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Riveros ME, Leibold NK, Retamal MA, Ezquer F. Role of histaminergic regulation of astrocytes in alcohol use disorder. Prog Neuropsychopharmacol Biol Psychiatry 2024; 133:111009. [PMID: 38653364 DOI: 10.1016/j.pnpbp.2024.111009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2023] [Revised: 02/26/2024] [Accepted: 04/14/2024] [Indexed: 04/25/2024]
Abstract
Alcohol use disorder (AUD) is a severe, yet not fully understood, mental health problem. It is associated with liver, pancreatic, and gastrointestinal diseases, thereby highly increasing the morbidity and mortality of these individuals. Currently, there is no effective and safe pharmacological therapy for AUD. Therefore, there is an urgent need to increase our knowledge about its neurophysiological etiology to develop new treatments specifically targeted at this health condition. Recent findings have shown an upregulation in the histaminergic system both in alcohol dependent individuals and in animals with high alcohol preference. The use of H3 histaminergic receptor antagonists has given promising therapeutic results in animal models of AUD. Interestingly, astrocytes, which are ubiquitously present in the brain, express the three main histamine receptors (H1, H2 and H3), and in the last few years, several studies have shown that astrocytes could play an important role in the development and maintenance of AUD. Accordingly, alterations in the density of astrocytes in brain areas such as the prefrontal cortex, ventral striatum, and hippocampus that are critical for AUD-related characteristics have been observed. These characteristics include addiction, impulsivity, motor function, and aggression. In this work, we review the current state of knowledge on the relationship between the histaminergic system and astrocytes in AUD and propose that histamine could increase alcohol tolerance by protecting astrocytes from ethanol-induced oxidative stress. This increased tolerance could lead to high levels of alcohol intake and therefore could be a key factor in the development of alcohol dependence.
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Affiliation(s)
- María Eugenia Riveros
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile.
| | - Nicole K Leibold
- Department of Psychiatry and Neuropsychology, School for Mental Health and Neuroscience (MHeNs), Faculty of Health and Life Sciences (FHML), Maastricht University, Maastricht, the Netherlands
| | - Mauricio A Retamal
- Centro de Fisiología Celular e Integrativa, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile; Programa de Comunicación Celular en Cáncer, Instituto de Ciencia e Innovación en Medicina, Facultad de Medicina, Clínica Alemana Universidad del Desarrollo, Santiago, Chile
| | - Fernando Ezquer
- Centro de Medicina Regenerativa, Instituto de Ciencia e Innovación en Medicina, Facultad de Medicina Clínica Alemana, Universidad del Desarrollo, Santiago. Chile; Research Center for the Development of Novel Therapeutic Alternatives for Alcohol Use Disorders, Santiago, Chile
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2
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Oka M, Yoshino R, Kitanaka N, Hall FS, Uhl GR, Kitanaka J. Role of glycogen synthase kinase-3β in dependence and abuse liability of alcohol. Alcohol Alcohol 2024; 59:agad086. [PMID: 38145944 DOI: 10.1093/alcalc/agad086] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2023] [Revised: 11/25/2023] [Accepted: 11/28/2023] [Indexed: 12/27/2023] Open
Abstract
BACKGROUND Alcohol is a major abused drug worldwide that contributes substantially to health and social problems. These problems result from acute alcohol overuse as well as chronic use, leading to alcohol use disorder (AUD). A major goal of this field is to establish a treatment for alcohol abuse and dependence in patients with AUD. The central molecular mechanisms of acute alcohol actions have been extensively investigated in rodent models. AIMS One of the central mechanisms that may be involved is glycogen synthase kinase-3β (GSK-3β) activity, a key enzyme involved in glycogen metabolism but which has crucial roles in numerous cellular processes. Although the exact mechanisms leading from acute alcohol actions to these chronic changes in GSK-3β function are not yet clear, GSK-3β nonetheless constitutes a potential therapeutic target for AUD by reducing its function using GSK-3β inhibitors. This review is focused on the correlation between GSK-3β activity and the degree of alcohol consumption. METHODS Research articles regarding investigation of effect of GSK-3β on alcohol consumption in rodents were searched on PubMed, Embase, and Scopus databases using keywords "glycogen synthase kinase," "alcohol (or ethanol)," "intake (or consumption)," and evaluated by changes in ratios of pGSK-3βSer9/pGSK-3β. RESULTS In animal experiments, GSK-3β activity decreases in the brain under forced and voluntary alcohol consumption while GSK-3β activity increases under alcohol-seeking behavior. CONCLUSIONS Several pieces of evidence suggest that alterations in GSK-3β function are important mediators of chronic ethanol actions, including those related to alcohol dependence and the adverse effects of chronic ethanol exposure.
