1.
Aziz, Abdul Maruf Asif
(författare)
Neuropeptide Receptors as Treatment Targets in Alcohol Use Disorders
2017
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Alcohol use disorder (AUD) is a complex disorder with multiple pathophysiological processes contributing to the initiation, progression and development of the disease state. AUD is a chronic relapsing disease with escalation of alcohol-intake over time in repeated cycles of tolerance, abstinence and relapse and hence, it is very difficult to treat. There are only a few currently available treatments with narrow efficacy and variable patient response. Thus it is important to find new, more effective medications to increase the number of patients who can benefit from pharmacological treatment of AUD.The research presented in this thesis work focuses on the critical involvement of central neuropeptides in alcohol-related behaviors. The overall aim was to evaluate the nociceptin/orphanin FQ (NOP) receptor, the neuropeptide Y (NPY) Y2 receptor and the melanin-concentrating hormone (MCH) receptor 1 as novel and potential pharmacological treatment targets for AUD by testing the NOP receptor agonist SR-8993, the NPY-Y2 receptor antagonist CYM-9840 and the MCH1 receptor antagonist GW803430 in established animal models.In the first study (Paper I), the novel and selective NOP agonist SR-8993 was assessed in rat models of motivation to obtain alcohol and relapse to alcohol seeking behavior using the operant self-administration (SA) paradigm. Firstly, treatment with SR-8993 (1 mg/kg) showed a mildly anxiolytic effect and reversed acute alcohol withdrawal-induced “hangover” anxiety in the elevated plus-maze (EPM). Next, it potently attenuated alcohol SA and motivation to obtain alcohol in the progressive ratio responding (PRR) and reduced both alcohol cue-induced and yohimbine stress-induced reinstatement of alcohol seeking, without affecting the pharmacology and metabolism of alcohol nor other control behaviors. To extend these findings, SR-8993 was evaluated in escalated alcohol-intake in rats. Treatment with SR-8993 significantly suppressed alcohol-intake and preference in rats that were trained to consume high amounts of alcohol in the two-bottle free choice intermittent access (IA) paradigm. SR-8993 also blocked operant SA of alcohol in rats that showed robust escalation in operant alcohol SA following chronic IA exposure to alcohol.In the second study (Paper II), SR-8993 was further evaluated in a model for escalated alcohol-intake induced by long-term IA exposure to alcohol. The effect of previous experience on operant alcohol SA on two-bottle free choice preference drinking was evaluated and sensitivity to treatment with SR-8993 was tested in rats selected for escalated and non-escalated alcohol seeking behavior. We found that rats exposed to the combined SA-IA paradigm showed greater sensitivity to SR-8993 treatment. In addition, acute escalation of alcohol SA after a three-week period of abstinence was completely abolished by pretreatment with SR-8993.In the third study (Paper III), the effects of the novel, small molecule NPY-Y2 antagonist CYM-9840 were tested in operant alcohol SA, PRR which is a model for motivation to work for alcohol and reinstatement of alcohol-seeking behavior. Treatment with CYM-9840 (10 mg/kg) potently attenuated alcohol SA, progressive ratio responding and stress-induced reinstatement using yohimbine as the stressor, while alcohol cue-induced reinstatement was unaffected. Moreover, a range of control behaviors including taste sensitivity, locomotor and pharmacological sensitivity to the sedative effects of alcohol remained unaffected by CYM-9840 pretreatment, indicating that its effects are specific to the rewarding and motivational aspects of alcohol-intake and related behaviors. CYM-9840 also reversed acute alcohol withdrawal-induced “hangover” anxiety measured in the EPM and reduced alcohol-intake in the 4 hour limited access two-bottle free choice preference drinking model.Finally, in the fourth study (Paper IV), the selective MCH1-R antagonist GW803430 was tested in rat models of escalated alcohol-intake. Pretreatment with GW803430 (effective at 10 & 30 mg/kg) dose-dependently reduced alcohol and food-intake in rats that consumed high amounts of alcohol during IA, while it only decreased food-intake in rats that consumed low amounts of alcohol during IA, likely due to a floor effect. Upon protracted abstinence following IA, GW803430 significantly reduced operant alcohol SA and this was associated with adaptations in MCH and MCH1-R gene-expression. In contrast, GW803430 did not affect escalated alcohol SA induced by chronic alcohol vapor exposure and this was accompanied by no change in MCH or MCH1-R gene expression. Overall, these results suggest that the MCH1-R antagonist affects alcohol-intake through regulation of both motivation for caloric-intake and the rewarding properties of alcohol.In conclusion, our results suggest critical roles for these central neuropeptides in the regulation of anxiety and of alcohol reward, making them potential pharmacological targets in the treatment of AUD.
