| 1. |
- Aoun, E. G., et al.
(author)
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A relationship between the aldosterone-mineralocorticoid receptor pathway and alcohol drinking: preliminary translational findings across rats, monkeys and humans
- 2018
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In: Molecular Psychiatry. - : NATURE PUBLISHING GROUP. - 1359-4184 .- 1476-5578. ; 23:6, s. 1466-1473
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Journal article (peer-reviewed)abstract
- Aldosterone regulates electrolyte and fluid homeostasis through binding to the mineralocorticoid receptors (MRs). Previous work provides evidence for a role of aldosterone in alcohol use disorders (AUDs). We tested the hypothesis that high functional activity of the mineralocorticoid endocrine pathway contributes to vulnerability for AUDs. In Study 1, we investigated the relationship between plasma aldosterone levels, ethanol self-administration and the expression of CYP11B2 and MR (NR3C2) genes in the prefrontal cortex area (PFC) and central nucleus of the amygdala (CeA) in monkeys. Aldosterone significantly increased after 6- and 12-month ethanol self-administration. NR3C2 expression in the CeA was negatively correlated to average ethanol intake during the 12 months. In Study 2, we measured Nr3c2 mRNA levels in the PFC and CeA of dependent and nondependent rats and the correlates with ethanol drinking during acute withdrawal. Low Nr3c2 expression levels in the CeA were significantly associated with increased anxiety-like behavior and compulsive-like drinking in dependent rats. In Study 3, the relationship between plasma aldosterone levels, alcohol drinking and craving was investigated in alcohol-dependent patients. Non-abstinent patients had significantly higher aldosterone levels than abstinent patients. Aldosterone levels positively correlated with the number of drinks consumed, craving and anxiety scores. These findings support a relationship between ethanol drinking and the aldosterone/MR pathway in three different species.
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| 2. |
- Barbier, Estelle, et al.
(author)
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A molecular mechanism for choosing alcohol over an alternative reward
- 2018
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 360:6395
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Journal article (peer-reviewed)abstract
- Alcohol addiction leads to increased choice of alcohol over healthy rewards. We established an exclusive choice procedure in which similar to 15% of outbred rats chose alcohol over a high-value reward. These animals displayed addiction-like traits, including high motivation to obtain alcohol and pursuit of this drug despite adverse consequences. Expression of the g-aminobutyric acid (GABA) transporter GAT-3 was selectively decreased within the amygdala of alcohol-choosing rats, whereas a knockdown of this transcript reversed choice preference of rats that originally chose a sweet solution over alcohol. GAT-3 expression was selectively decreased in the central amygdala of alcohol-dependent people compared to those who died of unrelated causes. Impaired GABA clearance within the amygdala contributes to alcohol addiction, appears to translate between species, and may offer targets for new pharmacotherapies for treating this disorder.
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| 3. |
- Barbier, Estelle, et al.
(author)
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Dependence-induced increase of alcohol self-administration and compulsive drinking mediated by the histone methyltransferase PRDM2
- 2017
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In: Molecular Psychiatry. - : NATURE PUBLISHING GROUP. - 1359-4184 .- 1476-5578. ; 22:12, s. 1746-1758
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Journal article (peer-reviewed)abstract
- Epigenetic processes have been implicated in the pathophysiology of alcohol dependence, but the specific molecular mechanisms mediating dependence-induced neuroadaptations remain largely unknown. Here, we found that a history of alcohol dependence persistently decreased the expression of Prdm2, a histone methyltransferase that monomethylates histone 3 at the lysine 9 residue (H3K9me1), in the rat dorsomedial prefrontal cortex (dmPFC). Downregulation of Prdm2 was associated with decreased H3K9me1, supporting that changes in Prdm2 mRNA levels affected its activity. Chromatin immunoprecipitation followed by massively parallel DNA sequencing showed that genes involved in synaptic communication are epigenetically regulated by H3K9me1 in dependent rats. In non-dependent rats, viral-vector-mediated knockdown of Prdm2 in the dmPFC resulted in expression changes similar to those observed following a history of alcohol dependence. Prdm2 knockdown resulted in increased alcohol self-administration, increased aversion-resistant alcohol intake and enhanced stress-induced relapse to alcohol seeking, a phenocopy of postdependent rats. Collectively, these results identify a novel epigenetic mechanism that contributes to the development of alcohol-seeking behavior following a history of dependence.