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Affiliation(s)
- Masahiro Oka
- Laboratory of Drug Addiction and Experimental Therapeutics, Department of Pharmacy, School of Pharmacy, Hyogo Medical University, 1-3-6 Minatojima, Chuo-ku, Kobe, Hyogo 650-8530, Japan
| | - Rui Yoshino
- Laboratory of Drug Addiction and Experimental Therapeutics, Department of Pharmacy, School of Pharmacy, Hyogo Medical University, 1-3-6 Minatojima, Chuo-ku, Kobe, Hyogo 650-8530, Japan
| | - Nobue Kitanaka
- Department of Pharmacology, School of Medicine, Hyogo Medical University, Nishinomiya, Hyogo 663-8501, Japan
| | - F Scott Hall
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Frederic and Mary Wolfe Center HEB 282D, Mail Stop 1015, 3000 Arlington Avenue,Toledo, OH 43614, United States
| | - George R Uhl
- Neurology Service, VA Maryland Healthcare System, 10 North Greene Street, Baltimore, MD 21201, United States
- Departments of Neurology and Pharmacology, University of Maryland School of Medicine, 655 W. Baltimore Street, Baltimore, MD 21201, United States
| | - Junichi Kitanaka
- Laboratory of Drug Addiction and Experimental Therapeutics, Department of Pharmacy, School of Pharmacy, Hyogo Medical University, 1-3-6 Minatojima, Chuo-ku, Kobe, Hyogo 650-8530, Japan
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Di Ciano P, Hendershot CS, Le Foll B. Therapeutic Potential of Histamine H3 Receptors in Substance Use Disorders. Curr Top Behav Neurosci 2022; 59:169-191. [PMID: 35704272 DOI: 10.1007/7854_2022_372] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Substance use disorders are a leading cause of morbidity and mortality, and available pharmacological treatments are of modest efficacy. Histamine is a biogenic amine with four types of receptors. The histamine H3 receptor (H3R) is an autoreceptor and also an heteroreceptor. H3Rs are highly expressed in the basal ganglia, hippocampus and cortex, and regulate a number of neurotransmitters including acetylcholine, norepinephrine, GABA and dopamine. Its function and localization suggest that the H3R may be relevant to a number of psychiatric disorders and could represent a potential therapeutic target for substance use disorders. The purpose of the present review is to summarize preclinical studies investigating the effects of H3R agonists and antagonists on animal models of alcohol, nicotine and psychostimulant use. At present, the effects of H3R antagonists such as thioperamide, pitolisant or ciproxifan have been investigated in drug-induced locomotion, conditioned place preference, drug self-administration, reinstatement, sensitization and drug discrimination. For alcohol and nicotine, the effects of H3R ligands on two-bottle choice and memory tasks, respectively, have also been investigated. The results of these studies are inconsistent. For alcohol, H3R antagonists generally decreased the reward-related properties of ethanol, which suggests that H3R antagonists may be effective as a treatment option for alcohol use disorder. However, the effects of H3R antagonists on nicotine and psychostimulant motivation and reward are less clear. H3R antagonists potentiated the abuse-related properties of nicotine, but only a handful of studies have been conducted. For psychostimulants, evidence is mixed and suggests that more research is needed to establish whether H3R antagonists are a viable therapeutic option. The fact that different drugs of abuse have different brain targets may explain the differential effects of H3R ligands.
