) (HR 4.22, CI 95% 1.89-9.44, p < 0.001). The main reasons hindering alloHCT are the lack of access to HLA-typing tests and the absence of an MSD. A national donor registry and improved HLA-typing accessibility are critical for increasing alloHCT access in Mexico.

The administration of Alda-1, an activator of ALDH2, inhibits relapse-like ethanol intake in female alcohol-preferring UChB rats.

AIMS: Alcohol relapse is a main limitation for the treatment of alcohol use disorders. Previous studies have shown that Alda-1, a pharmacological activator of ALDH2, inhibits both acquisition and chronic ethanol intake in rats; however, its effects on relapse-like ethanol intake are unknown. The aim of this study was to assess the effect of Alda-1 on post-deprivation and reaccess relapse-like ethanol intake in alcohol-preferring UChB rats. We also aimed to assess the possible mechanisms associated with the effects of Alda-1 by measuring the levels of glutamate transporter (GLT-1), oxidative stress and neuroinflammation markers in different regions of the mesocorticolimbic system. MAIN METHODS: In Experiment I, UChB female rats were exposed for 100 days to voluntary ethanol intake followed by 2-weeks of ethanol withdrawal and 1 week of ethanol reaccess. Alda-1 (25 mg/kg, intragastric, i.g) or vehicle was administered daily for 14 days during the withdrawal/re-access period. Experiment II was similar to Experiment I, but after the withdrawal period, ethanol re-access was not allowed, and Alda-1 was administered during the last week of withdrawal. At the end of both experiments, the levels of GLT-1, oxidative stress (GSH, MDA), and neuroinflammation markers (GFAP, Iba-1) were assessed in nucleus accumbens and/or hippocampus. KEY FINDINGS: The results showed that Alda-1 administration markedly blocked (90 %, p < 0.001) relapse-like ethanol intake in UChB rats. Alda-1 increased Iba-1 reactivity (microglial marker) in the NAc of ethanol-deprived rats. Alda-1 administration did not influence the levels of GLT-1, oxidative stress markers (MDA, GSH) or GFAP reactivity in the mesocorticolimbic system. SIGNIFICANCE: These preclinical findings support the use of activators of ALDH2, such as Alda-1, as a potential pharmacological strategy in the treatment of alcohol relapse.

Overexpression of wild type glycine alpha 1 subunit rescues ethanol sensitivity in accumbal receptors and reduces binge drinking in mice.

The nucleus accumbens (nAc) is a critical region in the brain reward system since it integrates abundant synaptic inputs contributing to the control of neuronal excitability in the circuit. The presence of inhibitory α1 glycine receptor (GlyRs) subunits, sensitive to ethanol, has been recently reported in accumbal neurons suggesting that they are protective against excessive binge consumption. In the present study, we used viral vectors (AAV) to overexpress mutant and WT α1 subunits in accumbal neurons in D1 Cre and α1 KI mice. Injection of a Cre-inducible AAV carrying an ethanol insensitive α1 subunit in D1 Cre neurons was unable to affect sensitivity to ethanol in GlyRs or affect ethanol drinking. On the other hand, using an AAV that transduced WT α1 GlyRs in GABAergic neurons in the nAc of high-ethanol consuming mice caused a reduction in ethanol intake as reflected by lowered drinking in the dark and reduced blood ethanol concentration. As expected, the AAV increased the glycine current density by 5-fold without changing the expression of GABAA receptors. Examination of the ethanol sensitivity in isolated accumbal neurons indicated that the GlyRs phenotype changed from an ethanol resistant to an ethanol sensitive type. These results support the conclusion that increased inhibition in the nAc can control excessive ethanol consumption and that selective targeting of GlyRs by pharmacotherapy might provide a mechanistic procedure to reduce ethanol binge.

UFR2709, an Antagonist of Nicotinic Acetylcholine Receptors, Delays the Acquisition and Reduces Long-Term Ethanol Intake in Alcohol-Preferring UChB Bibulous Rats.

