| 1. |
- Schwandt, Melanie L., et al.
(författare)
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Gene-Environment Interactions and Response to Social Intrusion in Male and Female Rhesus Macaques
- 2010
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Ingår i: Biological Psychiatry. - : Elsevier BV. - 0006-3223 .- 1873-2402. ; 67:4, s. 323-330
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Tidskriftsartikel (refereegranskat)abstract
- Background: Genetic factors interact with environmental stressors to moderate risk for human psychopathology, but sex may also be an important mediating factor. Different strategies for coping with environmental stressors have evolved in males and females, and these differences may underlie the differential prevalence of certain types of psychopathology in the two sexes. In this study, we investigated the possibility of sex-specific gene-environment interactions in a nonhuman primate model of response to social threat. Methods: Rhesus macaques (77 males and 106 females) were exposed to an unfamiliar conspecific. Using factor analysis, we identified three behavioral factors characterizing the response to social threat. Monkeys were genotyped for the serotonin transporter-linked polymorphism (5-HTTLPR), and the effects of genotype, early life stress, and sex on behavioral responses were evaluated. Results: Factor analysis produced five factors: High-Risk Aggression, Impulsivity/Novelty-Seeking, Gregariousness/Boldness, Harm Avoidance, and Redirected Aggression. Overall, males displayed higher levels of High-Risk Aggression and Gregariousness/Boldness than females. Levels of High-Risk Aggression in males carrying the s allele were significantly higher if they were also exposed to early adversity in the form of peer rearing. Conclusions: Our findings support those from studies in humans suggesting that males are more vulnerable to externalizing or aggression-related disorders. The results highlight the importance of interactions that exist among behavior, genes, and the environment and suggest that sex differences in vulnerability to psychopathology may be grounded in our evolutionary history.
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| 2. |
- Pietrzak, Michal, 1987-, et al.
(författare)
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Ghrelin decreases sensitivity to negative feedback and increases prediction-error related caudate activity in humans, a randomized controlled trial
- 2024
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Ingår i: Neuropsychopharmacology. - : Springer Science+Business Media B.V.. - 0893-133X .- 1740-634X.
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Tidskriftsartikel (refereegranskat)abstract
- The stomach-derived hormone ghrelin plays not only a role in feeding, starvation, and survival, but it has been suggested to also be involved in the stress response, in neuropsychiatric conditions, and in alcohol and drug use disorders. Mechanisms related to reward processing might mediate ghrelin's broader effects on complex behaviors, as indicated by animal studies and mostly correlative human studies. Here, using a within-subject double-blind placebo-controlled design with intravenous ghrelin infusion in healthy volunteers (n = 30), we tested whether ghrelin alters sensitivity to reward and punishment in a reward learning task. Parameters were derived from a computational model of participants' task behavior. The reversal learning task with monetary rewards was performed during functional brain imaging to investigate ghrelin effects on brain signals related to reward prediction errors. Compared to placebo, ghrelin decreased punishment sensitivity (t = -2.448, p = 0.021), while reward sensitivity was unaltered (t = 0.8, p = 0.43). We furthermore found increased prediction-error related activity in the dorsal striatum during ghrelin administration (region of interest analysis: t-values >= 4.21, p-values <= 0.044). Our results support a role for ghrelin in reward processing that extends beyond food-related rewards. Reduced sensitivity to negative outcomes and increased processing of prediction errors may be beneficial for food foraging when hungry but could also relate to increased risk taking and impulsivity in the broader context of addictive behaviors.