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Affiliation(s)
- Patricia Di Ciano
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada
- Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, Toronto, ON, Canada
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada
| | - Christian S Hendershot
- Bowles Center for Alcohol Studies, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
- Department of Psychiatry, University of North Carolina at Chapel Hill, Chapel Hill, NC, USA
| | - Bernard Le Foll
- Department of Pharmacology and Toxicology, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
- Institute for Mental Health Policy Research, Centre for Addiction and Mental Health, Toronto, ON, Canada.
- Campbell Family Mental Health Research Institute, Centre for Addiction and Mental Health, Toronto, ON, Canada.
- Translational Addiction Research Laboratory, Centre for Addiction and Mental Health, Toronto, ON, Canada.
- Department of Psychiatry, Faculty of Medicine, University of Toronto, Toronto, ON, Canada.
- Addictions Division, Centre for Addiction and Mental Health, Toronto, ON, Canada.
- Department of Family and Community Medicine, University of Toronto, Toronto, ON, Canada.
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4
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Kitanaka N, Hall FS, Tanaka KI, Tomita K, Igarashi K, Nishiyama N, Sato T, Uhl GR, Kitanaka J. Are Histamine H 3 Antagonists the Definitive Treatment for Acute Methamphetamine Intoxication? Curr Drug Res Rev 2022; 14:162-170. [PMID: 35431009 DOI: 10.2174/2589977514666220414122847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/21/2021] [Accepted: 12/31/2021] [Indexed: 06/14/2023]
Abstract
BACKGROUND Methamphetamine (METH) is classified as a Schedule II stimulant drug under the United Nations Convention on Psychotropic Substances of 1971. METH and other amphetamine analogues (AMPHs) are powerful addictive drugs. Treatments are needed to treat the symptoms of METH addiction, chronic METH use, and acute METH overdose. No effective treatment for METH abuse has been established because alterations of brain functions under the excessive intake of abused drug intake are largely irreversible due in part to brain damage that occurs in the course of chronic METH use. OBJECTIVE Modulation of brain histamine neurotransmission is involved in several neuropsychiatric disorders, including substance use disorders. This review discusses the possible mechanisms underlying the therapeutic effects of histamine H3 receptor antagonists on symptoms of methamphetamine abuse. CONCLUSION Treatment of mice with centrally acting histamine H3 receptor antagonists increases hypothalamic histamine contents and reduces high-dose METH effects while potentiating lowdose effects via histamine H3 receptors that bind released histamine. On the basis of experimental evidence, it is hypothesized that histamine H3 receptors may be an effective target for the treatment METH use disorder or other adverse effects of chronic METH use.
