| 1. |
- Abramsson, Alexandra, 1973, et al.
(författare)
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No Association of LOXL1 Gene Polymorphisms with Alzheimer's Disease
- 2011
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Ingår i: NeuroMolecular Medicine. - : Springer Science and Business Media LLC. - 1535-1084 .- 1559-1174. ; 13:2, s. 160-166
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Tidskriftsartikel (refereegranskat)abstract
- Aggregation of amyloid-beta is one of the major characteristics in brains of patients with Alzheimer's disease (AD). Although several mechanisms behind the formation of such aggregates have been suggested the regulatory factors are still unknown. The present study aimed at investigating the association of lysyl oxidase-like 1 (LOXL1) polymorphisms with AD diagnosis and cerebrospinal fluid biomarkers (CSF) for the disease. Proteins of the lysyl oxidase (LOX) family are involved in cross-linking extracellular matrix proteins to insoluble fibers and have been associated with neurodegenerative diseases including AD. Genetic polymorphisms in LOXL1 (rs1048661, rs3825942, and rs2165241) have been linked to exfoliation syndrome and exfoliation glaucoma, conditions that have shown association with AD. The polymorphisms were genotyped by Taqman allelic discrimination in a study sample including AD patients (n = 318) and controls (n = 575). In a subgroup of the population, the polymorphisms were analyzed in relation to APOE epsilon 4 genotype and to CSF (T-tau, P-tau, and A beta(1-42)). No evidence for associations of these polymorphisms with risk for AD or any of the studied CSF biomarkers measured was found. These results do not support LOXL1 as being a major risk gene for AD.
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| 2. |
- Dickson, Suzanne L., 1966, et al.
(författare)
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The role of the central ghrelin system in reward from food and chemical drugs.
- 2011
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Ingår i: Molecular and cellular endocrinology. - : Elsevier BV. - 1872-8057 .- 0303-7207. ; 340:1, s. 80-87
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Forskningsöversikt (refereegranskat)abstract
- Here we review recent advances that identify a role for the central ghrelin signalling system in reward from both natural rewards (such as food) and artificial rewards (that include alcohol and drugs of abuse). Whereas ghrelin emerged as a stomach-derived hormone involved in energy balance, hunger and meal initiation via hypothalamic circuits, it now seems clear that it also has a role in motivated reward-driven behaviours via activation of the so-called "cholinergic-dopaminergic reward link". This reward link comprises a dopamine projection from the ventral tegmental area (VTA) to the nucleus accumbens together with a cholinergic input, arising primarily from the laterodorsal tegmental area. Ghrelin administration into the VTA or LDTg activates the "cholinergic-dopaminergic" reward link, suggesting that ghrelin may increase the incentive value of motivated behaviours such as reward-seeking behaviour ("wanting" or "incentive motivation"). Further, direct injection of ghrelin into the brain ventricles or into the VTA increases the consumption of rewarding foods as well as alcohol in mice and rats. Studies in rodents show beneficial effects of ghrelin receptor (GHS-R1A) antagonists to suppress the intake of palatable food, to reduce preference for caloric foods, to suppress food reward and motivated behaviour for food. They have also been shown to reduce alcohol consumption, suppress reward induced by alcohol, cocaine and amphetamine. Furthermore, variations in the GHS-R1A and pro-ghrelin genes have been associated with high alcohol consumption, smoking and increased weight gain in alcohol dependent individuals as well as with bulimia nervosa and obesity. Thus, the central ghrelin signalling system interfaces neurobiological circuits involved in reward from food as well as chemical drugs; agents that directly or indirectly suppress this system emerge as potential candidate drugs for suppressing problematic over-eating that leads to obesity as well as for the treatment of substance use disorder.
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| 3. |
- Jerlhag, Elisabeth, 1978, et al.
(författare)
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Requirement of central ghrelin signaling for alcohol reward.
- 2009
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Ingår i: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 1091-6490. ; 106:27, s. 11318-23
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Tidskriftsartikel (refereegranskat)abstract
- The stomach-derived hormone ghrelin interacts with key CNS circuits regulating energy balance and body weight. Here we provide evidence that the central ghrelin signaling system is required for alcohol reward. Central ghrelin administration (to brain ventricles or to tegmental areas involved in reward) increased alcohol intake in a 2-bottle (alcohol/water) free choice limited access paradigm in mice. By contrast, central or peripheral administration of ghrelin receptor (GHS-R1A) antagonists suppressed alcohol intake in this model. Alcohol-induced locomotor stimulation, accumbal dopamine release and conditioned place preference were abolished in models of suppressed central ghrelin signaling: GHS-R1A knockout mice and mice treated with 2 different GHS-R1A antagonists. Thus, central ghrelin signaling, via GHS-R1A, not only stimulates the reward system, but is also required for stimulation of that system by alcohol. Our data suggest that central ghrelin signaling constitutes a potential target for treatment of alcohol-related disorders.
