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Jenner P, Falup-Pecurariu C, Leta V, Verin M, Auffret M, Bhidayasiri R, Weiss D, Borovečki F, Jost WH. Adopting the Rumsfeld approach to understanding the action of levodopa and apomorphine in Parkinson's disease. J Neural Transm (Vienna) 2023; 130:1337-1347. [PMID: 37210460 PMCID: PMC10645644 DOI: 10.1007/s00702-023-02655-0] [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: 04/04/2023] [Accepted: 05/14/2023] [Indexed: 05/22/2023]
Abstract
Dopaminergic therapies dominate the treatment of the motor and non-motor symptoms of Parkinson's disease (PD) but there have been no major advances in therapy in many decades. Two of the oldest drugs used appear more effective than others-levodopa and apomorphine-but the reasons for this are seldom discussed and this may be one cause for a lack of progress. This short review questions current thinking on drug action and looks at whether adopting the philosophy of ex-US Secretary of State Donald Rumsfeld reveals 'unknown' aspects of the actions of levodopa and apomorphine that provide clues for a way forward. It appears that both levodopa and apomorphine have a more complex pharmacology than classical views would suggest. In addition, there are unexpected facets to the mechanisms through which levodopa acts that are either forgotten as 'known unknowns' or ignored as 'unknown unknowns'. The conclusion reached is that we may not know as much as we think about drug action in PD and there is a case for looking beyond the obvious.
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Affiliation(s)
- P Jenner
- Faculty of Life Sciences and Medicine, Institute of Pharmaceutical Sciences, King's College London, London, SE1 1UL, UK.
| | - C Falup-Pecurariu
- Department of Neurology, Transylvania University, 500036, Brasov, Romania
| | - V Leta
- Parkinson's Foundation Center of Excellence at King's College Hospital; Department of Basic and Clinical Neuroscience, The Maurice Wohl Clinical Neuroscience Institute, King's College London and National Institute for Health Research (NIHR) Mental Health Biomedical Research Centre, Institute of Psychology, Psychiatry and Neurosciences, King's College London, London, UK
| | - M Verin
- Institut des Neurosciences Cliniques de Rennes (INCR); Behavior and Basal Ganglia Research Unit, CIC-IT, CIC1414, Pontchaillou University Hospital and University of Rennes, Rennes, France
| | - M Auffret
- Institut des Neurosciences Cliniques de Rennes (INCR); Behavior and Basal Ganglia Research Unit, CIC-IT, CIC1414, Pontchaillou University Hospital and University of Rennes, Rennes, France
- France Développement Electronique (FDE), Monswiller, France
| | - Roongroj Bhidayasiri
- Department of Medicine, Faculty of Medicine, Chulalongkorn Centre of Excellence for Parkinson's Disease and Related Disorders, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Thai Red Cross Society, Bangkok, 10330, Thailand
- The Academy of Science, The Royal Society of Thailand, Bangkok, 10330, Thailand
| | - D Weiss
- Department for Neurodegenerative Diseases, Centre for Neurology, Hertie-Institute for Clinical Brain Research, Hoppe-Seyler-Str. 3, 72076, Tübingen, Germany
| | - F Borovečki
- Division for Neurodegenerative Diseases and Neurogenomics, Department of Neurology, University Hospital Centre Zagreb, 10000, Zagreb, Croatia
| | - W H Jost
- Parkinson-Klinik Ortenau, Kreuzbergstr. 12-16, 77709, Wolfach, Germany
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2
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Juza R, Musilek K, Mezeiova E, Soukup O, Korabecny J. Recent advances in dopamine D 2 receptor ligands in the treatment of neuropsychiatric disorders. Med Res Rev 2023; 43:55-211. [PMID: 36111795 DOI: 10.1002/med.21923] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2021] [Revised: 07/29/2022] [Accepted: 08/09/2022] [Indexed: 02/04/2023]
Abstract