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| 3. |
- Karlsson, Hanna, 1989-
(författare)
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From social drinking to alcohol addiction : Decision making and its neural substrates along a spectrum from social drinking to alcohol addiction
- 2024
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- For a minority of alcohol users, the initial sip of alcohol marks the start of a life-threatening process. This thesis studies cognitive mechanisms pertinent to alcohol addiction and its development, using a spectrum of individuals that range from healthy social drinkers, through people with hazardous use, to those suffering from alcohol addiction. Decision making can be altered in addiction, but less is known on the direct pharmacodynamic effects of alcohol intake in healthy people. Study 1 addressed decision making under the effects of moderate alcohol intoxication in healthy social drinkers using established behavioral economics tasks. The investigated processes encompassed both personal and social aspects of decision making. Within the personal domain, impulsivity and risk taking were investigated, while in the social domain, prosocial attitudes along with moral judgment were assessed. Moderate alcohol intoxication was found to impact only the social domain, leading to increased prosocial and utilitarian behaviors, but did not affect measures of impulsivity. Choosing alcohol over other natural rewards despite negative consequences is a central phenomenon of alcohol addiction. Two studies of this thesis investigated choice preference for alcohol compared to snack, using a cost manipulation paradigm, in light and heavy drinkers. Study 2 was a laboratory experiment whereas Study 3 was an imaging experiment for characterization of neural substrates. Cost was an important predictor of choice, as in both groups, alcohol choice was sensitive to cost in a parametric manner. This was mirrored in the brain by activity in value-based and salience regions, including orbitofrontal cortex and insula. In Study 2 we found that heavy drinkers showed generally higher alcohol choice preference and attenuated cost sensitivity. Failure to replicate this finding in Study 3, was possibly due to the artificial scanner environment. Craving is a key component in the cycle of addiction and a determinant of relapse, making it an important target for treatment interventions. Study 4 was a randomized sham-controlled trial using repetitive transcranial magnetic stimulation (rTMS) targeting the insula as a method to reduce craving and alcohol use in people suffering from alcohol addiction. An overall decrease in alcohol consumption and craving were seen, but did not differ between sham stimulation and rTMS targeting the insula. In summary, this thesis provides some insights into cognitive mechanisms related to alcohol addiction and processes that may be implicated in its development. During a moderate acute alcohol intoxication in healthy social drinkers, social decision-making is influenced, leading to increased utilitarian and altruistic behaviors. Thus, deficits in prosocial behaviors in people with alcohol addiction are unlikely to result from direct pharmacodynamic effects of alcohol, but are rather likely to reflect a selection of vulnerable individuals, consequences of the addictive process, or both. In individuals at risk of developing alcohol addiction, the sensitivity to the costs associated with choosing alcohol over an alternative reward is largely preserved, though it might be reduced compared to light, non-problem drinkers. Modulation of the insula cortex with TMS was not successful in decreasing alcohol use in individuals with alcohol addiction.
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| 4. |
- Domi, Esi, et al.
(författare)
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Neurobiology of alcohol seeking behavior
- 2021
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Ingår i: Journal of Neurochemistry. - : Wiley. - 0022-3042 .- 1471-4159. ; 157:5, s. 1585-1614
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Forskningsöversikt (refereegranskat)abstract
- Alcohol addiction is a chronic relapsing brain disease characterized by an impaired ability to stop or control alcohol use despite adverse consequences. A main challenge of addiction treatment is to prevent relapse, which occurs in more than >50% of newly abstinent patients with alcohol disorder within 3 months. In people suffering from alcohol addiction, stressful events, drug-associated cues and contexts, or re-exposure to a small amount of alcohol trigger a chain of behaviors that frequently culminates in relapse. In this review, we first present the preclinical models that were developed for the study of alcohol seeking behavior, namely the reinstatement model of alcohol relapse and compulsive alcohol seeking under a chained schedule of reinforcement. We then provide an overview of the neurobiological findings obtained using these animal models, focusing on the role of opioids systems, corticotropin-release hormone and neurokinins, followed by dopaminergic, glutamatergic, and GABAergic neurotransmissions in alcohol seeking behavior.
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| 5. |
- Aoun, E. G., et al.
