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- Bendre, Megha, et al.
(author)
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Early life stress and voluntary alcohol consumption in relation to Maoa methylation in male rats.
- 2019
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In: Alcohol. - : Elsevier BV. - 0741-8329 .- 1873-6823. ; 79, s. 7-16
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Journal article (peer-reviewed)abstract
- Early life stress (ELS) or alcohol consumption can influence DNA methylation and affect gene expression. The monoamine oxidase A (Maoa) encodes the enzyme that metabolizes monoaminergic neurotransmitters crucial for the stress response, alcohol reward, and reinforcement. Previously, we reported lower Maoa expression in the nucleus accumbens and dorsal striatum of male rats exposed to ELS during the first three postnatal weeks, and to voluntary alcohol consumption in adulthood, compared with controls. The present study continued to investigate the effect of ELS and alcohol consumption on Maoa methylation, and its relation to Maoa expression in these animals. We selected candidate CpGs after performing next-generation bisulfite sequencing of the Maoa promoter, intron 1-5, exons 5 and 6, together comprised of 107 CpGs, in a subgroup of rats. Pyrosequencing was used to analyse the methylation of ten candidate CpGs in the promoter and intron 1 in the entire sample. ELS and alcohol displayed an interaction effect on CpG-specific methylation in the dorsal striatum. CpG-specific methylation correlated with Maoa expression, corticosterone levels, and alcohol consumption in a brain region-specific manner. CpG-specific methylation in the Maoa promoter was a potential moderator of the interaction of ELS with alcohol consumption on Maoa expression in the NAc. However, the findings were sparse, did not survive correction for multiple testing, and the magnitude of differences in methylation levels was small. In conclusion, CpG-specific Maoa methylation in the promoter and intron 1 may associate with ELS, alcohol consumption and Maoa expression in reward-related brain regions.
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| 3. |
- Bendre, Megha, et al.
(author)
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Effect of voluntary alcohol consumption on Maoa expression in the mesocorticolimbic brain of adult male rats previously exposed to prolonged maternal separation. : Maoa,ELS and alcohol
- 2015
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In: Translational Psychiatry. - : Springer Science and Business Media LLC. - 2158-3188. ; 5
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Journal article (peer-reviewed)abstract
- Discordant associations between monoamine oxidase A (MAOA) genotype and high alcohol drinking have been reported in human and non-human primates. Environmental influences likely moderate genetic susceptibility. The biological basis for this interplay remains elusive, and inconsistencies call for translational studies in which conditions can be controlled and brain tissue is accessible. The present study investigated whether early life stress and subsequent adult episodic alcohol consumption affect Maoa expression in stress- and reward-related brain regions in the rat. Outbred Wistar rats were exposed to rearing conditions associated with stress (prolonged maternal separation) or no stress during early life, and given free choice between alcohol and/or water in adulthood. Transcript levels of Maoa were assessed in the ventral tegmental area, nucleus accumbens (NAc), medial prefrontal cortex, cingulate cortex, amygdala and dorsal striatum (DS). Blood was collected to assess corticosterone levels. After alcohol consumption, lower blood corticosterone and Maoa expression in the NAc and DS were found in rats exposed to early life stress compared with control rats. An interaction between early life stress and voluntary alcohol intake was found in the NAc. Alcohol intake before death correlated negatively with Maoa expression in DS in high alcohol-drinking rats exposed to early life stress. Maoa expression is sensitive to adulthood voluntary alcohol consumption in the presence of early life stress in outbred rats. These findings add knowledge of the molecular basis of the previously reported associations between early life stress, MAOA and susceptibility to alcohol misuse.
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| 5. |
- Bendre, Megha
(author)
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Predictors of Alcohol Misuse : Role of MAOA Genotype, Methylation, Transcription, and Negative and Positive Environmental factors
- 2019
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Doctoral thesis (other academic/artistic)abstract
- Alcohol misuse is a risk factor for alcohol use disorder (AUD). Gene-environment interactions contribute to the risk or resilience for AUD. A functional polymorphism in the promoter of the monoamine oxidase A gene (MAOA-uVNTR), in interaction with negative environment (Eneg), is associated with alcohol misuse and AUD. Men carrying short (MAOA-S), and women carrying long (MAOA-L), MAOA-uVNTR alleles who experienced maltreatment or poor parent-child relationships are at increased susceptibility to alcohol misuse and AUD. This thesis assessed whether the association of MAOAxEneg with the risk of AUD is moderated by MAOA methylation or positive environment and whether MAOA methylation-associated changes in MAOA expression in the stress- and reward-related brain regions is an underlying mechanism.The thesis reveals that the association of MAOAxEneg with alcohol misuse is moderated by MAOA methylation in men, but not in women. In the clinical sample, men carrying MAOA-S allele who experienced maltreatment and had low MAOA methylation displayed higher alcohol-related problems than those without maltreatment or MAOA-L carriers with and without maltreatment. Furthermore, the quality of the parent–child relationship moderated the association of MAOAxEneg with alcohol misuse in a sex- and AUD stage-dependent manner. In the non-clinical sample of adolescents, girls carrying MAOA-L allele who experienced maltreatment and poor parent–child relationship displayed higher alcohol consumption, whereas those with average or good parent–child relationship had lower alcohol consumption. In the clinical sample of adolescents, however, no such association was observed. These results suggest that a good parent–child relationship protects MAOA susceptibility genotype carriers exposed to maltreatment during the early stages of alcohol use. The preclinical studies revealed that the male rats exposed to Eneg and alcohol had higher CpG-specific Maoa promoter methylation, which was associated with lower Maoa expression in the nucleus accumbens than the control rats. Thus, MAOA methylation-associated changes in MAOA expression in the nucleus accumbens might mediate the effect of environment on alcohol use.The thesis contributes to the understanding of biological mechanisms underlying MAOAxEnvironment effect and the critical role of MAOA methylation and positive environment in moderating risk and resilience for AUD. Also, the identification of subgroups may benefit from personalised interventions for AUD.
