| 1. |
- Bohlooly-Yeganeh, Mohammad, 1966, et al.
(author)
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Enhanced spontaneous locomotor activity in bovine GH transgenic mice involves peripheral mechanisms
- 2001
-
In: Endocrinology. ; 142:10, s. 4560-4567
-
Journal article (peer-reviewed)abstract
- Clinical and experimental studies indicate a role for GH in mechanisms related to anhedonia/hedonia, psychic energy, and reward. Recently we showed that transgenic mice with general overexpression of bovine GH display increased spontaneous locomotor activity. In the present study, we investigated whether this behavioral change is owing to a direct action of GH in the central nervous system or to peripheral GH actions. A transgenic construct, containing the glial fibrillary acidic protein promoter directing specific expression of bovine GH to the central nervous system, was designed. The central nervous system-specific expression of bovine GH in the glial fibrillary acidic protein-bovine GH transgenic mice was confirmed, but no effect on spontaneous locomotor activity was observed. Serum bovine GH levels were increased in glial fibrillary acidic protein-bovine GH transgenic mice but clearly lower than in transgenic mice with general overexpression of bovine GH. In contrast to the transgenic mice with general overexpression of bovine GH, glial fibrillary acidic protein-bovine GH mice did not display any difference in serum IGF-I levels. The levels of free T(3) and the conversion of the free T(4) to free T(3) were only increased in transgenic mice with general overexpression of bovine GH, but serum corticosterone levels were similarly increased in both transgenic models. These results suggest that free T(3) and/or IGF-I, affecting dopamine and serotonin systems in the central nervous system, may mediate the enhanced locomotor activity observed in transgenic mice with general overexpression of bovine GH.
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| 2. |
- Brkic, Sejla, et al.
(author)
-
A family history of Type 1 alcoholism differentiates alcohol consumption in high cortisol responders to stress
- 2015
-
In: Pharmacology Biochemistry and Behavior. - : Elsevier BV. - 0091-3057. ; 130, s. 59-66
-
Journal article (peer-reviewed)abstract
- Background: The differentiation between high and low cortisol responders to stress is of interest in determining the risk factors which may, along with genetic vulnerability, influence alcohol intake. Study 1: Methods: Thirty-two healthy volunteers, family history positive to alcoholism (FHP, n = 16) and family history negative (FUN, n = 16) attended two laboratory sessions during which alcohol or placebo was offered. Results: There were no differences in consumption of alcohol or placebo between FHP and FHN subjects. Study 2: Methods: Fifty-eight healthy social drinkers, FHP (n = 27) and FUN (n = 31) attended two laboratory sessions. They were administered either alcohol or placebo in both sessions they attended. All subjects underwent either a stress task (the Trier Social Stress Test, TSST) or a stress-free period, at two separate occasions, before being offered beverage. After the salivary cortisol analysis, subjects in each group were divided into high (HCR) or low (LCR) cortisol responders. Results: After stress, subjects who were FHP-HCR consumed more alcohol than FHN-HCR. There were no differences in the placebo intake between FHP and FHN subjects regardless of their cortisol response. Conclusions: This result indicates that stress promotes alcohol consumption only in subjects with a family history of Type 1 alcoholism who show an increase in cortisol response to stress. This behaviour is similar to that previously observed in alcohol dependent individuals after stress and thus could represent an endophenotype posing a risk for future development of alcohol use disorders. (C) 2015 The Authors. Published by Elsevier Inc. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
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| 3. |
- Brkic, Sejla, et al.
(author)
-
High cortisol responders to stress show increased sedation to alcohol compared to low cortisol responders: An alcohol dose-response study
- 2016
-
In: Pharmacology Biochemistry and Behavior. - : Elsevier BV. - 0091-3057. ; 143, s. 65-72
-
Journal article (peer-reviewed)abstract
- Aims: The present study was designed to examine the relationship between high and low cortisol response to an acute stressful situation and the subjective effects after different doses of alcohol, in healthy social drinkers. Method: Sixty-four subjects (32 men and 32 women) participated in one laboratory session. They performed a modified version of the Trier Social Stress Test (TSST) immediately before consumption of either placebo or alcohol (0.2, 0.4 or 0.8 g/kg). Subjects in each dose group were then divided into high (HCR; n = 32) or low (LCR; n = 32) cortisol responders. Primary dependent measures were self-report questionnaires of mood. Results: The HCR reported increased ratings on Sedation on the Biphasic Alcohol Effects Scale (BAES) with increased dose in comparison with the LCR. This increase in sedation also correlated to the increase in cortisol levels. Conclusion: We conclude that a high cortisol response to stress modulates the subjective response to alcohol, dose-dependently. HCR subjects experience increased sedative effects of alcohol after consumption of higher doses of alcohol following stress compared to LCR subjects.
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| 4. |
- Söderpalm, Bo, 1959, et al.
(author)
-
Stressas vi till missbruk?