2.
Granholm, Linnea, 1986-
(författare)
Stress, Drugs and Neuroscience : Neurobiological Effects of Social Stressors and Drug Exposure in Young and Adolescent Rats
2018
Doktorsavhandling (övrigt vetenskapligt/konstnärligt) abstract
Experiences early in life or during adolescence modulate neuronal networks in the immature brain and consequently lay the foundation for future susceptibility or resilience towards psychiatric disorders. The objective in this thesis is to understand, in part, how the surrounding environment shapes the brain of a young individual. Three types of negative life events were studied, in an animal model, for their effects on the brain reward system (i.e., endogenous opioids and dopamine) and voluntary drug intake. These were: disruption of maternal care, disruption of interaction with peers, and exposure to drugs. Stress, in the form of maternal separation, altered expression of opioid genes in the dorsal striatum and amygdala, and the response to subsequent alcohol intake on these genes was dependent on early life conditions. Basal levels of endogenous opioids were also dependent on how the animals were housed in early adolescence. Short single housing (30 minutes) caused an acute stress response as evidenced by increased serum corticosterone and nociceptin/orphanin FQ in brain areas associated with stress. A prolonged single housing resulted in a marked decrease of Met-Enk-Arg6-Phe7 (i.e., a marker of enkephalins) in several brain areas. The endogenous opioids were also affected by repeated exposure of ethanol during adolescence; ethanol intoxication increased the accumbal levels of Met-Enk-Arg6-Phe7 and decreased those of β-endorphin. Residual effects of the adolescent ethanol exposure were found in Met-Enk-Arg6-Phe7 levels in the amygdala, ventral tegmental area, and substantia nigra. Furthermore, rats exposed to ethanol as adolescents had alterations in the dopamine dynamics in the dorsal striatum. Both endogenous opioids and dopamine are essential in mediating rewarding properties. Alterations of these systems, caused by environmental disturbances and alcohol exposure, presented herein could explain, in part, the increased susceptibility for alcohol- and substance use disorders later in life.
3.
Björk, Karl, et al.
(författare)
Ethanol-induced activation of AKT and DARPP-32 in the mouse striatum mediated by opioid receptors
2010
Ingår i: Addiction Biology. - : Wiley-Blackwell. - 1355-6215 .- 1369-1600. ; 15:3, s. 299-303
Tidskriftsartikel (refereegranskat) abstract
The reinforcing properties of ethanol are in part attributed to interactions between opioid and dopaminergic signaling pathways, but intracellular mediators of such interactions are poorly understood. Here we report that an acute ethanol challenge induces a robust phosphorylation of two key signal transduction kinases, AKT and DARPP-32, in the striatum of mice. Ethanol-induced AKT phosphorylation was blocked by the opioid receptor antagonist naltrexone but unaffected by blockade of dopamine D2 receptors via sulpiride. In contrast, DARPP-32 phosphorylation was abolished by both antagonists. These data suggest that ethanol acts via two distinct but potentially synergistic striatal signaling cascades. One of these is D2-dependent, while the other is not. These findings illustrate that pharmacology of ethanol reward is likely more complex than that for other addictive drugs.
4.
Björk, Karl, et al.