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| 4. |
- Barbier, Estelle, et al.
(author)
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DNA Methylation in the Medial Prefrontal Cortex Regulates Alcohol-Induced Behavior and Plasticity
- 2015
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In: Journal of Neuroscience. - : Society for Neuroscience. - 0270-6474 .- 1529-2401. ; 35:15, s. 6153-6164
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Journal article (peer-reviewed)abstract
- Recent studies have suggested an association between alcoholism and DNA methylation, a mechanism that can mediate long-lasting changes in gene transcription. Here, we examined the contribution of DNA methylation to the long-term behavioral and molecular changes induced by a history of alcohol dependence. In search of mechanisms underlying persistent rather than acute dependence-induced neuroadaptations, we studied the role of DNA methylation regulating medial prefrontal cortex (mPFC) gene expression and alcohol-related behaviors in rats 3 weeks into abstinence following alcohol dependence. Postdependent rats showed escalated alcohol intake, which was associated with increased DNA methylation as well as decreased expression of genes encoding synaptic proteins involved in neurotransmitter release in the mPFC. Infusion of the DNA methyltransferase inhibitor RG108 prevented both escalation of alcohol consumption and dependence-induced downregulation of 4 of the 7 transcripts modified in postdependent rats. Specifically, RG108 treatment directly reversed both downregulation of synaptotagmin 2 (Syt2) gene expression and hypermethylation on CpG#5 of its first exon. Lentiviral inhibition of Syt2 expression in the mPFC increased aversion-resistant alcohol drinking, supporting a mechanistic role of Syt2 in compulsive-like behavior. Our findings identified a functional role of DNA methylation in alcohol dependence-like behavioral phenotypes and a candidate gene network that may mediate its effects. Together, these data provide novel evidence for DNA methyltransferases as potential therapeutic targets in alcoholism.
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| 5. |
- Barbier, Estelle, et al.
(author)
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Downregulation of Synaptotagmin 1 in the Prelimbic Cortex Drives Alcohol-Associated Behaviors in Rats
- 2021
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In: Biological Psychiatry. - : Elsevier BV. - 0006-3223 .- 1873-2402. ; 89:4, s. 398-406
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Journal article (peer-reviewed)abstract
- Background: Alcohol addiction is characterized by persistent neuroadaptations in brain structures involved in motivation, emotion, and decision making, including the medial prefrontal cortex, the nucleus accumbens, and the amygdala. We previously reported that induction of alcohol dependence was associated with long-term changes in the expression of genes involved in neurotransmitter release. Specifically, Syt1, which plays a key role in neurotransmitter release and neuronal functions, was downregulated. Here, we therefore examined the role of Syt1 in alcohol-associated behaviors in rats. Methods: We evaluated the effect of Syt1 downregulation using an adeno-associated virus (AAV) containing a short hairpin RNA against Syt1. Cre-dependent Syt1 was also used in combination with an rAAV2 retro-Cre virus to assess circuit-specific effects of Syt1 knockdown (KD). Results: Alcohol-induced downregulation of Syt1 is specific to the prelimbic cortex (PL), and KD of Syt1 in the PL resulted in escalated alcohol consumption, increased motivation to consume alcohol, and increased alcohol drinking despite negative consequences (“compulsivity”). Syt1 KD in the PL altered the excitation/inhibition balance in the basolateral amygdala, while the nucleus accumbens core was unaffected. Accordingly, a projection-specific Syt1 KD in the PL–basolateral amygdala projection was sufficient to increase compulsive alcohol drinking, while a KD of Syt1 restricted to PL–nucleus accumbens core projecting neurons had no effect on tested alcohol-related behaviors. Conclusions: Together, these data suggest that dysregulation of Syt1 is an important mechanism in long-term neuroadaptations observed after a history of alcohol dependence, and that Syt1 regulates alcohol-related behaviors in part by affecting a PL–basolateral amygdala brain circuit. © 2020 Society of Biological Psychiatry
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| 6. |
- Barbier, Estelle, et al.