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| 4. |
- Jerlhag, Elisabeth, 1978, et al.
(författare)
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The alcohol-induced locomotor stimulation and accumbal dopamine release is suppressed in ghrelin knockout mice.
- 2011
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Ingår i: Alcohol. - : Elsevier BV. - 1873-6823 .- 0741-8329. ; 45:4, s. 341-347
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Tidskriftsartikel (refereegranskat)abstract
- Ghrelin, the first endogenous ligand for the type 1A growth hormone secretagogue receptor (GHS-R1A), plays a role in energy balance, feeding behavior, and reward. Previously, we showed that pharmacologic and genetic suppression of the GHS-R1A attenuates the alcohol-induced stimulation, accumbal dopamine release, and conditioned place preference as well as alcohol consumption in mice, implying that the GHS-R1A is required for alcohol reward. The present study further elucidates the role of ghrelin for alcohol-induced dopamine release in nucleus accumbens and locomotor stimulation by means of ghrelin knockout mice. We found that the ability of alcohol to increase accumbal dopamine release in wild-type mice is not observed in ghrelin knockout mice. Furthermore, alcohol induced a locomotor stimulation in the wild-type mice and ghrelin knockout mice; however, the locomotor stimulation in homozygote mice was significantly lower than in the wild-type mice. The present series of experiments suggest that endogenous ghrelin may be required for the ability of alcohol to activate the mesolimbic dopamine system.
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| 5. |
- Landgren, Sara, 1980, et al.
(författare)
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A novel ARC gene polymorphism is associated with reduced risk of Alzheimer's disease
- 2012
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Ingår i: Journal of Neural Transmission. - : Springer Science and Business Media LLC. - 0300-9564 .- 1435-1463. ; 119:7, s. 833-842
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Tidskriftsartikel (refereegranskat)abstract
- Alzheimer's disease (AD) is the most common neurodegenerative disease, and is clinically characterized by cognitive disturbances and the accumulation of the amyloid beta (A beta) peptides in plaques in the brain. Recent studies have shown the links between AD and the immediate-early gene Arc (activity-regulated cytoskeleton-associated protein), involved in synaptic plasticity and memory consolidation. For example, AD mouse models show a decreased expression of Arc mRNA in the brain. In additional, acute A beta application to brain slices leads to a widespread ARC protein diffusion, unlike the normal defined localization to synapses. In this study, we investigated genetic variation in human ARC and the risk of developing AD. To this end, we genotyped 713 subjects diagnosed with AD and 841 controls without dementia. ARC was sequenced in a group of healthy individuals, and seven previously known SNPs and three novel SNPs were identified. Two of the newly found SNPs were intronic and one, +2852(G/A), was located in the 3'UTR. Three tag SNPs were selected, including the novel SNP +2852(G/A), to relate to risk of AD, Mini Mental State Examination (MMSE) scores and cerebrospinal fluid (CSF) biomarker levels of total tau (T-tau), hyperphosphorylated tau181 (P-tau(181)) and A beta(1-42). The AA genotype of the newly found 3'-UTR SNP +2852(A/G), was associated with a decreased risk of AD (p (c) = 0.005; OR = 0.74; 95 % CI: 0.61-0.89). No associations of single SNPs or haplotypes with MMSE score or CSF biomarkers were found. Here we report a novel ARC SNP associated with a reduced risk of developing AD. To our knowledge, this is the first study associating a gene variant of ARC with any disease. The location of the SNP within the 3'UTR indicates that dendritic targeting of ARC mRNA could be involved in the molecular mechanisms underlying this protective function. However, further investigation of the importance of this SNP for ARC function, ARC processing and the pathology of AD is needed.
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| 6. |
- Landgren, Sara, 1980, et al.
(författare)
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Association of nAChR gene haplotypes with heavy alcohol use and body mass.