- 2005
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In: Stress. Ed. Ekman R & Arnetz B. - Lund : Liber. - 9789147052585 ; , s. 181-93
-
Book chapter (other academic/artistic)
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| 5. |
- Söderpalm Gordh, Anna, 1971, et al.
(author)
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Healthy subjects with a family history of alcoholism show increased stimulative subjective effects of alcohol.
- 2011
-
In: Alcoholism, clinical and experimental research. - : Wiley. - 1530-0277 .- 0145-6008. ; 35:8, s. 1426-34
-
Journal article (peer-reviewed)abstract
- Background: Research has shown that subjects with a family history positive (FHP) of alcoholism are at increased risk for alcoholism and that this group reacts differently to alcohol than family history negative (FHN) subjects. These different levels of sensitivity may make FHP persons more likely to consume alcohol. Here, we tested the hypothesis that subjects FHP for type 1 alcoholism (according to Cloninger) are more sensitive than control subjects to the stimulative, properties of alcohol following a single moderate dose of alcohol. Methods: Fifty-one healthy men and women (22 FHP and 29 FHN) participated in 2 laboratory sessions, in which they consumed a beverage containing ethanol (0.6g/kg in juice) or placebo (juice alone) in a randomized order. Primary dependent measures were self-report questionnaires of mood states. Results: Subjects with family history of type 1 alcoholism showed increased stimulative responses and an elevated positive mood state after ethanol compared to controls. Conclusions: At this moderate dose, ethanol increased stimulative subjective responses in individuals who were "family history positive." This enhanced sensitivity could motivate to exaggerated drinking and thereby increase the risk for developing alcoholism.
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| 6. |
- Söderpalm Gordh, Anna, 1971, et al.
(author)
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Stress increases consumption of alcohol in humans with a Type 1 Family History of alcoholism in an experimental laboratory setting
- 2011
-
In: Pharmacology Biochemistry and Behavior. - : Elsevier BV. - 0091-3057. ; 99:4, s. 696-703
-
Journal article (peer-reviewed)abstract
- BACKGROUND: This paper investigates how stress interacts with alcohol consumption in subjects with a family history of alcoholism. One mechanism for increases in alcohol intake may be that stress alters the subjective effects produced by the drug. METHODS: 58 healthy volunteers, divided into two groups of family history positive (FHP) and two groups of family history negative (FHN) participated in two laboratory sessions, in which they performed in one out of two sessions a stress task. Then subjects were allowed to choose up to six additional drinks of ethanol or placebo depending on which session they were randomly assigned to start with. RESULTS: It was found that FHP subjects increased their consumption of alcohol after stress. CONCLUSIONS: It is possible that both stress and alcohol specifically exaggerate the feelings of the reward in the FHP individuals in such way that it may increase the likelihood of consuming more alcohol.
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| 7. |
- Ademar, Karin, et al.
(author)
-
Acamprosate reduces ethanol intake in the rat by a combined action of different drug components
- 2023
-
In: Scientific Reports. - 2045-2322. ; 13:1
-
Journal article (peer-reviewed)abstract
- Alcohol misuse accounts for a sizeable proportion of the global burden of disease, and Campral (R) (acamprosate; calcium-bis-(N-acetylhomotaurinate)) is widely used as relapse prevention therapy. The mechanism underlying its effect has in some studies been attributed to the calcium moiety and not to the N-acetylhomotaurine part of the compound. We recently suggested that the dopamine elevating effect of acamprosate is mediated both by N-acetylhomotaurine and calcium in a glycine receptor dependent manner. Here we aimed to explore, by means of in vivo microdialysis, if our previous study using local administration was functionally relevant and if systemic administration of the sodium salt of N-acetylhomotaurine (sodium acamprosate; 200 mg/kg, i.p.) enhanced the effects of calcium chloride (CaCl2; 73.5 mg/kg, i.p.) on nucleus accumbens (nAc) dopamine and/or taurine levels in male Wistar rats. In addition, we investigated the impact of regular acamprosate and the combination of CaCl(2 )and N-acetylhomotaurine on the alcohol deprivation effect (ADE). Finally, we assessed if N-acetylhomotaurine potentiates the ethanol-intake reducing effect of CaCl(2 )in a two-bottle choice voluntary ethanol consumption model followed by an ADE paradigm. Systemic administration of regular acamprosate, sodium acamprosate and CaCl(2 )all trended to increase nAc dopamine whereas the combination of CaCl(2)and sodium acamprosate produced a significant increase. Sodium acamprosate elevated extracellular taurine levels without additional effects of CaCl2. Ethanol intake was significantly reduced by systemic administration of CaCl(2 )without additional effects of the combination of CaCl(2 )and sodium acamprosate. Both acamprosate and CaCl(2 )combined with sodium acamprosate blocked the ADE following acute treatment. The data presented suggest that CaCl(2 )and N-acetylhomotaurine act in concert on a neurochemical level, but calcium appears to have the predominant effect on ethanol intake.