Alcoholism is a worldwide public health problem with high economic cost and which affects health and social behavior. It is estimated that alcoholism kills 3 million people globally, while in Chile it is responsible for around 9 thousand deaths per year. Nicotinic acetylcholine receptors (nAChRs) are ligand-gated ion channels expressed in the central nervous system, and they were suggested to modulate the ethanol mechanism involved in abuse and dependence. Previous work demonstrated a short-term treatment with UFR2709, a nAChRs antagonist, which reduced ethanol intake using a two-bottle free-choice paradigm in University of Chile bibulous (UChB) rats. Here, we present evidence of the UFR2709 efficacy in reducing the acquisition and long-term ethanol consumption. Our results show that UFR2709 (2.5 mg/kg i.p.) reduces the seek behavior and ethanol intake, even when the drug administration was stopped, and induced a reduction in the overall ethanol intake by around 55%. Using naïve UChB bibulous rats, we demonstrate that UFR2709 could delay and reduce the genetically adaptive impulse to seek and drink ethanol and prevent its excessive intake.

Gene knockdown of HCN2 ion channels in the ventral tegmental area reduces ethanol consumption in alcohol preferring rats.

Background: Hyperpolarization-Activated Cyclic Nucleotide-Gated (HCN) ionic channels are known to play a key role in the control of neuron excitability and have been proposed as a molecular target of ethanol. Previous studies in rats have shown that gene-induced overexpression of the HCN2 channel in the ventral tegmental area (VTA) increases the rewarding effects of ethanol and its intake by the animals.Objective: The aim of this work was to study the effects of VTA HCN2 gene knockdown in the voluntary ethanol consumption of alcohol-preferring UChB rats.Methods: Two lentiviral vectors were generated; LV-siRNA-HCN2, coding for a siRNA that elicited >95% reduction of HCN2 protein levels in vitro, and a control vector coding for a scrambled siRNA sequence. Female UChB naïve rats (n = 14) were microinjected into the VTA with LV-siRNA-HCN2 or the scrambled control vector (n = 11). Four days after, animals were given a daily free access to 10% ethanol and water for 10 days.Results: Rats treated with the LV-siRNA-HCN2 vector showed a ~ 70% reduction (p < .001) in their ethanol preference and ethanol intake compared to control animals. No changes were observed in the total fluid intake of both groups. HCN2 levels in the VTA were measured by Western blot showing a reduction of 40% (p < .05) in the rats injected with LV-siRNA-HCN2, compared to control animals.Conclusion: These results show that knockdown of HCN2 ionic channels in the VTA of UChB rats markedly reduces their voluntary ethanol intake, supporting the idea that HCN2 channels may constitute a therapeutic target for alcohol use disorders.

Statins change the cytokine profile in Trypanosoma cruzi-infected U937 macrophages and murine cardiac tissue through Rho-associated kinases inhibition.

Introduction: Chronic Chagasic cardiomyopathy (CCC), caused by the protozoan Trypanosoma cruzi, is the most severe manifestation of Chagas disease.CCC is characterized by cardiac inflammation and fibrosis caused by a persistent inflammatory response. Following infection, macrophages secrete inflammatory mediators such as IL-1ß, IL-6, and TNF-α to control parasitemia. Although this response contains parasite infection, it causes damage to the heart tissue. Thus, the use of immunomodulators is a rational alternative to CCC. Rho-associated kinase (ROCK) 1 and 2 are RhoA-activated serine/threonine kinases that regulate the actomyosin cytoskeleton. Both ROCKs have been implicated in the polarization of macrophages towards an M1 (pro-inflammatory) phenotype. Statins are FDA-approved lipid-lowering drugs that reduce RhoA signaling by inhibiting geranylgeranyl pyrophosphate (GGPP) synthesis. This work aims to identify the effect of statins on U937 macrophage polarization and cardiac tissue inflammation and its relationship with ROCK activity during T. cruzi infection. Methods: PMA-induced, wild-type, GFP-, CA-ROCK1- and CA-ROCK2-expressing U937 macrophages were incubated with atorvastatin, or the inhibitors Y-27632, JSH-23, TAK-242, or C3 exoenzyme incubated with or without T. cruzi trypomastigotes for 30 min to evaluate the activity of ROCK and the M1 and M2 cytokine expression and secretion profiling. Also, ROCK activity was determined in T. cruzi-infected, BALB/c mice hearts. Results: In this study, we demonstrate for the first time in macrophages that incubation with T. cruzi leads to ROCK activation via the TLR4 pathway, which triggers NF-κB activation. Inhibition of ROCKs by Y-27632 prevents NF-κB activation and the expression and secretion of M1 markers, as does treatment with atorvastatin. Furthermore, we show that the effect of atorvastatin on the NF-kB pathway and cytokine secretion is mediated by ROCK. Finally, statin treatment decreased ROCK activation and expression, and the pro-inflammatory cytokine production, promoting anti-inflammatory cytokine expression in chronic chagasic mice hearts. Conclusion: These results suggest that the statin modulation of the inflammatory response due to ROCK inhibition is a potential pharmacological strategy to prevent cardiac inflammation in CCC.

