| 1. |
- Ademar, Karin, et al.
(författare)
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Acamprosate reduces ethanol intake in the rat by a combined action of different drug components
- 2023
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Ingår i: Scientific Reports. - 2045-2322. ; 13:1
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Tidskriftsartikel (refereegranskat)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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| 2. |
- Ademar, Karin, et al.
(författare)
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Sodium acamprosate and calcium exert additive effects on nucleus accumbens dopamine in the rat
- 2022
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Ingår i: Addiction Biology. - : Wiley. - 1355-6215 .- 1369-1600. ; 27:5
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Tidskriftsartikel (refereegranskat)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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| 3. |
- Adermark, Louise, 1974, et al.
(författare)
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Acute and chronic modulation of striatal endocannabinoid-mediated plasticity by nicotine.
- 2019
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Ingår i: Addiction biology. - : Wiley. - 1369-1600 .- 1355-6215. ; 24:3, s. 355-363
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Tidskriftsartikel (refereegranskat)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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| 4. |
- Adermark, Louise, 1974, et al.
(författare)
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Age-contingent influence over accumbal neurotransmission and the locomotor stimulatory response to acute and repeated administration of nicotine in Wistar rats
- 2015
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Ingår i: Neuropharmacology. - : Elsevier BV. - 0028-3908. ; 97, s. 104-112
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Tidskriftsartikel (refereegranskat)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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| 5. |
- Adermark, Louise, 1974
(författare)
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Astrocyte Function in Alcohol Reward and Addiction
- 2015
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Ingår i: Journal of Alcoholism & Drug Dependence. - : OMICS Publishing Group. - 2329-6488. ; 3
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Glial cells, particularly astrocytes, play essential roles in the regulation of neurotransmission, metabolism, and supply of energy substrates for synaptic transmission. One astrocyte can receive inputs from several hundreds of synapses, and synchronized neuronal activity correlates with astrocyte calcium signaling. Astrocyte pathology is a common feature of ethanol exposure in both humans and animal models, and brief alcohol intake is sufficient to cause long-lasting changes in astrocyte gene expression, activity and proliferation. Recent research also suggests that astrocytes shape the rewarding sensation of ethanol, and might be involved in modulating alcohol consumption. Considering the role of astrocytes in regulating glutamate homeostasis, a crucial component of alcohol abuse disorders, the astrocyte might be an important target for the development of new pharmacological treatments of alcoholism.
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| 6. |
- Adermark, Louise, 1974, et al.
(författare)
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Astrocytes modulate extracellular neurotransmitter levels and excitatory neurotransmission in dorsolateral striatum via dopamine D2 receptor signaling
- 2022
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Ingår i: Neuropsychopharmacology. - : Springer Science and Business Media LLC. - 0893-133X .- 1740-634X. ; 47:8, s. 1493-1502
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Tidskriftsartikel (refereegranskat)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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| 7. |
- Adermark, Louise, 1974, et al.
(författare)
-
Astrocytic Regulation of Endocannabinoid-Dependent Synaptic Plasticity in the Dorsolateral Striatum
- 2024
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Ingår i: INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES. - 1661-6596 .- 1422-0067. ; 25:1
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Tidskriftsartikel (refereegranskat)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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| 8. |
- Adermark, Louise, 1974, et al.
(författare)
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Brain region specific modulation of ethanol-induced depression of GABAergic neurons in the brain reward system by the nicotine receptor antagonist mecamylamine
- 2014
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Ingår i: Alcohol. - : Elsevier BV. - 0741-8329. ; 48:5, s. 455-461
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Tidskriftsartikel (refereegranskat)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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| 9. |
- Adermark, Louise, 1974, et al.
(författare)
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Combined activation of L-type Ca2+ channels and synaptic transmission is sufficient to induce striatal long-term depression.
- 2007
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Ingår i: The Journal of neuroscience : the official journal of the Society for Neuroscience. - 1529-2401. ; 27:25, s. 6781-7
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Tidskriftsartikel (refereegranskat)abstract
- Changes in synaptic strength at striatal synapses, such as long-term depression (LTD), may be involved in striatal-based learning and memory. Several molecular mechanisms have been implicated in striatal LTD, but it is not clear which mechanisms are crucial for LTD induction. We found that the activation of L-type calcium channels by 2,5-dimethyl-4-[2-(phenylmethyl)benzoyl]-1H-pyrrole-3-carboxylic acid methylester (FPL64176), combined with modest postsynaptic depolarization and synaptic activation, is sufficient to induce robust LTD (FPL-LTD). The L-channel activator 1,4-dihydro-2,6-dimethyl-5-nitro-4-[2(trifluoromethyl)phenyl]pyridine-3-carboxylic acid methyl ester (Bay K 8644) has a similar action. FPL-LTD occludes LTD induced by high-frequency stimulation (HFS-LTD) and requires elevated postsynaptic calcium and retrograde endocannabinoid signaling, properties similar to those of HFS-LTD. In contrast, FPL-LTD does not require the activation of metabotropic glutamate receptors (mGluRs), phospholipase C, or dopamine D2 receptors. FPL-LTD induction also requires afferent stimulation. These findings suggest a scenario in which L-type calcium channel activation is a crucial switch for LTD induction, and mGluRs and D2 receptors can be bypassed if this channel is activated.
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| 10. |
- Adermark, Louise, 1974, et al.
(författare)
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Disentangling the Role of Astrocytes in Alcohol Use Disorder
- 2016
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Ingår i: Alcoholism-Clinical and Experimental Research. - : Wiley. - 0145-6008. ; 40:9
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Tidskriftsartikel (refereegranskat)abstract
- Several laboratories recently identified that astrocytes are critical regulators of addiction machinery. It is now known that astrocyte pathology is a common feature of ethanol (EtOH) exposure in both humans and animal models, as even brief EtOH exposure is sufficient to elicit long-lasting perturbations in astrocyte gene expression, activity, and proliferation. Astrocytes were also recently shown to modulate the motivational properties of EtOH and other strongly reinforcing stimuli. Given the role of astrocytes in regulating glutamate homeostasis, a crucial component of alcohol use disorder (AUD), astrocytes might be an important target for the development of next-generation alcoholism treatments. This review will outline some of the more prominent features displayed by astrocytes, how these properties are influenced by acute and long-term EtOH exposure, and future directions that may help to disentangle astrocytic from neuronal functions in the etiology of AUD.
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