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| 8. |
- Ademar, Karin, et al.
(author)
-
Sodium acamprosate and calcium exert additive effects on nucleus accumbens dopamine in the rat
- 2022
-
In: Addiction Biology. - : Wiley. - 1355-6215 .- 1369-1600. ; 27:5
-
Journal article (peer-reviewed)abstract
- Acamprosate (Campral (R) - calcium-bis[N-acetylhomotaurinate]) is one of few available pharmacotherapies for individuals suffering from alcohol use disorder. Previously, we suggested that acamprosate reduces ethanol intake by increasing dopamine in the nucleus accumbens (nAc), thereby partly substituting for alcohol's dopamine releasing effect. An experimental study suggested the calcium moiety of acamprosate to be the active component of the drug and to mediate the relapse preventing effect. The aim of the present study was to, by means of reversed in vivo microdialysis, elucidate if the dopamine elevating properties of acamprosate are mediated by N-acetylhomotaurine or by the calcium moiety. Male rats were equipped with a microdialysis probe in the nAc and received acute local treatment with regular acamprosate (CaAcamp 0.5 mM), calcium chloride (CaCl2 0.5 mM), sodium acamprosate (NaAcamp 0.5-1 mM), the glycine receptor (GlyR) antagonist strychnine (Stry 20 mu M), or vehicle. In all experiments, extracellular levels of dopamine and taurine were examined. We found that local perfusion with both CaAcamp and CaCl2 increased dopamine levels in a GlyR-dependent manner. NaAcamp did not influence dopamine levels, but concomitant administration with CaCl2 resulted in an additive dopamine output compared to the drugs administrated alone. We also found CaAcamp and the combination of CaCl2 and NaAcamp to increase accumbal taurine levels, suggesting that CaAcamp may act indirectly on GlyRs via taurine release. The present results indicate that both N-acetylhomotaurine and the calcium moiety of acamprosate have dopamine elevating properties within the nAc and that, in this respect, these substances are beneficial in combination.
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| 9. |
- Adermark, Louise, 1974, et al.
(author)
-
Acute and chronic modulation of striatal endocannabinoid-mediated plasticity by nicotine.
- 2019
-
In: Addiction biology. - : Wiley. - 1369-1600 .- 1355-6215. ; 24:3, s. 355-363
-
Journal article (peer-reviewed)abstract
- The endocannabinoid (eCB) system modulates several phenomena related to addictive behaviors, and drug-induced changes in eCB signaling have been postulated to be important mediators of physiological and pathological reward-related synaptic plasticity. Here, we studied eCB-mediated long-term depression (eCB-LTD) in the dorsolateral striatum, a brain region critical for acquisition of habitual and automatic behavior. We report that nicotine differentially affects ex vivo eCB signaling depending on previous exposure in vivo. In the nicotine-naïve brain, nicotine facilitates eCB-signaling and LTD, whereas tolerance develops to this facilitating effect after subchronic exposure in vivo. In the end, a progressive impairment of eCB-induced LTD is established after protracted withdrawal from nicotine. Endocannabinoid-LTD is reinstated 6months after the last drug injection, but a brief period of nicotine re-exposure is sufficient to yet again impair eCB-signaling. LTD induced by the cannabinoid 1 receptor agonist WIN55,212-2 is not affected, suggesting that nicotine modulates eCB production or release. Nicotine-induced facilitation of eCB-LTD is occluded by the dopamine D2 receptor agonist quinpirole, and by the muscarinic acetylcholine receptor antagonist scopolamine. In addition, the same compounds restore eCB-LTD during protracted withdrawal. Nicotine may thus modulate eCB-signaling by affecting dopaminergic and cholinergic neurotransmission in a long-lasting manner. Overall, the data presented here suggest that nicotine facilitates eCB-LTD in the initial phase, which putatively could promote neurophysiological and behavioral adaptations to the drug. Protracted withdrawal, however, impairs eCB-LTD, which may influence or affect the ability to maintain cessation.
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| 10. |
- Adermark, Louise, 1974, et al.