(författare)
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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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Ingår i: Molecular Psychiatry. - : NATURE PUBLISHING GROUP. - 1359-4184 .- 1476-5578. ; 23:6, s. 1466-1473
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Tidskriftsartikel (refereegranskat)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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| 6. |
- Augier, Eric, et al.
(författare)
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The GABA(B) Positive Allosteric Modulator ADX71441 Attenuates Alcohol Self-Administration and Relapse to Alcohol Seeking in Rats
- 2017
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Ingår i: Neuropsychopharmacology. - : NATURE PUBLISHING GROUP. - 0893-133X .- 1740-634X. ; 42:9, s. 1789-1799
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Tidskriftsartikel (refereegranskat)abstract
- GABAergic signaling is involved in modulating the reinforcing properties of alcohol, and GABA(B) receptors have been proposed as a potential target for clinical treatment of alcoholism. The orthosteric GABA(B) receptor agonist baclofen has been shown to suppress operant self-administration of alcohol in animals and alcohol use in alcohol-dependent patients, but its utility is limited by a narrow therapeutic index. We tested the effects of ADX71441, a novel GABA(B) receptor positive allosteric modulator, on alcohol-related behaviors in rats. We first assessed the effects of ADX71441 ( 1, 3, 10 and 30 mg/kg, I.P.) on both non-dependent and dependent male Wistar rats trained to self-administer 20% alcohol. We then determined the effects of ADX71441 on stress-induced as well as cue-induced relapse-like behavior. Finally, we sought to identify the brain regions through which ADX71441 may act to prevent relapse-like behavior by mapping the neuronal activation induced by stress-induced reinstatement of alcohol-seeking using c-Fos immunohistochemistry. ADX71441 dose-dependently decreased alcohol self-administration of both dependent and non-dependent animals, but its potency was higher in alcohol-dependent rats. Furthermore, both cue-and stress-induced alcohol seeking were blocked by the GABA(B) receptor positive allosteric modulator. Finally, pretreatment with 3 mg/kg of ADX71441 before stress-induced reinstatement significantly decreased c-Fos expression in a network of brain regions implicated in stress-induced relapse, comprising the nucleus accumbens shell, the dorsal raphe nucleus and the medial prefrontal cortex. Our findings support a causal role of GABAB receptors in alcohol reinforcement and relapse to alcohol seeking. These effects are observed in the absence of significant sedative side effects. Jointly, these observations indicate that GABAB receptor positive allosteric modulators merit being tested clinically for the treatment of alcoholism. Our data also point to a potential biomarker of target engagement for early clinical studies.
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| 7. |
- Barbier, Estelle, et al.
(författare)
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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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Ingår i: Molecular Psychiatry. - : NATURE PUBLISHING GROUP. - 1359-4184 .- 1476-5578. ; 22:12, s. 1746-1758
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Tidskriftsartikel (refereegranskat)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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| 8. |
- Barbier, Estelle, et al.
(författare)
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Downregulation of Synaptotagmin 1 in the Prelimbic Cortex Drives Alcohol-Associated Behaviors in Rats
- 2021
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Ingår i: Biological Psychiatry. - : Elsevier BV. - 0006-3223 .- 1873-2402. ; 89:4, s. 398-406
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Tidskriftsartikel (refereegranskat)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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| 9. |
- Barbier, Estelle, et al.
(författare)
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mTORC and ProSAPiP1: How Alcohol Changes Synapses of Reward Circuitry
- 2017
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Ingår i: Neuron. - : CELL PRESS. - 0896-6273 .- 1097-4199. ; 96:1
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)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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| 10. |
- Barchiesi, Riccardo, 1989-, et al.
(författare)
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An epigenetic mechanism for over-consolidation of fear memories
- 2022
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Ingår i: Molecular Psychiatry. - : Springer Nature. - 1359-4184 .- 1476-5578. ; 27:12, s. 4893-4904
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Tidskriftsartikel (refereegranskat)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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