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| 2. |
- Bendre, Megha, et al.
(författare)
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Early life stress and voluntary alcohol consumption in relation to Maoa methylation in male rats.
- 2019
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Ingår i: Alcohol. - : Elsevier BV. - 0741-8329 .- 1873-6823. ; 79, s. 7-16
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Comasco, Erika, et al.
(författare)
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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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Ingår i: International Journal of Environmental Research and Public Health. - : MDPI AG. - 1661-7827 .- 1660-4601. ; 12:7, s. 7154-7171
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Tidskriftsartikel (refereegranskat)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. |
- Granholm, Linnea, et al.
(författare)
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Episodic Ethanol Exposure in Adolescent Rats Causes Residual Alterations in Endogenous Opioid Peptides
- 2018
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Ingår i: Frontiers in Psychiatry. - : FRONTIERS MEDIA SA. - 1664-0640. ; 9
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Tidskriftsartikel (refereegranskat)abstract
- Adolescent binge drinking is associated with an increased risk of substance use disorder, but how ethanol affects the central levels of endogenous opioid peptides is still not thoroughly investigated. The aim of this study was to examine the effect of repeated episodic ethanol exposure during adolescence on the tissue levels of three different endogenous opioid peptides in rats. OutbredWistar rats received orogastric (i.e., gavage) ethanol for three consecutive days per week between 4 and 9 weeks of age. At 2 h and 3 weeks, respectively, after the last exposure, beta-endorphin, dynorphin B and Met-enkephalin-Arg(6)Phe(7) (MEAP) were analyzed with radioimmunoassay. Beta-endorphin levels were low in the nucleus accumbens during ethanol intoxication. Remaining effects of adolescent ethanol exposure were found especially for MEAP, with low levels in the amygdala, and high in the substantia nigra and ventral tegmental area three weeks after the last exposure. In the hypothalamus and pituitary, the effects of ethanol on beta-endorphin were dependent on time from the last exposure. An interaction effect was also found in the accumbal levels of MEAP and nigral dynorphin B. These results demonstrate that repeated episodic exposure to ethanol during adolescence affected opioid peptide levels in regions involved in reward and reinforcement as well as stress response. These alterations in opioid networks after adolescent ethanol exposure could explain, in part, the increased risk for high ethanol consumption later in life.
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| 9. |
- Granholm, Linnea, et al.
(författare)
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Impact of adolescent ethanol exposure and adult amphetamine self-administration on evoked striatal dopamine release in male rats
- 2015
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Ingår i: Psychopharmacology. - : Springer Science and Business Media LLC. - 0033-3158 .- 1432-2072. ; 232:24, s. 4421-4431
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Tidskriftsartikel (refereegranskat)abstract
- Adolescent binge drinking is common and associated with increased risk of substance use disorders. Transition from recreational to habitual ethanol consumption involves alterations in dorsal striatal function, but the long-term impact of adolescent ethanol exposure upon this region remains unclear. This study aimed to characterise and describe relationships between adolescent ethanol exposure, amphetamine self-administration and adult dopamine dynamics in dorsal striatum, including response to amphetamine challenge, in male Wistar rats. Ethanol (2 g/kg) or water was administered intragastrically in an episodic binge-like regimen (three continuous days/week) between 4 and 9 weeks of age (i.e. post-natal days 28-59). In adulthood, animals were divided into two groups. In the first, dorsal striatal potassium-evoked dopamine release was examined via chronoamperometry, in the basal state and after a single amphetamine challenge (2 mg/kg, i.v.). In the second, amphetamine self-administration behaviour was studied (i.e. fixed and progressive ratio) before chronoamperometric analysis was conducted as described above. Adolescent ethanol exposure suppressed locally evoked dopamine response after amphetamine challenge in adulthood, whereas in the basal state, no differences in dopamine dynamics were detected. Ethanol-exposed animals showed no differences in adult amphetamine self-administration behaviour but an abolished effect on dopamine removal in response to a single amphetamine challenge after self-administration. Amphetamine challenges in adult rats revealed differences in in vivo dopamine function after adolescent ethanol exposure. The attenuated drug response in ethanol-exposed animals may affect habit formation and contribute to increased risk for substance use disorders as a consequence of adolescent ethanol.
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| 10. |
- Granholm, Linnea
(författare)
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Neurobiological Consequences of Social Conditions and Alcohol Exposure in Adolescent rats
- 2015
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Licentiatavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Adolescence represents a time of extensive reorganisation and maturation of brain circuits involved in emotions, motivation and cognition and it is a period particular sensitive for external stimuli. External stimuli can be both socio-environmental factors and exposure to exogenous compounds such as drugs of abuse (e.g. alcohol). If these stimuli are of an adverse nature the probability of develop neuropsychiatric diseases or addiction is increased. To study the neurobiological consequences of adverse events during adolescence animal models are crucial since they give the opportunity of providing an environment where the exposure of the stimuli is controlled and also enable a detailed analysis of the effects in the brain. The overall aim of in this thesis was to investigate how environmental factors, social conditions or alcohol exposure, during adolescence affect the brain and/or drug-taking in rats. Rats are very sensitive for dis- turbances in their social conditions and to induce an adverse social environment, early adolescent rats where single-housed for either a short or prolonged time. A short period of single housing induced an acute stress response and increased levels of nociceptin/orphanin FQ in brain areas associated with stress. Prolonged single housing reduced the levels of Met-enkephalin-Arg6Phe7 in several brain areas. Rats exposed to alcohol during adolescence had an altered dopamine response in dorsal striatum after an am- phetamine challenge but displayed similar amphetamine intake-behaviour as water controls. However, animals exposed to a combination of adolescent alcohol exposure and subsequent amphetamine intake had a more efficient removal of dopamine in dorsal striatum after an amphetamine challenge. This thesis demonstrates how two different environmental stimuli are able to alter the neurobiology in adolescent rats. The results further support the notion that environmental conditions are of importance for normal brain maturation and provide new evidence that endogenous opioids are severely affected by social dis- turbances during adolescence. Furthermore, additional information is provided to the existing literature of how alcohol exposure during adolescence affects dopamine dynamics and drug-taking behaviour. In the literature, the majority of the studies of adolescent alcohol exposure have focused on the nucleus accum- bens, a brain area important in the processing of rewards. The results herein provide evidence that dorsal striatum, a brain area involved in the transition into habitual drug use is also affected by adolescent alco- hol exposure. An altered drug response in dorsal striatum may affect habit formation and contribute to a heightened susceptibility for high drug consumption later in life.
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