(author)
-
Age-contingent influence over accumbal neurotransmission and the locomotor stimulatory response to acute and repeated administration of nicotine in Wistar rats
- 2015
-
In: Neuropharmacology. - : Elsevier BV. - 0028-3908. ; 97, s. 104-112
-
Journal article (peer-reviewed)abstract
- Nicotine addiction is one of the leading contributors to the global burden of disease, and early onset smokers report a more severe addiction with lower chance of cessation than those with a late onset. Preclinical research supports an age-dependent component to the rewarding and reinforcing properties of nicotine, and the aim of this study was to. define behavioral adaptations and changes in accumbal neurotransmission that arise over 15 days of intermittent nicotine treatment (0.36 mg/kg/day) in rats of three different ages (5 weeks, 10 weeks, 36 weeks old). Repeated treatment increased the locomotor stimulatory response to nicotine in all age groups, but significantly faster in the two younger groups. In addition, nicotine decreased rearing activity in a way that sustained even after repeated administration in aged rats but not in the younger age groups. Electrophysiological field potential recordings revealed a decline in input/output function in the nucleus accumbens (NAc) of animals intermittently treated with nicotine starting at 5 weeks of age, but not in older animals. In drug naive rats, acute administration of nicotine modulated both accumbal dopamine output and excitatory transmission in a partially age dependent manner. Fifteen days of intermittent nicotine treatment did not alter the acute effect displayed by nicotine on dopamine levels or evoked field potentials. The data presented here show that both acute and repeated nicotine administration modulates accumbal neurotransmission and behavior in an age-contingent manner and that these age-dependent differences could reflect important neurobiological underpinnings associated with the increased vulnerability for nicotine-addiction in adolescents. (C) 2015 Elsevier Ltd. All rights reserved.
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| 11. |
- Adermark, Louise, 1974, et al.
(author)
-
Astrocytes modulate extracellular neurotransmitter levels and excitatory neurotransmission in dorsolateral striatum via dopamine D2 receptor signaling
- 2022
-
In: Neuropsychopharmacology. - : Springer Science and Business Media LLC. - 0893-133X .- 1740-634X. ; 47:8, s. 1493-1502
-
Journal article (peer-reviewed)abstract
- Astrocytes provide structural and metabolic support of neuronal tissue, but may also be involved in shaping synaptic output. To further define the role of striatal astrocytes in modulating neurotransmission we performed in vivo microdialysis and ex vivo slice electrophysiology combined with metabolic, chemogenetic, and pharmacological approaches. Microdialysis recordings revealed that intrastriatal perfusion of the metabolic uncoupler fluorocitrate (FC) produced a robust increase in extracellular glutamate levels, with a parallel and progressive decline in glutamine. In addition, FC significantly increased the microdialysate concentrations of dopamine and taurine, but did not modulate the extracellular levels of glycine or serine. Despite the increase in glutamate levels, ex vivo electrophysiology demonstrated a reduced excitability of striatal neurons in response to FC. The decrease in evoked potentials was accompanied by an increased paired pulse ratio, and a reduced frequency of spontaneous excitatory postsynaptic currents, suggesting that FC depresses striatal output by reducing the probability of transmitter release. The effect by FC was mimicked by chemogenetic inhibition of astrocytes using G(i)-coupled designer receptors exclusively activated by designer drugs (DREADDs) targeting GFAP, and by the glial glutamate transporter inhibitor TFB-TBOA. Both FC- and TFB-TBOA-mediated synaptic depression were inhibited in brain slices pre-treated with the dopamine D2 receptor antagonist sulpiride, but insensitive to agents acting on presynaptic glutamatergic autoreceptors, NMDA receptors, gap junction coupling, cannabinoid 1 receptors, mu-opioid receptors, P2 receptors or GABA(A) receptors. In conclusion, our data collectively support a role for astrocytes in modulating striatal neurotransmission and suggest that reduced transmission after astrocytic inhibition involves dopamine.
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| 12. |
- Adermark, Louise, 1974, et al.
(author)
-
Astrocytic Regulation of Endocannabinoid-Dependent Synaptic Plasticity in the Dorsolateral Striatum
- 2024
-
In: INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES. - 1661-6596 .- 1422-0067. ; 25:1
-
Journal article (peer-reviewed)abstract
- Astrocytes are pivotal for synaptic transmission and may also play a role in the induction and expression of synaptic plasticity, including endocannabinoid-mediated long-term depression (eCB-LTD). In the dorsolateral striatum (DLS), eCB signaling plays a major role in balancing excitation and inhibition and promoting habitual learning. The aim of this study was to outline the role of astrocytes in regulating eCB signaling in the DLS. To this end, we employed electrophysiological slice recordings combined with metabolic, chemogenetic and pharmacological approaches in an attempt to selectively suppress astrocyte function. High-frequency stimulation induced eCB-mediated LTD (HFS-LTD) in brain slices from both male and female rats. The metabolic uncoupler fluorocitrate (FC) reduced the probability of transmitter release and depressed synaptic output in a manner that was independent on cannabinoid 1 receptor (CB1R) activation. Fluorocitrate did not affect the LTD induced by the CB1R agonist WIN55,212-2, but enhanced CB1R-dependent HFS-LTD. Reduced neurotransmission and facilitated HFS-LTD were also observed during chemogenetic manipulation using Gi-coupled DREADDs targeting glial fibrillary acidic protein (GFAP)-expressing cells, during the pharmacological inhibition of connexins using carbenoxolone disodium, or during astrocytic glutamate uptake using TFB-TBOA. While pretreatment with the N-methyl-D-aspartate (NMDA) receptor antagonist 2-amino-5-phosphonopentanoic acid (APV) failed to prevent synaptic depression induced by FC, it blocked the facilitation of HFS-LTD. While the lack of tools to disentangle astrocytes from neurons is a major limitation of this study, our data collectively support a role for astrocytes in modulating basal neurotransmission and eCB-mediated synaptic plasticity.