Dopamine is a biologically active amine synthesized in the central and peripheral nervous system. This biogenic monoamine acts by activating five types of dopamine receptors (D1-5 Rs), which belong to the G protein-coupled receptor family. Antagonists and partial agonists of D2 Rs are used to treat schizophrenia, Parkinson's disease, depression, and anxiety. The typical pharmacophore with high D2 R affinity comprises four main areas, namely aromatic moiety, cyclic amine, central linker and aromatic/heteroaromatic lipophilic fragment. From the literature reviewed herein, we can conclude that 4-(2,3-dichlorophenyl), 4-(2-methoxyphenyl)-, 4-(benzo[b]thiophen-4-yl)-1-substituted piperazine, and 4-(6-fluorobenzo[d]isoxazol-3-yl)piperidine moieties are critical for high D2 R affinity. Four to six atoms chains are optimal for D2 R affinity with 4-butoxyl as the most pronounced one. The bicyclic aromatic/heteroaromatic systems are most frequently occurring as lipophilic appendages to retain high D2 R affinity. In this review, we provide a thorough overview of the therapeutic potential of D2 R modulators in the treatment of the aforementioned disorders. In addition, this review summarizes current knowledge about these diseases, with a focus on the dopaminergic pathway underlying these pathologies. Major attention is paid to the structure, function, and pharmacology of novel D2 R ligands, which have been developed in the last decade (2010-2021), and belong to the 1,4-disubstituted aromatic cyclic amine group. Due to the abundance of data, allosteric D2 R ligands and D2 R modulators from patents are not discussed in this review.
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Affiliation(s)
- Radomir Juza
- Experimental Neurobiology, National Institute of Mental Health, Klecany, Czech Republic.,Department of Chemistry, Faculty of Science, University of Hradec Kralove, Hradec Kralove, Czech Republic
| | - Kamil Musilek
- Department of Chemistry, Faculty of Science, University of Hradec Kralove, Hradec Kralove, Czech Republic.,Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic
| | - Eva Mezeiova
- Experimental Neurobiology, National Institute of Mental Health, Klecany, Czech Republic.,Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic
| | - Ondrej Soukup
- Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic
| | - Jan Korabecny
- Experimental Neurobiology, National Institute of Mental Health, Klecany, Czech Republic.,Biomedical Research Centre, University Hospital Hradec Kralove, Hradec Kralove, Czech Republic
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3
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Thomas Broome S, Castorina A. Systemic Rotenone Administration Causes Extra-Nigral Alterations in C57BL/6 Mice. Biomedicines 2022; 10:biomedicines10123174. [PMID: 36551930 PMCID: PMC9775048 DOI: 10.3390/biomedicines10123174] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Revised: 12/01/2022] [Accepted: 12/05/2022] [Indexed: 12/14/2022] Open
Abstract
Systemic administration of rotenone replicates several pathogenic and behavioural features of Parkinson's disease (PD), some of which cannot be explained by deficits of the nigrostriatal pathway. In this study, we provide a comprehensive analysis of several neurochemical alterations triggered by systemic rotenone administration in the CNS of C57BL/6 mice. Mice injected with either 1, 3 or 10 mg/kg rotenone daily via intraperitoneal route for 21 days were assessed weekly for changes in locomotor and exploratory behaviour. Rotenone treatment caused significant locomotor and exploratory impairment at dosages of 3 or 10 mg/kg. Molecular analyses showed reductions of both TH and DAT expression in the midbrain, striatum and spinal cord, accompanied by altered expression of dopamine receptors and brain-derived neurotrophic factor (BDNF). Rotenone also triggered midbrain-restricted inflammatory responses with heightened expression of glial markers, which was not seen in extra-nigral regions. However, widespread alterations of mitochondrial function and increased signatures of oxidative stress were identified in both nigral and extra-nigral regions, along with disruptions of neuroprotective peptides, such as pituitary adenylate cyclase-activating polypeptide (PACAP), vasoactive intestinal peptide (VIP) and activity-dependent neuroprotective protein (ADNP). Altogether, this study shows that systemic rotenone intoxication, similarly to PD, causes a series of neurochemical alterations that extend at multiple CNS levels, reinforcing the suitability of this pre-clinical model for the study extra-nigral defects of PD.