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Affiliation(s)
- Nobue Kitanaka
- Department of Pharmacology, Hyogo College of Medicine, Hyogo 663-8501, Japan
| | - F Scott Hall
- Department of Pharmacology and Experimental Therapeutics, College of Pharmacy and Pharmaceutical Sciences, University of Toledo, Toledo, Ohio 43614, USA
| | - Koh-Ichi Tanaka
- Division of Pharmacology, Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Hyogo 650-8530, Japan
| | - Kazuo Tomita
- Department of Applied Pharmacology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan
| | - Kento Igarashi
- Neurology and Research Services, New Mexico VA Healthcare System, Albuquerque, New Mexico 87108, USA
| | - Nobuyoshi Nishiyama
- Division of Pharmacology, Department of Pharmacy, School of Pharmacy, Hyogo University of Health Sciences, Hyogo 650-8530, Japan
| | - Tomoaki Sato
- Department of Applied Pharmacology, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima 890-8544, Japan
| | - George R Uhl
- Neurology and Research Services, New Mexico VA Healthcare System, Albuquerque, New Mexico 87108, USA
- Departments of Neurology, Neuroscience, Molecular Genetics and Microbiology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Junichi Kitanaka
- Department of Pharmacology, Hyogo College of Medicine, Hyogo 663-8501, Japan
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Falkenstein M, Elek M, Stark H. Chemical Probes for Histamine Receptor Subtypes. Curr Top Behav Neurosci 2021; 59:29-76. [PMID: 34595743 DOI: 10.1007/7854_2021_254] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Ligands with different properties and different selectivity are highly needed for in vitro and in vivo studies on the (patho)physiological influence of the chemical mediator histamine and its receptor subtypes. A selection of well-described ligands for the different receptor subtypes and different studies is shown with a particular focus on affinity and selectivity. In addition, compounds with radioactive or fluorescence elements will be presented with their beneficial use for other species or different investigations.
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Affiliation(s)
- Markus Falkenstein
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Duesseldorf, Germany
| | - Milica Elek
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Duesseldorf, Germany
| | - Holger Stark
- Institute of Pharmaceutical and Medicinal Chemistry, Heinrich Heine University Düsseldorf, Duesseldorf, Germany.
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Germundson DL, Vendsel LP, Nagamoto-Combs K. Region-specific regulation of central histaminergic H3 receptor expression in a mouse model of cow's milk allergy. Brain Res 2020; 1749:147148. [PMID: 33035498 DOI: 10.1016/j.brainres.2020.147148] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2020] [Revised: 09/29/2020] [Accepted: 10/01/2020] [Indexed: 01/04/2023]
Abstract
Central histaminergic H3 receptor (H3R) has been extensively investigated as a potential therapeutic target for various neurological and neurodegenerative disorders. Despite promising results in preclinical rodent models, clinical trials have not provided conclusive evidence for the benefit of H3R antagonists to alleviate cognitive and behavioral symptoms of these disorders. Inconsistent pharmacological efficacies may arise from aberrant changes in H3R over time during disease development. Because H3R is involved in feedback inhibition of histamine synthesis and secretion, the expression of the autoreceptor may also be reciprocally regulated by altered histamine levels in a pathological condition. Thus, we investigated H3R expression in a mouse model of cow's milk allergy, a condition associated with increased histamine levels. Mice were sensitized to bovine whey proteins (WP) over 5 weeks and H3R protein and transcript levels were examined in the brain. Substantially increased H3R immunoreactivity was observed in various brain regions of WP-sensitized mice compared to sham mice. Elevated H3R expression was also found in the thalamic/hypothalamic region. The expression of histaminergic H1, but not H2, receptor subtype was also increased in this and the midbrain regions. Unlike the brain, all three histaminergic receptors were increased in the small intestine. These results indicated that the central histaminergic receptors were altered in WP-sensitized mice in a subtype- and region-specific manner, which likely contributed to behavioral changes we observed in these mice. Our study also suggests that altered levels of H3R could be considered during a pharmacological intervention of a neurological disease.
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Affiliation(s)
- Danielle L Germundson
- Department of Pathology, University of North Dakota School of Medicine and Health Sciences, 1301 N. Columbia Rd, Grand Forks, ND, United States
| | - Lane P Vendsel
- Department of Pathology, University of North Dakota School of Medicine and Health Sciences, 1301 N. Columbia Rd, Grand Forks, ND, United States
| | - Kumi Nagamoto-Combs
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, 1301 N. Columbia Rd, Grand Forks, ND, United States.