- 2009
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Ingår i: Brain research. - : Elsevier BV. - 1872-6240 .- 0006-8993. ; 1305 Suppl
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Tidskriftsartikel (refereegranskat)abstract
- Co-occurring alcohol and nicotine dependence is common, as is alcohol use disorder and overeating. However, major risk genes for these disorders need to be identified. Certain subtypes of the nicotinic acetylcholine receptors in the ventral tegmental area (a reward node) have preclinically been shown to be important for alcohol reward. Therefore the aim was to investigate nicotine receptor subunit genes in a haplotype study of alcohol use. This study includes a Spanish population (n=417) of three groups based on their alcohol consumption; abstainers (n=142), moderate (<280 g/week, n=111) and heavy drinkers (>280 g/week, n=164). 20 tag SNPs in five nicotine receptor subunit genes (CHRNA3, 4, and 6; CHRNB2 and 3) were genotyped and analysed for single marker and haplotype associations. Two haplotypes of the CHRNA6 (CCCC and TCGA) were associated with heavy alcohol consumption (p=0.004 and p=0.035 respectively) and with increased alcohol intake (p=0.004) for the CCCC haplotype compared to non-carriers of these haplotypes. Moreover, one haplotype of the CHRNA4 (GGTG) was associated with increased body weight as compared to non-carriers of this haplotype, especially in the heavy consumers of alcohol (p=0.004).The present findings are the first to disclose a haplotype association between the CHRNA6 gene and heavy alcohol use as well as an association of the CHRNA4 gene with increased body mass in heavy consumers of alcohol. Taken together with previous preclinical data, this targets the nicotinic acetylcholine receptors for development of novel treatment strategies of addictive behaviours, and, more specifically, of a subgroup of individuals with co-morbid alcohol use disorder and overeating.
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| 7. |
- Landgren, Sara, 1980, et al.
(författare)
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Association of Pro-Ghrelin and GHS-R1A Gene Polymorphisms and Haplotypes With Heavy Alcohol Use and Body Mass.
- 2008
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Ingår i: Alcoholism, clinical and experimental research. - : Wiley. - 1530-0277 .- 0145-6008. ; 32:12, s. 2054-2061
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Tidskriftsartikel (refereegranskat)abstract
- Background: Ghrelin, an orexigenic peptide, acts on growth hormone secretagogue receptors (GHS-R1A), expressed in the hypothalamus as well as in important reward nodes such as the ventral tegmental area. Interestingly, ghrelin has been found to activate an important part of the reward systems, i.e., the cholinergic-dopaminergic reward link. Additionally, the rewarding and neurochemical properties of alcohol are, at least in part, mediated via this reward link. There is comorbidity between alcohol dependence and eating disorders. Thus, plasma levels of ghrelin are altered in patients with addictive behaviors such as alcohol and nicotine dependence and in binge eating disorder. This overlap prompted as to investigate the pro-ghrelin and GHS-R1A genes in a haplotype analysis of heavy alcohol-using individuals. Methods: A total of 417 Spanish individuals (abstainers, moderate, and heavy alcohol drinkers) were investigated in a haplotype analysis of the pro-ghrelin and GHS-R1A genes. Tag SNPs were chosen using HapMap data and the Tagger and Haploview softwares. These SNPs were then genotyped using TaqMan Allelic Discrimination. Results: SNP rs2232165 of the GHS-R1A gene was associated with heavy alcohol consumption and SNP rs2948694 of the same gene as well as haplotypes of both the pro-ghrelin and the GHS-R1A genes were associated with body mass in heavy alcohol consuming individuals. Conclusions: The present findings are the first to disclose an association between the pro-ghrelin and GHS-R1A genes and heavy alcohol use, further strengthening the role of the ghrelin system in addictive behaviors and brain reward.
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| 8. |
- Landgren, Sara, 1980, et al.
(författare)
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Expression of the gene encoding the ghrelin receptor in rats selected for differential alcohol preference.
- 2011
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Ingår i: Behavioural brain research. - : Elsevier BV. - 1872-7549 .- 0166-4328. ; 221:1, s. 182-8
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms involved in alcohol use disorder, a chronic relapsing brain disorder, are complex and involve various signalling systems in the brain. Recently, the orexigenic peptide ghrelin was shown to be required for alcohol-induced reward, an effect mediated via ghrelin receptors, GHS-R1A, at the level of the cholinergic-dopaminergic reward link. Moreover, ghrelin increases and GHR-R1A antagonists reduce moderate alcohol consumption in mice, and a single nucleotide polymorphism in the GHS-R1A gene has been associated with high alcohol consumption in humans. Therefore, GHS-R1A gene expression and alcohol intake were investigated in high, AA (Alko, Alcohol), versus low, ANA (Alko, Non-Alcohol), alcohol consuming rats as well as in Wistar rats. In the AA and ANA rats plasma ghrelin levels were also measured. GHS-R1A gene expression was increased in AA compared to ANA rats in nucleus accumbens, ventral tegmental area, amygdala, prefrontal cortex and hippocampus. A similar trend was observed in the ventral tegmental area of Wistar rats consuming high amounts of alcohol. Furthermore, the AA rats had significantly smaller reduction of plasma ghrelin levels over time, after several weeks of alcohol exposure, than had the ANA rats. The present study provides further evidence for that the ghrelin signalling system, in particular at the level of the mesocortocolimbic dopamine system, is involved in alcohol consumption, and thus possibly contributes to alcohol use disorder. Therefore the GHS-R1A may constitute a novel candidate for development of new treatment strategies for alcohol dependence.