UFR2709, a Nicotinic Acetylcholine Receptor Antagonist, Decreases Ethanol Intake in Alcohol-Preferring Rats.

Brain nicotinic acetylcholine receptors (nAChRs), a heterogeneous family of pentameric acetylcholine-gated cation channels, have been suggested as molecular targets for the treatment of alcohol abuse and dependence. Here, we examined the effect of the competitive nAChR antagonist UFR2709 on the alcohol consumption of high-alcohol-drinking UChB rats. UChB rats were given free access to ethanol for 24-h periods in a two-bottle free choice paradigm and their ethanol and water intake were measured. The animals were i.p. injected daily for 17 days with a 10, 5, 2.5, or 1 mg/kg dose of UFR2709. Potential confounding motor effects of UFR2709 were assessed by examining the locomotor activity of animals administered the highest dose of UR2709 tested (10 mg/kg i.p.). UFR2709 reduced ethanol consumption and ethanol preference and increased water consumption in a dose-dependent manner. The most effective dose of UFR2709 was 2.5 mg/kg, which induced a 56% reduction in alcohol consumption. Administration of UFR2709 did not affect the weight or locomotor activity of the rats, suggesting that its effects on alcohol consumption and preference were mediated by specific nAChRs.

Gene and cell therapy on the acquisition and relapse-like binge drinking in a model of alcoholism: translational options.

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". Mesenchymal stem cells, referred to as guardians of inflammation, release anti-inflammatory cytokines and antioxidant products. The intravenous delivery of human mesenchymal stem cells or the intranasal administration of mesenchymal stem cell-generated exosomes reverses both (i) alcohol-induced neuro-inflammation and (ii) oxidative stress, and greatly (iii) inhibits (80-90%) chronic alcohol intake and relapse binge-drinking. The therapeutic effect of mesenchymal stem cells is mediated by increased levels of the brain GLT-1 glutamate transporter, indicating that glutamate signaling is pivotal for alcohol relapse. Human mesenchymal stem cells and the products released by these cells may have translational value in the treatment of alcohol-use disorders.

Molecular modeling of salsolinol, a full Gi protein agonist of the µ-opioid receptor, within the receptor binding site.

(R/S)-Salsolinol is a full agonist of the µ-opioid receptor (µOR) Gi protein pathway via its (S)-enantiomer and is functionally selective as it does not promote ß-arrestin recruitment. Compared to (S)-salsolinol, the (R)-enantiomer is a less potent agonist of the Gi protein pathway. We have now studied the interactions of the salsolinol enantiomers docked in the binding pocket of the µOR to determine the molecular interactions that promote enantiomeric specificity and functional selectivity of (R/S)-salsolinol. Molecular dynamics simulations showed that (S)-salsolinol interacted with 8 of the 11 residues of the µOR binding site, enough to stabilize the molecule. (R)-Salsolinol showed higher mobility with fewer prevalent bonds. Hence, the methyl group bound to the (S)-stereogenic center promoted more favorable interactions in the µOR binding site than in the (R)-orientation. Because (S)-salsolinol is a small molecule (179.2 Da), it did not interact with residues implicated in the binding of larger morphinan agonists that are located toward the extracellular portion of the binding pocket: W3187.35 , I3227.39 , and Y3267.43 . Our results suggest that contact with residues which (S)-salsolinol interacts with are enough to elicit Gi protein activation, and possibly define a minimum set required by µOR ligands to promote activation of the Gi protein pathway.