(författare)
β-Arrestin 2 knockout mice exhibit sensitized dopamine release and increased reward in response to a low dose of alcohol
2013
Ingår i: Psychopharmacology. - : Springer. - 0033-3158 .- 1432-2072. ; 230:3, s. 439-449
Tidskriftsartikel (refereegranskat) abstract
RationaleThe rewarding effects of alcohol have been attributed to interactions between opioid and dopaminergic system within the mesolimbic reward pathway. We have previously shown that ablation of β-arrestin 2 (Arrb2), a crucial regulator of μ-opioid receptor function, attenuates alcohol-induced hyperlocomotion and c-fos activation in the nucleus accumbens.ObjectivesHere, we further investigated the role of Arrb2 in modulating alcohol-induced dopamine (DA) release and conditioned place preference (CPP). We also assessed the functional importance of Arrb2 for μ-opioid receptor surface expression and signaling following an acute alcohol challenge.MethodsAlcohol-evoked (0.375, 0.75, and 1.5 g/kg intraperitoneally) DA release was measured by in vivo microdialysis in the shell of nucleus accumbens. Reward was assessed by the CPP paradigm. Receptor function was assessed by μ-receptor binding and [35S]GTP-γ-S autoradiography.ResultsIn Arrb2 knockout mice accumbal DA levels reach maximum response at a lower dose compared to wild-type (wt) animals. In line with these results, Arrb2 knockout mice display increased CPP for alcohol as compared to wt mice. Finally, Arrb2 mutant mice display increased μ-opioid receptor signaling in the ventral and dorsal striatum and amygdala in response to a low dose of alcohol, indicating impaired desensitization mechanisms in these mice.ConclusionsOur results show that Arrb2 modulates the response to low doses of alcohol on various levels including μ-opioid receptor signaling, DA release, and reward. They also reveal a clear dissociation between the effects of Arrb2 on psychomotor and reward behaviors.
5.
Ciccocioppo, Roberto, et al.
(författare)
Stress-related neuropeptides and alcoholism : CRH, NPY, and beyond
2009
Ingår i: Alcohol. - : Elsevier. - 0741-8329 .- 1873-6823. ; 43:7, s. 491-498
Tidskriftsartikel (refereegranskat) abstract
This article summarizes the proceedings of a symposium held at the conference on "Alcoholism and Stress: A Framework for Future Treatment Strategies" in Volterra, Italy, May 6-9, 2008. Chaired by Markus Heilig and Roberto Ciccocioppo, this symposium offered a forum for the presentation of recent data linking neuropetidergic neurotransmission to the regulation of different alcohol-related behaviors in animals and in humans. Dr. Donald Gehlert described the development of a new corticotrophin-releasing factor receptor 1 antagonist and showed its efficacy in reducing alcohol consumption and stress-induced relapse in different animal models of alcohol abuse. Dr. Andrey Ryabinin reviewed recent findings in his laboratory, indicating a role of the urocortin 1 receptor system in the regulation of alcohol intake. Dr. Annika Thorsell showed data supporting the significance of the neuropeptide Y receptor system in the modulation of behaviors associated with a history of ethanol intoxication. Dr. Roberto Ciccocioppo focused his presentation on the nociceptin/orphanin FQ (N/OFQ) receptors as treatment targets for alcoholism. Finally, Dr. Markus Heilig showed recent preclinical and clinical evidence suggesting that neurokinin 1 antagonism may represent a promising new treatment for alcoholism. Collectively, these investigators highlighted the significance of neuropeptidergic neurotransmission in the regulation of neurobiological mechanisms of alcohol addiction. Data also revealed the importance of these systems as treatment targets for the development of new medication for alcoholism.
6.
Cippitelli, Andrea, et al.
(författare)
Alcohol-induced neurodegeneration, suppression of transforming growth factor-beta, and cognitive impairment in rats : prevention by group II metabotropic glutamate receptor activation
2010
Ingår i: Biological Psychiatry. - : Elsevier. - 0006-3223 .- 1873-2402. ; 67:9, s. 823-830
Tidskriftsartikel (refereegranskat) abstract
BACKGROUND: Glutamatergic neurotransmission has been implicated in mechanisms of alcohol-induced neurodegeneration and cognitive impairment, but the underlying mechanism remains unknown. Here, we examined whether the group II metabotropic glutamate receptor agonist LY379268 prevents neuronal death and learning deficits in a rat model of binge-like exposure to alcohol.METHODS: Following 4-day binge alcohol exposure concurrent with LY379268 or vehicle treatment, Fluoro-Jade B and transforming growth factor-beta (TGF-beta) staining were carried out, and reversal learning in the Morris water maze was assessed.RESULTS: Fluoro-Jade B staining indicating neurodegeneration was most extensive in the ventral hippocampus and the entorhinal cortex (EC). LY379268 was potently neuroprotective in the EC but not in the dentate gyrus of the hippocampus. In parallel, binge alcohol exposure suppressed TGF-beta expression in both the EC and dentate gyrus, whereas LY379268 increased TGF-beta in the EC only. Finally, neuroprotective effects of LY379268 were accompanied by prevention of deficits in spatial reversal learning.CONCLUSIONS: Our data support a neuroprotective role for group II metabotropic glutamate receptor agonists and TGF-beta in alcohol-induced neurodegeneration.