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Soliani A, Kubota SM, Corrêa MF, Cerutti SM, Fernandes JPS. Differential contribution of H3R antagonism by LINS01 compounds on memory, anxiety-like behaviour and spontaneous locomotor activity in healthy rats. Behav Brain Res 2020; 377:112230. [DOI: 10.1016/j.bbr.2019.112230] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Revised: 09/10/2019] [Accepted: 09/11/2019] [Indexed: 02/06/2023]
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Ghamari N, Zarei O, Arias-Montaño JA, Reiner D, Dastmalchi S, Stark H, Hamzeh-Mivehroud M. Histamine H 3 receptor antagonists/inverse agonists: Where do they go? Pharmacol Ther 2019; 200:69-84. [PMID: 31028835 DOI: 10.1016/j.pharmthera.2019.04.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2018] [Accepted: 04/19/2019] [Indexed: 12/16/2022]
Abstract
Since the discovery of the histamine H3 receptor in 1983, tremendous advances in the pharmacological aspects of H3 receptor antagonists/inverse agonists have been accomplished in preclinical studies. At present, there are several drug candidates that reached clinical trial studies for various indications. However, entrance of these candidates to the pharmaceutical market is not free from challenges, and a variety of difficulties is engaged with their developmental process. In this review, the potential role of H3 receptors in the pathophysiology of various central nervous system, metabolic and allergic diseases is discussed. Thereafter, the current status for H3 receptor antagonists/inverse agonists in ongoing clinical trial studies is reviewed and obstacles in developing these agents are emphasized.
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Affiliation(s)
- Nakisa Ghamari
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; School of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Omid Zarei
- Cellular and Molecular Research Center, Research Institute for Health Development, Kurdistan University of Medical Sciences, Sanandaj, Iran; Neurosciences Research Center, Kurdistan University of Medical Sciences, Sanandaj, Iran
| | - José-Antonio Arias-Montaño
- Departamento de Fisiología, Biofísica y Neurociencias, Centro de Investigación y de Estudios Avanzados del IPN, Av. Instituto Politécnico Nacional 2508, Zacatenco, 07360 Ciudad de México, México
| | - David Reiner
- Heinrich Heine University Düsseldorf, Institute of Pharmaceutical and Medicinal Chemistry, Universitaetsstr. 1, 40225 Duesseldorf, Germany
| | - Siavoush Dastmalchi
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; School of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran
| | - Holger Stark
- Heinrich Heine University Düsseldorf, Institute of Pharmaceutical and Medicinal Chemistry, Universitaetsstr. 1, 40225 Duesseldorf, Germany.
| | - Maryam Hamzeh-Mivehroud
- Biotechnology Research Center, Tabriz University of Medical Sciences, Tabriz, Iran; School of Pharmacy, Tabriz University of Medical Sciences, Tabriz, Iran.
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9
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Panula P. Histamine, histamine H 3 receptor, and alcohol use disorder. Br J Pharmacol 2019; 177:634-641. [PMID: 30801695 DOI: 10.1111/bph.14634] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2018] [Revised: 12/20/2018] [Accepted: 02/11/2019] [Indexed: 12/29/2022] Open
Abstract
Alcohol use disorder is associated with several mental, physical, and social problems. Its treatment is difficult and often requires a combination of pharmacological and behavioural therapy. The brain histaminergic system, one of the wake-active systems that controls whole-brain activity, operates through three neuronal GPCRs. The histamine H3 receptor (Hrh3), which is expressed in many brain areas involved in alcohol drinking and alcohol reward, can be targeted with a number of drugs developed initially for cognitive disorders and/or disorders related to sleep, wakefulness, and alertness. In all rodent alcohol drinking models tested so far, H3 receptor antagonists have reduced alcohol drinking and alcohol-induced place preference and cue-induced alcohol reinstatement. Several H3 receptor antagonists tested and found to be safe for humans could be subjected to clinical tests to treat alcohol use disorder. Preference should be given to short-acting drugs to avoid the sleep problems associated with the wake-maintaining effects of the drugs. LINKED ARTICLES: This article is part of a themed section on New Uses for 21st Century. To view the other articles in this section visit http://onlinelibrary.wiley.com/doi/10.1111/bph.v177.3/issuetoc.