Silencing brain catalase expression reduces ethanol intake in developmentally-lead-exposed rats.

Lead (Pb) is a developmental neurotoxicant. We have demonstrated that perinatally Pb-exposed rats consume more ethanol than their control counterparts, a response that seems to be mediated by catalase (CAT) and centrally-formed acetaldehyde, ethanol's first metabolite with attributed reinforcing effects in the brain. The present study sought to disrupt ethanol intake (2-10% ethanol v/v) in rats exposed to 220 ppm Pb or filtered water during gestation and lactation. Thus, to block brain CAT expression, a lentiviral vector coding for a shRNA against CAT (LV-antiCAT vector) was microinfused in the posterior ventral tegmental area (pVTA) either at the onset or towards the end of a chronic voluntary ethanol consumption test. At the end of the study, rats were euthanized and pVTA dissected to measure CAT expression by Western blot. The LV-antiCAT vector administration not only reversed, but also prevented the emergence of the elevated ethanol intake reported in the perinatally Pb-exposed animals, changes that were supported by a significant reduction in CAT expression in the pVTA. These results provide further evidence of the crucial role of this enzyme in the reinforcing properties of ethanol and in the impact of the perinatal Pb programming to challenging events later in life.

Erysodine, a competitive antagonist at neuronal nicotinic acetylcholine receptors, decreases ethanol consumption in alcohol-preferring UChB rats.

Alcohol abuse is a worldwide health problem with high economic costs to health systems. Emerging evidence suggests that modulation of brain nicotinic acetylcholine receptors (nAChRs) may be a therapeutic target for alcohol dependence. In this work, we assess the effectiveness of four doses of erysodine (1.5, 2.0, 4.0 or 8.0 mg/kg/day, i.p.), a competitive antagonist of nAChRs, on voluntary ethanol consumption behavior in alcohol-preferring UChB rats, administered during three consecutive days. Results show that erysodine administration produces a dose-dependent reduction in ethanol consumption respect to saline injection (control group). The highest doses of erysodine (4 and 8 mg/kg) reduce (45 and 66%, respectively) the ethanol intake during treatment period and first day of post-treatment compared to control group. While, the lowest doses of erysodine (1.5 and 2 mg/kg) only reduce ethanol intake during one day of treatment period. These effective reductions in ethanol intake were 23 and 29% for 1.5 and 2 mg/kg erysodine, respectively. Locomotor activity induced by a high dose of erysodine (10 mg/kg) was similar to those observed with saline injection in control rats, showing that the reduction in ethanol intake was not produced by hypolocomotor effect induced by erysodine. This is the first report showing that erysodine reduces ethanol intake in UChB rats in a dose-dependent manner. Our results highlight the role of nAChRs in the reward effects of ethanol and its modulation as a potentially effective pharmacological alternative for alcohol dependence treatment.

Fenofibrate Administration Reduces Alcohol and Saccharin Intake in Rats: Possible Effects at Peripheral and Central Levels.