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| 7. |
- Comasco, Erika, et al.
(author)
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Alpha 2a-Adrenoceptor Gene Expression and Early Life Stress-Mediated Propensity to Alcohol Drinking in Outbred Rats
- 2015
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In: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1661-7827 .- 1660-4601. ; 12:7, s. 7154-7171
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Journal article (peer-reviewed)abstract
- Stressful events early in life, later high alcohol consumption and vulnerability to alcohol use disorder (AUD) are tightly linked. Norepinephrine is highly involved in the stress response and the alpha 2A-adrenoceptor, which is an important regulator of norepinephrine signalling, is a putative target in pharmacotherapy of AUD. The aim of the present study was to investigate the effects of early-life stress and adult voluntary alcohol drinking on the alpha 2A-adrenoceptor. The relative expression and promoter DNA methylation of the Adra2a gene were measured in the hypothalamus, a key brain region in stress regulation. A well-characterized animal model of early-life stress was used in combination with an episodic voluntary drinking in adulthood. Alcohol drinking rats with a history of early-life stress had lower Adra2a expression than drinking rats not exposed to stress. Alcohol intake and Adra2a gene expression were negatively correlated in high-drinking animals, which were predominantly rats subjected to early-life stress. The results provide support for a link between early-life stress, susceptibility for high alcohol consumption, and low Adra2a expression in the hypothalamus. These findings can increase our understanding of the neurobiological basis for vulnerability to initiate risk alcohol consumption and individual differences in the response to 2A-adrenoceptor agonists.
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| 8. |
- Comasco, Erika, 1982-, et al.
(author)
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Constitutive serotonin transporter reduction resembles maternal separation with regard to stress-related gene expression
- 2019
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In: ACS Chemical Neuroscience. - : American Chemical Society (ACS). - 1948-7193. ; 10:7, s. 3132-3142
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Journal article (peer-reviewed)abstract
- Interactive effects between allelic variants of the serotonin transporter (5-HTT) promoter-linked polymorphic region (5-HTTLPR) and stressors on depression symptoms have been documented, as well as questioned, by meta-analyses. Translational models of constitutive 5-htt reduction and experimentally controlled stressors often led to inconsistent behavioral and molecular findings and often did not include females. The present study sought to investigate the effect of 5-htt genotype, maternal separation, and sex on the expression of stress-related candidate genes in the rat hippocampus and frontal cortex. The mRNA expression levels of Avp, Pomc, Crh, Crhbp, Crhr1, Bdnf, Ntrk2, Maoa, Maob, and Comt were assessed in the hippocampus and frontal cortex of 5-htt± and 5-htt+/+ male and female adult rats exposed, or not, to daily maternal separation for 180 min during the first 2 postnatal weeks. Gene- and brain region-dependent, but sex-independent, interactions between 5-htt genotype and maternal separation were found. Gene expression levels were higher in 5-htt+/+ rats not exposed to maternal separation compared with the other experimental groups. Maternal separation and 5-htt+/− genotype did not yield additive effects on gene expression. Correlative relationships, mainly positive, were observed within, but not across, brain regions in all groups except in non-maternally separated 5-htt+/+ rats. Gene expression patterns in the hippocampus and frontal cortex of rats exposed to maternal separation resembled the ones observed in rats with reduced 5-htt expression regardless of sex. These results suggest that floor effects of 5-htt reduction and maternal separation might explain inconsistent findings in humans and rodents.
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| 10. |
- Engel, Jörgen, 1942, et al.
(author)
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A ghrelin receptor (GHS-R1A) antagonist attenuates the rewarding properties of morphine and increases opioid peptide levels in reward areas in mice
- 2015
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In: European Neuropsychopharmacology. - : Elsevier BV. - 0924-977X .- 1873-7862. ; 25:12, s. 2364-2371
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Journal article (peer-reviewed)abstract
- Gut-brain hormones such as ghrelin have recently been suggested to have a role in reward regulation. Ghrelin was traditionally known to regulate food intake and body weight homoeostasis. In addition, recent work has pin-pointed that this peptide has a novel role in drug-induced reward, including morphine-induced increase in the extracellular levels of accumbal dopamine in rats. Herein the effect of the ghrelin receptor (GHS-R1A) antagonist, JMV2959, on morphine-induced activation of the mesolimbic dopamine system was investigated in mice. In addition, the effects of JMV2959 administration on opioid peptide levels in reward related areas were investigated. In the present series of experiment we showed that peripheral JMV2959 administration, at a dose with no effect per se, attenuates the ability of morphine to cause locomotor stimulation, increase the extracellular levels of accumbal dopamine and to condition a place preference in mice. JMV2959 administration significantly increased tissue levels of Metenkephalin-Arg(6)Phe(7) in the ventral tegmental area, dynorphin B in hippocampus and Leuenkephalin-Arg(6) in striatum. We therefore hypothesise that JMV2959 prevents morphine-induced reward via stimulation of delta receptor active peptides in striatum and ventral tegmental areas. In addition, hippocampal peptides that activate kappa receptor may be involved in JMV2959's ability to regulate memory formation of reward. Given that development of drug addiction depends, at least in part, of the effects of addictive drugs on the mesolimbic dopamine system the present data suggest that GIS-R1A antagonists deserve to be elucidated as novel treatment strategies of opioid addiction.
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