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| 13. |
- Adermark, Louise, 1974, et al.
(author)
-
Brain region specific modulation of ethanol-induced depression of GABAergic neurons in the brain reward system by the nicotine receptor antagonist mecamylamine
- 2014
-
In: Alcohol. - : Elsevier BV. - 0741-8329. ; 48:5, s. 455-461
-
Journal article (peer-reviewed)abstract
- The mechanisms underlying ethanol-induced activation of the mesolimbic dopamine system are not fully understood, but increased extracellular dopamine in the nucleus accumbens (nAc) has been shown to involve nicotinic acetylcholine receptors (nAChRs). Basal activity of dopaminergic neurons in the ventral tegmental area (VTA) is under the influence of GABAergic neurotransmission, and the aim of this study was to characterize the involvement of nAChRs in mediating acute ethanol effects on GABAergic activity in subregions of the brain reward system. Multi-electrode in vivo recordings were made in the VTA and nAc of awake and behaving C57BL6/J mice receiving intraperitoneal injections of saline or ethanol (2.0 g/kg), combined with, or without, pre-injection of the non-competitive nAChR antagonist mecamylamine (1.0 mg/kg). Ethanol significantly decreased the activity of quinpirole-insensitive slow-spiking and fast-spiking units in both the VTA and the nAc as compared to saline injection. Pre-treatment with mecamylamine inhibited the rate-inhibiting properties of ethanol in the VTA, but not in the nAc. The data presented here show that ethanol depresses the activity of quinpirole-insensitive, putative GABAergic neurons, in the mesolimbic dopamine system of mice, and that nAChRs contribute to this modulation. This finding, taken together with previous microdialysis studies, supports an involvement of GABAergic neurons and nAChRs in ethanol's interaction with the mesolimbic dopamine system. (C) 2014 The Authors. Published by Elsevier Inc. All rights reserved.
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| 14. |
- Adermark, Louise, 1974, et al.
(author)
-
Ethanol-induced modulation of synaptic output from the dorsolateral striatum in rat is regulated by cholinergic interneurons.
- 2011
-
In: Neurochemistry international. - : Elsevier BV. - 1872-9754 .- 0197-0186. ; 58:6, s. 693-9
-
Journal article (peer-reviewed)abstract
- The striatum is the largest input nucleus to the basal ganglia and associated with reward-based behavior. We assessed whether acute ethanol (EtOH) exposure could modulate synaptic efficacy in the dorsolateral striatum of juvenile Wistar rats. Since acute EtOH administration can both increase and decrease the probability of release of different neurotransmitters from synaptic terminals, we used field potential recordings to evaluate the net effect of EtOH on striatal output. We showed that 50mM EtOH but not 20, 80 or 100mM, depresses population spike (PS) amplitude in the dorsolateral striatum. This depression of synaptic output is insensitive to the N-methyl-d-aspartic acid (NMDA) receptor inhibitor DL-2-amino-5-phosphonopentanoic acid (AP-5, 50μM), but is blocked in slices treated with glycine receptor antagonists (strychnine, 1μM; PMBA, 50μM), nicotinic acetylcholine receptor antagonists (mecamylamine, 10μM; methyllycaconitine citrate (MLA), 40nM), or GABA(A) receptor inhibitors (picrotoxin, 100μM; bicuculline, 2μM, 20μM). A long-term facilitation of synaptic output, which is more pronounced in slices from adult Wistar rats, is detected following EtOH washout (50, 80, 100mM). This long-term enhancement of PS amplitude is regulated by cholinergic interneurons and completely blocked by mecamylamine, MLA or the non-selective muscarinic antagonist scopolamine (10μM). Administration of 100mM EtOH significantly depresses PS amplitude in scopolamine-treated slices, suggesting that EtOH exerts dual actions on striatal output that are initiated instantly upon drug wash-on. In conclusion, EtOH modulates striatal microcircuitry and neurotransmission in a way that could be of importance for understanding the intoxicating properties as well as the acute reward sensation of EtOH.
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| 15. |
- Adermark, Louise, 1974, et al.
(author)
-
Implications for glycine receptors and astrocytes in ethanol-induced elevation of dopamine levels in the nucleus accumbens.