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. High drinker rats (UChB) were allowed to voluntary drink 10% ethanol for 2 months. Afterward, a daily dose of fenofibrate (25, 50 or 100 mg/kg/day) or vehicle (as control) was administered orally for 14 days. Voluntary ethanol intake was recorded daily. After that time, animals were deprived of ethanol access for 24 h and administered with an oral dose of ethanol (1 g/kg) for acetaldehyde determination in blood. Fenofibrate reduced ethanol voluntary intake by 60%, in chronically drinking rats, at the three doses tested. Acetaldehyde in the blood rose up to between 80 µM and 100 µM. Considering the reduction of ethanol consumption, blood acetaldehyde levels and body weight evolution, the better results were obtained at a dose of 50 mg fenofibrate/kg/day. This dose of fenofibrate also reduced the voluntary intake of 0.2% saccharin by 35% and increased catalase levels 2.5-fold in the liver but showed no effects on catalase levels in the brain. To further study if fenofibrate administration changes the motivational properties of ethanol, a conditioned-place preference experiment was carried out. Animals treated with fenofibrate (50 mg/kg/day) did not develop ethanol-conditioned place preference (CPP).In an additional experiment, chronically ethanol-drinking rats underwent two cycles of ethanol deprivation/re-access, and fenofibrate (50 mg/kg/day) was given only in deprivation periods; under this paradigm, fenofibrate was also able to generate a prolonged (30 days) decreasing of ethanol consumption, suggesting some effect beyond the acetaldehyde-generated aversion. In summary, reduction of ethanol intake by fenofibrate appears to be a consequence of a combination of catalase induction in the liver and central pharmacological effects.

Acquisition, Maintenance and Relapse-Like Alcohol Drinking: Lessons from the UChB Rat Line.

This review article addresses the biological factors that influence: (i) the acquisition of alcohol intake; (ii) the maintenance of chronic alcohol intake; and (iii) alcohol relapse-like 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. In UChB rats, salsolinol: (a) generates marked sensitization to the motivational effects of ethanol; and (b) strongly promotes binge-like drinking. The specificity of salsolinol actions is shown by the finding that only the R-salsolinol enantiomer but not S-salsolinol accounted for the latter effects. Inhibition of brain acetaldehyde synthesis does not influence the maintenance of chronic ethanol intake. However, a prolonged ethanol withdrawal partly returns the requirement for acetaldehyde synthesis/levels both on chronic ethanol intake and on alcohol relapse-like drinking. Chronic ethanol intake, involving the action of lipopolysaccharide diffusing from the gut, and likely oxygen radical generated upon catechol/salsolinol oxidation, leads to oxidative stress and neuro-inflammation, known to potentiate each other. Data show that the administration of N-acetyl cysteine (NAC) a strong antioxidant inhibits chronic ethanol maintenance by 60%-70%, without inhibiting its initial intake. Intra-cerebroventricular administration of mesenchymal stem cells (MSCs), known to release anti-inflammatory cytokines, to elevate superoxide dismutase levels and to reverse ethanol-induced hippocampal injury and cognitive deficits, also inhibited chronic ethanol maintenance; further, relapse-like ethanol drinking was inhibited up to 85% for 40 days following intracerebral stem cell administration. Thus: (i) ethanol must be metabolized intracerebrally into acetaldehyde, and further into salsolinol, which appear responsible for promoting the acquisition of the early reinforcing effects of ethanol; (ii) acetaldehyde is not responsible for the maintenance of chronic ethanol intake, while other mechanisms are indicated; (iii) the systemic administration of NAC, a strong antioxidant markedly inhibits the maintenance of chronic ethanol intake; and (iv) the intra-cerebroventricular administration of anti-inflammatory and antioxidant MSCs inhibit both the maintenance of chronic ethanol intake and relapse-like drinking.

Beyond the "First Hit": Marked Inhibition by N-Acetyl Cysteine of Chronic Ethanol Intake But Not of Early Ethanol Intake. Parallel Effects on Ethanol-Induced Saccharin Motivation.