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| 9. |
- Landgren, Sara, 1980, et al.
(författare)
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Genetic variation of the ghrelin signaling system in females with severe alcohol dependence
- 2010
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Ingår i: Alcoholism: Clinical and Experimental Research. - : Wiley. - 0145-6008 .- 1530-0277. ; 34:9, s. 1519-1524
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Tidskriftsartikel (refereegranskat)abstract
- INTRODUCTION: Central ghrelin signaling is required for the rewarding effects of alcohol in mice. Because ghrelin is implied in other addictive behaviors such as eating disorders and smoking, and because there is co-morbidity between these disorders and alcohol dependence, the ghrelin signaling system could be involved in mediating reward in general. Furthermore, in humans, single nucleotide polymorphisms (SNPs) and haplotypes of the pro-ghrelin gene (GHRL) and the ghrelin receptor gene (GHSR) have previously been associated with increased alcohol consumption and increased body weight. Known gender differences in plasma ghrelin levels prompted us to investigate genetic variation of the ghrelin signaling system in females with severe alcohol dependence (n = 113) and in a selected control sample of female low-consumers of alcohol from a large cohort study in southwest Sweden (n = 212). METHODS: Six tag SNPs in the GHRL (rs696217, rs3491141, rs4684677, rs35680, rs42451, and rs26802) and four tag SNPs in the GHSR (rs495225, rs2232165, rs572169, and rs2948694) were genotyped in all individuals. RESULTS: We found that one GHRL haplotype was associated with reports of paternal alcohol dependence as well as with reports of withdrawal symptoms in the female alcohol-dependent group. Associations with 2 GHSR haplotypes and smoking were also shown. One of these haplotypes was also negatively associated with BMI in controls, while another haplotype was associated with having the early-onset, more heredity-driven, type 2 form of alcohol dependence in the patient group. CONCLUSION: Taken together, the genes encoding the ghrelin signaling system cannot be regarded as major susceptibility genes for female alcohol dependence, but is, however, involved in paternal heritability and may affect other reward- and energy-related factors such as smoking and BMI.
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| 10. |
- Landgren, Sara, 1980, et al.
(författare)
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Ghrelin receptor (GHS-R1A) antagonism suppresses both operant alcohol self-administration and high alcohol consumption in rats.
- 2012
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Ingår i: Addiction biology. - : Wiley. - 1355-6215. ; 17:1, s. 86-94
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Tidskriftsartikel (refereegranskat)abstract
- The mechanisms involved in alcohol use disorders are complex. It has been shown that ghrelin is an important signal for the control of body weight homeostasis, preferably by interacting with hypothalamic circuits, as well as for drug reward by activating the mesolimbic dopamine system. The ghrelin receptor (GHS-R1A) has been shown to be required for alcohol-induced reward. Additionally, ghrelin increases and GHR-R1A antagonists reduce moderate alcohol consumption in mice, and a single nucleotide polymorphism in the GHS-R1A gene has been associated with high alcohol consumption in humans. However, the role of central ghrelin signaling in high alcohol consumption is not known. Therefore, the role of GHS-R1A in operant self-administration of alcohol in rats as well as for high alcohol consumption in Long-Evans rats and in alcohol preferring [Alko alcohol (AA)] rats was studied here. In the present study, the GHS-R1A antagonist, JMV2959, was found to reduce the operant self-administration of alcohol in rats and to decrease high alcohol intake in Long-Evans rats as well as in AA rats. These results suggest that the ghrelin receptor signaling system, specifically GHS-R1A, is required for operant self-administration of alcohol and for high alcohol intake in rats. Therefore, the GHS-R1A may be a therapeutic target for treatment of addictive behaviors, such as alcohol dependence.
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