7.
Cippitelli, Andrea, et al.
(författare)
Binge-like ethanol consumption increases corticosterone levels and neurodegneration whereas occupancy of type II glucocorticoid receptors with mifepristone is neuroprotective
2014
Ingår i: Addiction Biology. - : Wiley-Blackwell. - 1355-6215 .- 1369-1600. ; 19:1, s. 27-36
Tidskriftsartikel (refereegranskat) abstract
Excessive ethanol (EtOH) use leads to impaired memory and cognition. Using a rat model of binge-like intoxication, we tested whether elevated corticosterone (Cort) levels contribute to the neurotoxic consequences of EtOH exposure. Rats were adrenalectomized (Adx) and implanted with cholesterol pellets, or cholesterol pellets containing Cort in order to achieve basal, medium, or high blood concentrations of Cort. Intragastric EtOH or an isocaloric control solution was given three times daily for 4 days to achieve blood alcohol levels ranging between 200 and 350 mg/dl. Mean 24-hour plasma levels of Cort were ∼110 and ∼40 ng/ml in intact EtOH-treated and intact control animals, respectively. Basal Cort replacement concentrations in EtOH-treated Adx animals did not exacerbate alcohol-induced neurodegeneration in the hippocampal dentate gyrus (DG) or the entorhinal cortex (EC) as observed by amino-cupric silver staining. In contrast, Cort replacement pellets resulting in plasma Cort levels twofold higher (medium) than normal, or greater than twofold higher (high) in Adx-Cort-EtOH animals increased neurodegeneration. In separate experiments, pharmacological blockade of the Type II glucocorticoid (GC) receptor was initiated with mifepristone (RU38486; 0, 5, 15 mg/kg/day, i.p.). At the higher dose, mifepristone decreased the number of degenerating hippocampal DG cells in binge-EtOH-treated intact animals, whereas, only a trend for reduction was observed in 15 mg/kg/day mifepristone-treated animals in the EC, as determined by fluoro-jade B staining. These results suggest that elevated circulating Cort in part mediates EtOH-induced neurotoxicity in the brain through activation of Type II GC receptors.
8.
Cippitelli, Andrea, et al.
(författare)
Neuropeptide Y (NPY) suppresses yohimbine-induced reinstatement of alcohol seeking
2010
Ingår i: Psychopharmacology. - : Springer. - 0033-3158 .- 1432-2072. ; 208:3, s. 417-426
Tidskriftsartikel (refereegranskat) abstract
INTRODUCTION: Reinstatement of responding to a previously alcohol-associated lever following extinction is an established model of relapse-like behavior and can be triggered by stress exposure. Here, we examined whether neuropeptide Y (NPY), an endogenous anti-stress mediator, blocks reinstatement of alcohol-seeking induced by the pharmacological stressor yohimbine.MATERIALS AND METHODS: NPY [5.0 or 10.0 mug/rat, intracerebroventricularly (ICV)] dose-dependently blocked the reinstatement of alcohol seeking induced by yohimbine (1.25 mg/kg, i.p.) but failed to significantly suppress the maintenance of alcohol self-administration. We then used c-fos expression mapping to examine neuronal activation following treatment with yohimbine or NPY alone or yohimbine following NPY pre-treatment.RESULTS AND DISCUSSION: The analysis was focused on a network of structures previously implicated in yohimbine-induced reinstatement, comprised of central (CeA) and basolateral (BLA) amygdala and the shell of the nucleus accumbens (Nc AccS). Within this network, both yohimbine and NPY potently induced neuronal activation, and their effects were additive, presumably indicating activation of excitatory and inhibitory neuronal populations, respectively.CONCLUSION: These results suggest that NPY selectively suppresses relapse to alcohol seeking induced by stressful events and support the NPY system as an attractive target for the treatment of alcohol addiction.