BACKGROUND: A number of studies have shown that acetaldehyde synthesized in the brain is necessary to induce ethanol (EtOH) reinforcement in naïve animals (acquisition phase). However, after chronic intake is achieved (maintenance phase), EtOH intake becomes independent of acetaldehyde generation or its levels. Glutamate has been reported to be associated with the maintenance of chronic EtOH intake. The levels of brain extracellular glutamate are modulated by 2 glial processes: glutamate reabsorption via an Na(+) -glutamate transporter (GLT1) and a cystine-glutamate exchanger. Chronic EtOH intake lowers GLT1 levels and increases extracellular glutamate. The administration of N-acetyl cysteine (NAC), a precursor of cystine, has been shown to reduce the relapse of several drugs of abuse, while NAC has not been tested on chronic EtOH intake or on EtOH's influence on the motivation for another drug. These were investigated in the present study. METHODS: (i) Rats bred for their high EtOH intake were allowed access to 10% EtOH and water up to 87 days. NAC was administered (30 and 60 mg/kg daily, intraperitoneally) for 14 consecutive days, either during the acquisition phase or the maintenance phase of EtOH drinking. (ii) In additional experiments, rats were allowed EtOH (10%) and water access for 61 days, after which EtOH was replaced by saccharin (0.3%) to determine both if chronic EtOH consumption influences saccharin intake and whether NAC modifies the post chronic EtOH saccharin intake. RESULTS: NAC did not influence the acquisition ("first hit") of chronic EtOH intake, but greatly inhibited (60 to 70%; p < 0.0001) EtOH intake when NAC was administered to animals that were consuming EtOH chronically. NAC did not influence saccharin intake in naïve animals. In animals that had consumed EtOH chronically and were thereafter offered a saccharin solution (0.3%), saccharin intake increased over 100% versus that of EtOH-untreated animals, an effect that was fully suppressed by NAC. CONCLUSIONS: N-acetyl cysteine, a drug approved for use in humans, markedly reduces chronic EtOH intake and abolishes the increased intake of saccharin stimulated by chronic EtOH drinking.

(R)-Salsolinol, a product of ethanol metabolism, stereospecifically induces behavioral sensitization and leads to excessive alcohol intake.

Ethanol is oxidized in the brain to acetaldehyde, which can condense with dopamine to generate (R/S)-salsolinol [(RS)-SAL]. Racemic salsolinol [(RS)-SAL] is self-infused by rats into the posterior ventral tegmental area (VTA) at significantly lower concentrations than those of acetaldehyde, suggesting that (RS)-SAL is a most active product of ethanol metabolism. Early studies showed that repeated intraperitoneal or intra-VTA administration of (RS)-SAL (10 mg/kg) induced conditioned place preference, led to locomotor sensitization and increased voluntary ethanol consumption. In the present study, we separated the (R)- and (S)-enantiomers from a commercial (RS)-SAL using a high-performance liquid chromatography with electrochemical detection system fitted with a ß-cyclodextrin-modified column. We injected (R)-SAL or (S)-SAL (30 pmol/1.0 µl) into the VTA of naïve UChB rats bred as alcohol drinkers to study whether one or both SAL enantiomers are responsible for the motivated behavioral effects, sensitization and increase in voluntary ethanol intake. The present results show that repeated administration of (R)-SAL leads to (1) conditioned place preference; (2) locomotor sensitization; and (3) marked increases in binge-like ethanol intake. Conversely, (S)-SAL did not influence any of these parameters. Overall, data indicate that (R)-SAL stereospecifically induces motivational effects, behavioral sensitization and increases ethanol intake.

The "first hit" toward alcohol reinforcement: role of ethanol metabolites.

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. Salsolinol administration leads to marked increases in voluntary EtOH intake, an effect inhibited by mu-opioid receptor blockers. In animals that have ingested EtOH chronically, the maintenance of alcohol intake is no longer influenced by EtOH metabolites, as intake is taken over by other brain systems. However, after EtOH withdrawal brain acetaldehyde has a major role in promoting binge-like drinking in the condition known as the "alcohol deprivation effect"; a condition seen in animals that have ingested alcohol chronically, are deprived of EtOH for extended periods, and are allowed EtOH re-access. The review also analyzes the behavioral effects of acetate, a metabolite that enters the brain and is responsible for motor incoordination at low doses of EtOH. Also discussed are the paradoxical effects of systemic acetaldehyde. Overall, evidence strongly suggests that brain-generated EtOH metabolites play a major role in the early ("first-hit") development of alcohol reinforcement and in the generation of relapse-like drinking.