- 2011
-
In: Addiction biology. - : Wiley. - 1369-1600 .- 1355-6215. ; 16:1, s. 43-54
-
Journal article (peer-reviewed)abstract
- ABSTRACT Elevated dopamine levels are believed to contribute to the rewarding sensation of ethanol (EtOH), and previous research has shown that strychnine-sensitive glycine receptors in the nucleus accumbens (nAc) are involved in regulating dopamine release and in mediating the reinforcing effects of EtOH. Furthermore, the osmoregulator taurine, which is released from astrocytes treated with EtOH, can act as an endogenous ligand for the glycine receptor, and increase extracellular dopamine levels. The aim of this study was to address if EtOH-induced swelling of astrocytes could contribute to elevated dopamine levels by increasing the extracellular concentration of taurine. Cell swelling was estimated by optical sectioning of fluorescently labeled astrocytes in primary cultures from rat, and showed that EtOH (25-150 mM) increased astrocyte cell volumes in a concentration- and ion-dependent manner. The EtOH-induced cell swelling was inhibited in cultures treated with the Na(+)/K(+)/2Cl(-) cotransporter blocker furosemide (1 mM), Na(+)/K(+)-ATPase inhibitor ouabain (0.1 mM), potassium channel inhibitor BaCl(2) (50 microM) and in cultures containing low extracellular sodium concentration (3 mM). In vivo microdialysis performed in the nAc of awake and freely moving rats showed that local treatment with EtOH enhanced the concentrations of dopamine and taurine in the microdialysate, while glycine and beta-alanine levels were not significantly modulated. EtOH-induced dopamine release was antagonized by local treatment with the glycine receptor antagonist strychnine (20 microM) or furosemide (100 microM or 1 mM). Furosemide also prevented EtOH-induced taurine release in the nAc. In conclusion, our data suggest that extracellular concentrations of dopamine and taurine are interconnected and that swelling of astrocytes contributes to the acute rewarding sensation of EtOH.
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| 16. |
- Adermark, Louise, 1974, et al.
(author)
-
Intermittent ethanol consumption depresses endocannabinoid-signaling in the dorsolateral striatum of rat.
- 2011
-
In: Neuropharmacology. - : Elsevier BV. - 1873-7064 .- 0028-3908. ; https://gup.ub.gu.se/publications/sho61:7, s. 1160-1165
-
Journal article (peer-reviewed)abstract
- Recent research suggests that adaptations elicited by drugs of abuse share common features with traditional learning models, and that drugs of abuse cause long-term changes in behavior by altering synaptic function and plasticity. In this study, endocannabinoid (eCB) signaling in the dorsolateral striatum, a brain region vital for habit formation, was evaluated in acutely isolated brain slices from ethanol (EtOH)-consuming rats and control rats. EtOH-consuming rats had free access to a 20% EtOH solution for three 24hour sessions a week during seven weeks and consumed an average of 3.4g/kg per session. eCB-mediated long-lasting disinhibition (DLL) of population spike (PS) amplitude induced by moderate frequency stimulation was impaired in EtOH-consuming rats, and was not restored by the muscarinic receptor antagonist scopolamine (10μM). The lack of DLL could be linked to a reduced GABA(A) receptor tone, since bicuculline-mediated disinhibition of striatal output was significantly reduced in slices from EtOH-consuming rats. However, eCB signaling induced by high frequency stimulation (HFS) was also impaired in slices from EtOH-consuming rats and isolated control rats. Activation of presynaptic cannabinoid 1 receptors (CB1R) with WIN55,212-2 (250nM, 1μM) significantly modulated PS amplitude in slices from age-matched control rats while slices from EtOH-consuming rats remained unaffected, indicating that eCB signaling is inhibited at a level that is downstream from CB1R activation. Intermittent alcohol intake for seven weeks might thus be sufficient to modulate a presynaptic mechanism that needs to be synergized with CB1R activation for induction of long-term depression (LTD). In conclusion, alcohol consumption inhibits striatal eCB signaling in a way that could be of importance for understanding the neurological underpinnings of addictive behavior.
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| 17. |
- Adermark, Louise, 1974, et al.
(author)
-
Region-specific depression of striatal activity in Wistar rat by modest ethanol consumption over a ten-month period
- 2013
-
In: Alcohol. - : Elsevier BV. - 0741-8329. ; 47:4, s. 289-298
-
Journal article (peer-reviewed)abstract
- The nucleus accumbens (nAc) is the primary target for the mesolimbic dopamine system and a key brain region for the reinforcing effects displayed by drugs of abuse, including ethanol. During the. transition from recreational to compulsive consumption of reinforcing drugs, however, the dorsal striatum seems to be recruited. Understanding how synaptic activity is altered in a sub-region specific manner in the striatum during the course of long-term drug consumption thus could be essential for understanding the long-lasting changes produced by addictive substances, including ethanol. Here we evaluated synaptic activity in the dorsolateral striatum (DLS) and ventral Striatum (nucleus accumbens, nAc) of single-housed Wistar rats consuming water, or water and ethanol, for up to 10 months. Even though ethanol intake was moderate, it was sufficient to decrease input/output function in response to stimulation intensity in the DLS, while recorded population spike (PS) amplitudes in the nAc were unaffected. Striatal disinhibition induced by the GABA(A) receptor antagonist bicuculline had a slower onset in rats that had consumed ethanol for 2 months, and was significantly depressed in slices from rats that had Consumed ethanol for 4 months. Bicuculline-induced disinhibition in the nAc, on the other hand, was not significantly altered by long-term ethanol intake. Changes in PS amplitude induced by taurine or the glycine receptor antagonist strychnine were not significantly altered by ethanol in any brain region. Even though input/output function was not significantly affected by age, there was a significant decline in antagonist-induced disinhibition in brain slices from aged rats. The data presented here suggest that even modest consumption of ethanol is sufficient to alter neurotransmission in the striatum, while synaptic activity appears to be relatively well-preserved in the nAc during the course of long-term ethanol consumption. (C) 2013 Elsevier Inc. All rights reserved.