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4
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Biological Potential, Gastrointestinal Digestion, Absorption, and Bioavailability of Algae-Derived Compounds with Neuroprotective Activity: A Comprehensive Review. Mar Drugs 2022; 20:md20060362. [PMID: 35736165 PMCID: PMC9227170 DOI: 10.3390/md20060362] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 05/23/2022] [Accepted: 05/24/2022] [Indexed: 12/04/2022] Open
Abstract
Currently, there is no known cure for neurodegenerative disease. However, the available therapies aim to manage some of the symptoms of the disease. Human neurodegenerative diseases are a heterogeneous group of illnesses characterized by progressive loss of neuronal cells and nervous system dysfunction related to several mechanisms such as protein aggregation, neuroinflammation, oxidative stress, and neurotransmission dysfunction. Neuroprotective compounds are essential in the prevention and management of neurodegenerative diseases. This review will focus on the neurodegeneration mechanisms and the compounds (proteins, polyunsaturated fatty acids (PUFAs), polysaccharides, carotenoids, phycobiliproteins, phenolic compounds, among others) present in seaweeds that have shown in vivo and in vitro neuroprotective activity. Additionally, it will cover the recent findings on the neuroprotective effects of bioactive compounds from macroalgae, with a focus on their biological potential and possible mechanism of action, including microbiota modulation. Furthermore, gastrointestinal digestion, absorption, and bioavailability will be discussed. Moreover, the clinical trials using seaweed-based drugs or extracts to treat neurodegenerative disorders will be presented, showing the real potential and limitations that a specific metabolite or extract may have as a new therapeutic agent considering the recent approval of a seaweed-based drug to treat Alzheimer’s disease.
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5
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Liu Y, Tao S, Liao L, Li Y, Li H, Li Z, Lin L, Wan X, Yang X, Chen L. TRIM25 promotes the cell survival and growth of hepatocellular carcinoma through targeting Keap1-Nrf2 pathway. Nat Commun 2020; 11:348. [PMID: 31953436 PMCID: PMC6969153 DOI: 10.1038/s41467-019-14190-2] [Citation(s) in RCA: 142] [Impact Index Per Article: 35.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2019] [Accepted: 12/18/2019] [Indexed: 12/20/2022] Open
Abstract
Tumor cells often exhibit augmented capacity to maintain endoplasmic reticulum (ER) homeostasis under adverse conditions, yet the underlying mechanisms are not well defined. Here, through the evaluation of all human TRIM proteins, we find that TRIM25 is significantly induced upon ER stress. Upregulation of TRIM25 ameliorates oxidative stress, promotes ER-associated degradation (ERAD), and reduces IRE1 signaling in the UPR pathway. In contrast, depletion of TRIM25 leads to ER stress and attenuates tumor cell growth in vitro and in vivo. Mechanistically, TRIM25 directly targets Keap1 by ubiquitination and degradation. This leads to Nrf2 activation, which bolsters anti-oxidant defense and cell survival. TRIM25 expression is positively associated with Nrf2 expression and negatively with Keap1 expression in hepatocellular carcinoma (HCC) xenografts and specimens. Moreover, high TRIM25 expression correlates with poor patient survival in HCC. These findings reveal TRIM25 as a regulator of ER homeostasis and a potential target for tumor therapy. The unfolded protein response allows tumour cells to adapt to ER stress, and aberrant activation of Nrf2 confers cancer progression. Here, the authors show that TRIM25 is induced during ER stress and promotes tumour cell survival by targeting Keap1 for degradation, leading to Nrf2 activation.