Long-term inhibition of ethanol intake by the administration of an aldehyde dehydrogenase-2 (ALDH2)-coding lentiviral vector into the ventral tegmental area of rats.

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. In the chronic alcohol administration model, naïve animals administered the control vector and subsequently offered 10% ethanol and water ingested 8-9 g ethanol/kg body weight/day. The single administration of the ALDH2-coding vector prior to allowing ethanol availability reduced ethanol drinking by 85-90% (P < 0.001) for the 45 days tested. In the post-deprivation binge-drinking model, animals that had previously consumed ethanol chronically for 81 days were administered the lentiviral vector and were thereafter deprived of ethanol for three 7-day periods, each interrupted by a single 60-minute ethanol re-access after the last day of each deprivation period. Upon ethanol re-access, control vector-treated animals consumed intoxicating 'binge' amounts of ethanol, reaching intakes of 2.7 g ethanol/kg body weight in 60 minutes. The administration of the ALDH2-coding vector reduced re-access binge drinking by 75-80% (P < 0.001). This study shows that endowing the ventral tegmental with an increased ability to degrade acetaldehyde greatly reduces chronic alcohol consumption and post-deprivation binge drinking for prolonged periods and supports the hypothesis that brain-generated acetaldehyde promotes alcohol drinking.

Overexpression of hyperpolarization-activated cyclic nucleotide-gated channels into the ventral tegmental area increases the rewarding effects of ethanol in UChB drinking rats.

BACKGROUND: A number of studies have shown that ethanol (EtOH) activates dopamine neurocircuitries and is self-administered into the ventral tegmental area (VTA) of the rat brain. In vitro and in silico studies have showed that hyperpolarization-activated cyclic nucleotide-gated (HCN) ionic channels on VTA dopamine neurons may constitute a molecular target of EtOH; however, there is no in vivo evidence supporting this assumption. METHODS: Wistar-derived University of Chile Drinking (UChB) rats were microinjected into the VTA with a lentiviral vector coding for rat HCN-2 ionic channel or a control vector. Four days after vector administration, daily voluntary EtOH intake was assessed for 30 days under a free-access paradigm to 5% EtOH and water. After EtOH consumption studies, the effect of HCN-2 overexpression was also assessed on EtOH-induced conditioned place preference (CPP); EtOH-induced locomotion, and EtOH-induced dopamine release in the nucleus accumbens (NAcc). RESULTS: Rats microinjected with the HCN-2 coding vector into the VTA showed (i) a ~2-fold increase in their voluntary EtOH intake compared to control animals, (ii) lentiviral-HCN-2-treated animals also showed an increased CPP to EtOH (~3-fold), (iii) a significant higher locomotor activity (~2-fold), and (iv) increased dopamine release in NAcc upon systemic administration of EtOH (~2-fold). CONCLUSIONS: Overexpression of HCN-2 ionic channel in the VTA of rats results in an increase in voluntary EtOH intake, EtOH-induced CPP, locomotor activity, and dopamine release in NAcc, suggesting that HCN levels in the VTA are relevant for the rewarding properties of EtOH.

Gene specific modifications unravel ethanol and acetaldehyde actions.

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. Similarly aversive is an increased acetaldehyde level resulting from the inhibition of liver aldehyde dehydrogenase-2 (ALDH2) synthesis (by an antisense coding gene against aldh2 mRNA). The situation is diametrically different when acetaldehyde is generated in the brain. When the brain ventral tegmental area (VTA) is endowed with an increased ability to generate acetaldehyde (by transfection of liver rADH) the reinforcing effects of ethanol are increased, while a highly specific inhibition of catalase synthesis (by transduction of a shRNA anti catalase mRNA) virtually abolishes the reinforcing effects of ethanol as seen by a complete abolition of ethanol intake in rats bred for generations as high ethanol drinkers. Data shows two divergent effects of increases in acetaldehyde generation: aversive in the periphery but reinforcing in the brain.