9.
Cippitelli, Andrea, et al.
(författare)
Pharmacological blockade of corticotropin-releasing hormone receptor 1 (CRH1R) reduces voluntary consumption of high alcohol concentrations in non-dependent Wistar rats
2012
Ingår i: Pharmacology, Biochemistry and Behavior. - : Elsevier. - 0091-3057 .- 1873-5177. ; 100:3, s. 522-529
Tidskriftsartikel (refereegranskat) abstract
BACKGROUND: A dysregulation of the corticotropin-releasing hormone (CRH) system has been implicated in the development of excessive alcohol consumption and dependence. The aim of the present study was to evaluate whether the CRH system is also recruited when non-dependent Wistar rats escalate to high alcohol intake in the intermittent (alternate days) model of drinking.METHODS: We compared intermittent and continuous access to 20% (v/v) alcohol in a two-bottle free choice drinking paradigm. Following a total of twenty 24-hour exposures for every experimental group, we assessed signs of alcohol withdrawal, including anxiety-like behavior and sensitivity to stress. The selective CRH1 receptor (CRH1R) antagonist antalarmin (0, 10, 20 mg/kg, i.p.) was tested on alcohol consumption.RESULTS: Intermittent access to 20% alcohol led non-selected Wistar rats to escalate their voluntary intake to a high and stable level, whereas continuously exposed animals maintained a lower consumption. These groups did not differ in physical withdrawal signs. In addition, no differences were found when anxiogenic-like behavior was studied, neither under basal conditions or following restraint stress. Nevertheless, sensitivity to the treatment with the CRH1R antalarmin was observed since a reduction of 20% alcohol intake was found in both groups of animals regardless of the regimen of alcohol exposure. In addition, antalarmin was effective when injected to animals exposed to intermittent 10% (v/v) alcohol whereas it failed to suppress 10% continuous alcohol intake.CONCLUSIONS: Pharmacological blockade of CRH1R reduced alcohol drinking when sustained high levels of intake were achieved suggesting that the CRH system plays a key role when high doses of ethanol are consumed by non-dependent subjects. This supports the notion that CRH system not only maintains the dependent state but also engages the transition to dependence.
10.
Cippitelli, Andrea, et al.
(författare)
Suppression of alcohol self-administration and reinstatement of alcohol seeking by melanin-concentrating hormone receptor 1 (MCH1-R) antagonism in Wistar rats
2010
Ingår i: Psychopharmacology. - : Springer. - 0033-3158 .- 1432-2072. ; 211:4, s. 367-375
Tidskriftsartikel (refereegranskat) abstract
RATIONALE: Melanin-concentrating hormone (MCH) is involved in regulation of appetitive behaviors as well as emotional reactivity and reward, behavioral domains relevant to alcohol addiction.MATERIALS AND METHODS: We evaluated the effects of the non-peptide MCH1 receptor antagonist, GW803430 [6-(4-chloro-phenyl)-3-[3-methoxy-4-(2-pyrrolidin-1-yl-ethoxy)-phenyl]-3H-thieno[3,2-d]pyrimidin-4-one; 3-30 mg/kg, i.p.] on alcohol-related behaviors in Wistar rats.RESULTS: Ex vivo binding experiments demonstrated that the GW803430 dose range used resulted in high central MCH1 receptor occupancy. Alcohol self-administration was dose-dependently and potently suppressed, by approximately 80% at the highest dose. Reinstatement of alcohol-seeking induced by alcohol-associated cues was essentially eliminated. In contrast, reinstatement induced by footshock stress was not significantly altered. Taste preference for a quinine/saccharin solution, locomotor activity, and alcohol elimination were unaffected.CONCLUSION: Together, these observations support a specific involvement of the MCH system in mediating alcohol reward and cue-induced relapse to alcohol seeking. MCH1-R antagonism may constitute an attractive treatment target for alcohol use disorders.