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Affiliation(s)
- Yanfeng Liu
- Shenzhen Laboratory of Tumor Cell Biology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China.,Stem Cell Research Center, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, 200127, China
| | - Shishi Tao
- Shenzhen Laboratory of Tumor Cell Biology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Lijuan Liao
- Shenzhen Laboratory of Tumor Cell Biology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Yang Li
- Shenzhen Laboratory of Tumor Cell Biology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Hongchang Li
- Shenzhen Laboratory of Tumor Cell Biology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Zhihuan Li
- Dongguan Enlife Stem Cell Biotechnology Institute, Zheshang Building, #430 Dongguan Ave., Dongguan, Guangdong, 523000, China
| | - Lilong Lin
- Dongguan Enlife Stem Cell Biotechnology Institute, Zheshang Building, #430 Dongguan Ave., Dongguan, Guangdong, 523000, China
| | - Xiaochun Wan
- Shenzhen Laboratory of Tumor Cell Biology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China
| | - Xiaolu Yang
- Department of Cancer Biology and Abramson Family Cancer Research Institute, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
| | - Liang Chen
- Shenzhen Laboratory of Tumor Cell Biology, Institute of Biomedicine and Biotechnology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, 518055, P. R. China.
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6
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Jatana N, Thukral L, Latha N. Structure and dynamics of DRD4 bound to an agonist and an antagonist using in silico
approaches. Proteins 2015; 83:867-80. [DOI: 10.1002/prot.24716] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2014] [Revised: 09/15/2014] [Accepted: 09/27/2014] [Indexed: 01/11/2023]
Affiliation(s)
- Nidhi Jatana
- Bioinformatics Infrastructure Facility; Sri Venkateswara College (University of Delhi); Benito Juarez Road Dhaula Kuan New Delhi 110 021 India
| | - Lipi Thukral
- CSIR-Institute of Genomics and Integrative Biology; Mall Road New Delhi 110 007 India
| | - N. Latha
- Bioinformatics Infrastructure Facility; Sri Venkateswara College (University of Delhi); Benito Juarez Road Dhaula Kuan New Delhi 110 021 India
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7
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Gui YX, Wan Y, Xiao Q, Wang Y, Wang G, Chen SD. Verification of expressions of Kir2 as potential peripheral biomarkers in lymphocytes from patients with Parkinson's disease. Neurosci Lett 2011; 505:104-8. [PMID: 22001575 DOI: 10.1016/j.neulet.2011.09.070] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2011] [Revised: 09/20/2011] [Accepted: 09/30/2011] [Indexed: 10/16/2022]
Abstract
Prior studies have reported gene expression alterations in peripheral blood lymphocytes (PBLs) obtained from patients with Parkinson's disease (PD) as compared to healthy controls. These alterations can not only be regarded as potential biomarkers, but also enhance understanding of the pathogenic mechanism of PD. In the present study, the gene expression levels of dopamine receptor (D2, D3), inward rectified potassium channels subunits Kir2 (Kir2.1, Kir2.2, Kir2.3, Kir2.4) and ATP-sensitive potassium channel subunit Kir6.2 in PBLs were analyzed using quantitative real-time PCR among 20 PD patients with medication, 10 PD patients without medication and 16 healthy controls, respectively. The results showed that there was a significantly decrease of the D2, D3 mRNA expression in PBLs of PD patients compared with that in healthy controls. The four inward rectified potassium channels Kir2.1, Kir2.2, Kir2.3, and Kir2.4 mRNA expression in PBLs from PD patients were also significantly down-regulated than that from age-matched healthy controls. However, there was no apparent difference in expression of another potassium channel Kir6.2 mRNA between PD patients and healthy controls. We proposed that the Kir2 potassium channels mRNA on blood lymphocytes may be regarded as a potential biomarker for PD screening.