(author)
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mTORC and ProSAPiP1: How Alcohol Changes Synapses of Reward Circuitry
- 2017
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In: Neuron. - : CELL PRESS. - 0896-6273 .- 1097-4199. ; 96:1
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Journal article (other academic/artistic)abstract
- Alcohol addiction is characterized by broad and persistent changes in brain function, but the underlying neural adaptations remain largely unknown. In this issue of Neuron, Laguesse et al. (2017) describe a neural mechanism through which long-term alcohol exposure induces structural and synaptic adaptations that promote excessive alcohol use.
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| 7. |
- Barchiesi, Riccardo, 1989-, et al.
(author)
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An epigenetic mechanism for over-consolidation of fear memories
- 2022
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In: Molecular Psychiatry. - : Springer Nature. - 1359-4184 .- 1476-5578. ; 27:12, s. 4893-4904
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Journal article (peer-reviewed)abstract
- Excessive fear is a hallmark of anxiety disorders, a major cause of disease burden worldwide. Substantial evidence supports a role of prefrontal cortex-amygdala circuits in the regulation of fear and anxiety, but the molecular mechanisms that regulate their activity remain poorly understood. Here, we show that downregulation of the histone methyltransferase PRDM2 in the dorsomedial prefrontal cortex enhances fear expression by modulating fear memory consolidation. We further show that Prdm2 knock-down (KD) in neurons that project from the dorsomedial prefrontal cortex to the basolateral amygdala (dmPFC-BLA) promotes increased fear expression. Prdm2 KD in the dmPFC-BLA circuit also resulted in increased expression of genes involved in synaptogenesis, suggesting that Prdm2 KD modulates consolidation of conditioned fear by modifying synaptic strength at dmPFC-BLA projection targets. Consistent with an enhanced synaptic efficacy, we found that dmPFC Prdm2 KD increased glutamatergic release probability in the BLA and increased the activity of BLA neurons in response to fear-associated cues. Together, our findings provide a new molecular mechanism for excessive fear responses, wherein PRDM2 modulates the dmPFC -BLA circuit through specific transcriptomic changes.
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| 8. |
- Barchiesi, Riccardo, 1989-
(author)
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Overlapping Neural Substrates of Alcohol- and Anxiety-Related Behavior in the Rat
- 2021
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Doctoral thesis (other academic/artistic)abstract
- Alcohol use is a leading cause of death and disease worldwide. A large part of this disease burden is associated with alcohol use disorder (AUD), a diagnostic category characterized by excessive use in spite of negative consequences ("compulsive use"), a loss of control over intake, and choice of alcohol over natural rewards. These behavioral symptoms are believed to reflect the emergence of persistent neuroadaptations in key brain regions that exert control over motivated behavior. A major challenge to addressing the treatment needs of patients with AUD is the high prevalence of co-occurring psychiatric disorders, of which anxiety disorders are the most common. Both AUD and anxiety disorders are characterized by broad changes in gene expression within brain regions that include the prelimbic cortex (PL) and the amygdala complex. Although the risk for AUD has a substantial genetic component, heavy alcohol use and stress also contribute to disease risk. Our lab previously identified DNA hypermethylation as a mechanism behind alcohol-induced downregulation of prelimbic Syt1 and Prdm2. In a subsequent study, our lab demonstrated a functional role of Prdm2 in alcohol-associated behaviors. In the work that constitutes this thesis, we have further investigated the behavioral consequences of Syt1 and Prdm2 downregulation. We found that Syt1 knock-down in the PL of non-dependent rats is sufficient to promote several behaviors that model critical aspects of AUD. We further identified the PL-basolateral amygdala (BLA) projection as a key brain circuit within which Syt1 knock-down promotes compulsive-like alcohol intake. In another study, we showed that Prdm2 knock-down in the PL increases the expression of fear memory, a central feature of anxiety disorders. Knock-down after memory formation (consolidation) did not increase the fear expression, indicating that Prdm2 regulates fear memory consolidation. We further showed that knock-down of Prdm2 in the PL-BLA projection was sufficient to promote the increased fear expression. Transcriptome analysis specifically in neurons projecting from the PL to the BLA showed a marked up-regulation of genes involved in synaptogenesis, suggesting that Prdm2 downregulation leads to excessive fear by strengthening fear memory consolidation in the PL-BLA circuit. In a third study, we used a model of social defeat- and witness stress to investigate mechanisms of co-occurring escalated alcohol intake and increased anxiety-like behavior ("comorbidity"). We recapitulated the broad range of individual stress responses observed in human populations. With gene expression analysis, we identified a marked upregulation of Avp in the amygdala of rats with "co-morbid" characteristics, and this upregulation correlated with the magnitude of the comorbidity. Together, our findings highlight the contribution of epigenetic mechanisms in regulating the behavioral consequences of alcohol-dependence, and identify specific downstream target genes whose expression is influenced by alcohol-induced epigenetic reprogramming to mediate long-term behavioral consequences. Our work also identifies amygdala Avp as a possible neurobiological substrate of individual susceptibility for stress-induced alcohol- and anxiety-related behaviors.