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| 18. |
- Adermark, Louise, 1974, et al.
(author)
-
Subregion-Specific Modulation of Excitatory Input and Dopaminergic Output in the Striatum by Tonically Activated Glycine and GABA(A) Receptors.
- 2011
-
In: Frontiers in systems neuroscience. - : Frontiers Media SA. - 1662-5137. ; 5
-
Journal article (peer-reviewed)abstract
- The flow of cortical information through the basal ganglia is a complex spatiotemporal pattern of increased and decreased firing. The striatum is the biggest input nucleus to the basal ganglia and the aim of this study was to assess the role of inhibitory GABA(A) and glycine receptors in regulating synaptic activity in the dorsolateral striatum (DLS) and ventral striatum (nucleus accumbens, nAc). Local field potential recordings from coronal brain slices of juvenile and adult Wistar rats showed that GABA(A) receptors and strychnine-sensitive glycine receptors are tonically activated and inhibit excitatory input to the DLS and to the nAc. Strychnine-induced disinhibition of glutamatergic transmission was insensitive to the muscarinic receptor inhibitor scopolamine (10μM), inhibited by the nicotinic acetylcholine receptor antagonist mecamylamine (10μM) and blocked by GABA(A) receptor inhibitors, suggesting that tonically activated glycine receptors depress excitatory input to the striatum through modulation of cholinergic and GABAergic neurotransmission. As an end-product example of striatal GABAergic output in vivo we measured dopamine release in the DLS and nAc by microdialysis in the awake and freely moving rat. Reversed dialysis of bicuculline (50μM in perfusate) only increased extrasynaptic dopamine levels in the nAc, while strychnine administered locally (200μM in perfusate) decreased dopamine output by 60% in both the DLS and nAc. Our data suggest that GABA(A) and glycine receptors are tonically activated and modulate striatal transmission in a partially subregion-specific manner.
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| 19. |
- Adermark, Louise, 1974, et al.
(author)
-
Temporal Rewiring of Striatal Circuits Initiated by Nicotine
- 2016
-
In: Neuropsychopharmacology. - : Springer Science and Business Media LLC. - 0893-133X .- 1740-634X. ; 41:13, s. 3051-3059
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Journal article (peer-reviewed)abstract
- Drug addiction has been conceptualized as maladaptive recruitment of integrative circuits coursing through the striatum, facilitating drug-seeking and drug-taking behavior. The aim of this study was to define temporal neuroadaptations in striatal subregions initiated by 3 weeks of intermittent nicotine exposure followed by protracted abstinence. Enhanced rearing activity was assessed in motor activity boxes as a measurement of behavioral change induced by nicotine (0.36 mg/kg), whereas electrophysiological field potential recordings were performed to evaluate treatment effects on neuronal activity. Dopamine receptor mRNA expression was quantified by qPCR, and nicotine-induced dopamine release was measured in striatal subregions using in vivo microdialysis. Golgi staining was performed to assess nicotine-induced changes in spine density of medium spiny neurons. The data presented here show that a brief period of nicotine exposure followed by abstinence leads to temporal changes in synaptic efficacy, dopamine receptor expression, and spine density in a subregion-specific manner. Nicotine may thus initiate a reorganization of striatal circuits that continues to develop despite protracted abstinence. We also show that the response to nicotine is modulated in previously exposed rats even after 6 months of abstinence. The data presented here suggests that, even though not self-administered, nicotine may produce progressive neuronal alterations in brain regions associated with goal-directed and habitual performance, which might contribute to the development of compulsive drug seeking and the increased vulnerability to relapse, which are hallmarks of drug addiction.
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- Chau, Pei Pei, 1981, et al.