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Affiliation(s)
- Pertti Panula
- Department of Anatomy and Neuroscience Center, University of Helsinki, Helsinki, Finland
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Okeke U, Gultneh Y, Jasinski JP, Butcher RJ. Histamine perchlorate. IUCRDATA 2016. [DOI: 10.1107/s2414314616014814] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022] Open
Abstract
The perchlorate salt of the histamine dication [systematic name: 4-(2-azaniumylethyl)-1H-imidazol-3-ium bis(perchlorate)], C5H11N32+·2ClO4−, crystallizes in the monoclinic space groupP21/cwith two formula units in the asymmetric unit. One of the histamine dications is disordered [occupancies of 0.718 (4) and 0.282 (4)] and two of the four perchlorate anions are disordered [occupancies of 0.735 (6):0.265 (6) and 0.637 (5):0.363 (5)]. There is extensive hydrogen bonding in the structure involving both N—H...O and C—H...O interactions, which link the histamine dications and perchlorate anions into a three-dimensional array.
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Nuutinen S, Panula P, Salminen O. Different Hypothalamic Nicotinic α7 Receptor Expression and Response to Low Nicotine Dose in Alcohol-Preferring and Alcohol-Avoiding Rats. Alcohol Clin Exp Res 2016; 40:329-34. [PMID: 26842251 DOI: 10.1111/acer.12960] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/13/2015] [Accepted: 11/08/2015] [Indexed: 11/29/2022]
Abstract
BACKGROUND The aim of this study was to examine possible differences in nicotinic acetylcholine receptors and responses in rats with genetic preference or avoidance for alcohol. This was done by using 2 rat lines with high alcohol preference (Alko Alcohol [AA]) or alcohol avoidance (Alko Non-Alcohol [ANA]). METHODS Locomotor activity was measured following nicotine and histamine H3 receptor (H3R) antagonist treatment. In situ hybridization and receptor ligand binding experiments were used in drug-naïve animals to examine the expression of different α nicotinic receptor subunits. RESULTS The AA rats were found to be more sensitive to the stimulatory effect of a low dose of nicotine than ANA rats, which were not significantly activated. Combination of histamine H3R antagonist, JNJ-39220675, and nicotine resulted to similar locomotor activation as nicotine alone. To further understand the mechanism underlying the difference in nicotine response in AA and ANA rats, we studied the expression of α5, α6, and α7 nicotinic receptor subunits in specific brain areas of AA and ANA rats. We found no differences in the expression of α5 nicotinic receptor subunits in the medial habenula and hippocampus or in α6 subunit in the ventral tegmental area and substantia nigra. However, the level of α7 nicotinic receptor subunit mRNA was significantly lower in the tuberomamillary nucleus of posterior hypothalamus of alcohol-preferring AA rats than in alcohol-avoiding ANA rats. Also the hypothalamic [125I-α-bungarotoxin binding was lower in AA rats indicating lower levels of α7 nicotinic receptors. CONCLUSIONS The lower expression and receptor binding of α7 nicotinic receptors in the tuberomamillary nucleus of AA rats suggest a difference in the regulation of brain histamine neurons between the rat lines since the α7 nicotinic receptors are located in histaminergic neurons. Stronger nicotine-induced locomotor response, mediated partially via α7 receptors, and previously described high alcohol consumption in AA rats could be explained by the found difference in tuberomamillary α7 receptor levels.
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Affiliation(s)
- Saara Nuutinen
- Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland.,Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Pertti Panula
- Department of Anatomy, Faculty of Medicine, University of Helsinki, Helsinki, Finland.,Neuroscience Center, University of Helsinki, Helsinki, Finland
| | - Outi Salminen
- Division of Pharmacology and Pharmacotherapy, Faculty of Pharmacy, University of Helsinki, Helsinki, Finland
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