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| 9. |
- Barchiesi, Riccardo, et al.
(author)
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Stress-induced escalation of alcohol self-administration, anxiety-like behavior, and elevated amygdala Avp expression in a susceptible subpopulation of rats
- 2021
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In: Addiction Biology. - : Wiley. - 1355-6215 .- 1369-1600. ; 26:5
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Journal article (peer-reviewed)abstract
- Comorbidity between alcohol use and anxiety disorders is associated with more severe symptoms and poorer treatment outcomes than either of the conditions alone. There is a well-known link between stress and the development of these disorders, with post-traumatic stress disorder as a prototypic example. Post-traumatic stress disorder can arise as a consequence of experiencing traumatic events firsthand and also after witnessing them. Here, we used a model of social defeat and witness stress in rats, to study shared mechanisms of stress-induced anxiety-like behavior and escalated alcohol self-administration. Similar to what is observed clinically, we found considerable individual differences in susceptibility and resilience to the stress. Both among defeated and witness rats, we found a subpopulation in which exposure was followed by emergence of increased anxiety-like behavior and escalation of alcohol self-administration. We then profiled gene expression in tissue from the amygdala, a key brain region in the regulation of stress, alcohol use, and anxiety disorders. When comparing "comorbid" and resilient socially defeated rats, we identified a strong upregulation of vasopressin and oxytocin, and this correlated positively with the magnitude of the alcohol self-administration and anxiety-like behavior. A similar trend was observed in comorbid witness rats. Together, our findings provide novel insights into molecular mechanisms underpinning the comorbidity of escalated alcohol self-administration and anxiety-like behavior.
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| 10. |
- Domi, Ana, 1990, et al.
(author)
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Targeting the Opioid Receptors: A Promising Therapeutic Avenue for Treatment in "Heavy Drinking Smokers"
- 2021
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In: Alcohol and Alcoholism. - : Oxford University Press (OUP). - 0735-0414 .- 1464-3502. ; 56:2, s. 127-138
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Journal article (peer-reviewed)abstract
- Aims: Despite a general decline in tobacco use in the last decades, the prevalence of tobacco smoking in individuals with alcohol use disorder (AUD) remains substantial (45-50%). Importantly, the co-use of both substances potentiates the adverse effects, making it a significant public health problem. Substantial evidence suggests that AUD and Tobacco use disorder (TUD) may share common mechanisms. Targeting these mechanisms may therefore provide more effective therapy. Numerous studies describe a potential role of the endogenous opioid system in both AUD and TUD. Reviewing this literature, we aim to evaluate the efficacy of molecules that target the opioid system as promising therapeutic interventions for treating alcohol and tobacco co-use disorders. Methods: We provide a synthesis of the current epidemiological knowledge of alcohol and tobacco co-use disorders. We evaluate clinical and preclinical research that focuses on the regulation of the endogenous opioid system in alcohol, nicotine, and their interactions. Results: The epidemiological data confirm that smoking stimulates heavy drinking and facilitates alcohol craving. Pharmacological findings suggest that treatments that are efficacious in the dual addiction provide a beneficial treatment outcome in comorbid AUD and TUD. In this regard, MOP, DOP and NOP-receptor antagonists show promising results, while the findings prompt caution when considering KOP-receptor antagonists as a treatment option in alcohol and tobacco co-use disorders. Conclusions: Existing literature suggests a role of the opioid system in sustaining the high comorbidity rates of AUD and TUD. Molecules targeting opioid receptors may therefore represent promising therapeutic interventions in 'heavy drinking smokers.'
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