(author)
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Acamprosate's ethanol intake-reducing effect is associated with its ability to increase dopamine
- 2018
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In: Pharmacology Biochemistry and Behavior. - : Elsevier BV. - 0091-3057. ; 175, s. 101-107
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Journal article (peer-reviewed)abstract
- Previous studies indicate that the anti-craving substance acamprosate modulates nucleus accumbens (nAc) dopamine levels via a dopamine-controlling nAc-VTA-nAc neurocircuitry. It was demonstrated that glycine receptors in the nAc are involved both in the dopamine-elevating effect and the ethanol intake-reducing effect of the drug. Here we wanted to explore the interaction of ethanol and acamprosate on nAc dopamine and investigate whether dopaminergic transmission may be related to the ethanol intake-reducing effects. In three separate studies we investigated nAc extracellular dopamine levels by means of in vivo microdialysis after administration of acamprosate and ethanol in 1) naïve rats, 2) rats pre-treated with acamprosate for two days or 3) ethanol medium- and high-preferring rats receiving ten days of acamprosate pre-treatment. In the first two studies, acamprosate elevated dopamine and simultaneously prevented ethanol from further increasing dopamine output. In the third study, long-term acamprosate pre-treatment produced a loss of the ethanol intake-reducing as well as the dopamine-elevating effects of acamprosate, and the dopamine elevating property of ethanol was restored. We suggest that acamprosate may partly substitute for the dopamine-elevating effect of ethanol but once tolerance develops to this effect, the ability to decrease ethanol intake is lost.
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- Chau, Pei Pei, 1981, et al.
(author)
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Glycine Receptors in the Nucleus Accumbens Involved in the Ethanol Intake-Reducing Effect of Acamprosate.
- 2009
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In: Alcoholism, clinical and experimental research. - : Wiley. - 1530-0277 .- 0145-6008.
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Journal article (peer-reviewed)abstract
- Background: We have previously demonstrated that strychnine-sensitive glycine receptors (GlyRs) in the nucleus accumbens (nAc) and nicotinic acetylcholine receptors (nAChRs) in the ventral tegmental area are involved in mediating ethanol (EtOH)-induced elevation of dopamine in the rat mesolimbic dopamine system. This neuronal circuitry was also demonstrated to mediate dopamine elevation in the nAc after both taurine, an endogenous agonist of GlyRs, and acamprosate, a synthetic derivate of homotaurine. The aim of this study was to investigate whether the EtOH intake-reducing effect of acamprosate involves accumbal GlyRs. Methods: For this purpose, we used a voluntary EtOH consumption model where EtOH medium- and high-preferring rats were implanted with guide cannulae in the nAc. The animals received daily injections of acamprosate or 0.9% NaCl before accessing a bottle of 6% EtOH and a bottle of water. After 2 days, a microinjection of strychnine or vehicle preceded the daily systemic injection and bottle-access period. Results: Acamprosate, but not saline, decreased EtOH intake. Pretreatment with Ringer in the nAc did not influence EtOH intake in saline or acamprosate-treated animals. Pretreatment with strychnine had no effect on EtOH intake in saline-treated animals, whereas it completely reversed the EtOH intake-reducing effect of acamprosate. Conclusions: Based on current and previous results, we suggest that acamprosate primarily interacts with accumbal GlyRs and secondarily with ventral tegmental nAChRs, in a similar manner to that previously observed with EtOH and taurine. The interaction between acamprosate and GlyRs does not only influence dopamine output in the nAc but also EtOH consumption, giving further support for our hypothesis that GlyRs are of importance in EtOH reinforcement.
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- Chau, Pei Pei, 1981, et al.
(author)
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Glycine Receptors Involved in Acamprosate's Modulation of Accumbal Dopamine Levels: An In Vivo Microdialysis Study.
- 2009
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In: Alcoholism, clinical and experimental research. - : Wiley. - 1530-0277 .- 0145-6008.
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Journal article (peer-reviewed)abstract
- Background: Glycine receptors (GlyRs) in the nucleus accumbens (nAc) and nicotinic acetylcholine receptors (nAChRs) in the ventral tegmental area (VTA) have been suggested to be involved in the positive reinforcing and dopamine elevating effects of ethanol. Recent studies have also shown that ethanol high-preferring rats substantially decrease their ethanol intake when treated with a glycine transporter 1 inhibitor (ORG 25935). Acamprosate, a drug used for relapse prevention in treatment of alcohol dependence, has also been demonstrated to elevate extracellular dopamine levels in the nAc. However, the underlying mechanism of action of acamprosate is not fully understood. Here we investigated whether acamprosate interferes with a neuronal circuitry that previously has been demonstrated to be involved in the dopamine elevating effects of ethanol and taurine. Methods: In vivo microdialysis in freely moving rats was used to assess accumbal dopamine levels before and during local (nAc) or systemic administration of acamprosate. Results: Perfusion of 0.5 mM acamprosate in the nAc significantly increased dopamine levels. Pretreatment either with 10 muM strychnine in the nAc or 100 muM mecamylamine in the VTA, completely antagonized the acamprosate-induced elevation of accumbal dopamine levels. Also, systemic acamprosate administration elevated accumbal dopamine output, an effect that was abolished by local (nAc) pretreatment with 10 muM strychnine. Conclusions: These results suggest that both systemic and local application of acamprosate elevate extracellular dopamine levels in the nAc by activating accumbal GlyRs, and, secondarily, tegmental nAChRs.
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