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Affiliation(s)
- Ya-Xing Gui
- Department of Neurology & Institute of Neurology, Ruijin Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200025, China
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8
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Kirch DG, Taylor TR, Creese I, Xu SX, Wyatt RJ. Effect of Chronic Nicotine Treatment and Withdrawal on Rat Striatal D1 and D2 Dopamine Receptors. J Pharm Pharmacol 2011; 44:89-92. [PMID: 1352822 DOI: 10.1111/j.2042-7158.1992.tb03567.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Abstract
The effects on rat striatal dopamine receptors after chronic nicotine administration (3 and 12 mg kg−1 day−1), and after withdrawal from chronic nicotine (12 mg kg−1 day−1), were studied. After 21 days of continuous minipump infusion, the control (saline) and nicotine-treated rats were killed. The nicotine-withdrawal rats were killed on day 28, 7 days after pump removal. Radioligand studies were performed to determine D1 ([3H]SCH23390) and D2 ([3H]spiperone) striatal dopamine receptor affinity (Kd) and maximum binding (Bmax). Dopamine inhibition of antagonist binding at 3 concentrations and the effect of 0·3 Mm GTP on binding affinity were examined. No statistically significant differences between control and nicotine treatment or withdrawal groups were noted in either D1 or D2 receptor Kd or Bmax. Although nicotine has been shown to affect nigrostriatal dopamine release, chronic treatment does not appear to alter overall striatal dopaminergic receptor binding parameters.
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Affiliation(s)
- D G Kirch
- Neuropsychiatry Branch, National Institute of Mental Health, Rockville, Maryland 20857
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9
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Doudet DJ, Holden JE, Jivan S, McGeer E, Wyatt RJ. In vivo PET studies of the dopamine D2 receptors in rhesus monkeys with long-term MPTP-induced parkinsonism. Synapse 2000; 38:105-13. [PMID: 11018784 DOI: 10.1002/1098-2396(200011)38:2<105::aid-syn1>3.0.co;2-s] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Studies of dopamine (DA) receptor binding in early parkinsonian patients, or in models of Parkinson's disease, have revealed a supersensitivity of the D2-like receptor subtype as compared to age-matched controls. The lack of upregulation in advanced patients is often attributed to the effects of prolonged antiparkinsonian therapy, but the impact of therapy vs. intrinsic mechanisms in untreated patients or animals with long-term lesions of the DA nigrostriatal pathway has been difficult to address. We studied, in vivo, by PET using the DA D2 receptor ligand raclopride, the status of the DA receptors in normal rhesus monkeys and those with acute (3 months) or long-term (10 years) MPTP-induced nigrostriatal lesions. Compared to age-matched controls, there was no change in raclopride binding in MPTP-treated animals without parkinsonian symptoms. There was a significant increase in raclopride binding in the putamen (but not caudate nucleus) of all the animals displaying rigidity, hypo- and bradykinesia. This increase was greater in the animals with acute lesions (32%) than with established, long-term lesions (18%). There was no correlation between the postmortem striatal DA concentrations and in vivo raclopride binding but there was a correlation between PET raclopride binding and [(3)H]raclopride binding in vitro. Complex changes in D2 receptor binding occur in various stages of parkinsonism. Antiparkinsonian therapy is unlikely to be solely responsible for the lack of upregulation found in advanced parkinsonian patients but may be a contributing factor.
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Affiliation(s)
- D J Doudet
- Department of Medicine, Division of Neurology and Kinsmen Laboratory of Neurological Research and TRIUMF, University of British Columbia, Vancouver, BC, Canada.
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10
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MacLennan AJ, Lee N, Vincent SR, Walker DW. D2 dopamine receptor mRNA distribution in cholinergic and somatostatinergic cells of the rat caudate-putamen and nucleus accumbens. Neurosci Lett 1994; 180:214-8. [PMID: 7700582 DOI: 10.1016/0304-3940(94)90523-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
An in situ hybridization procedure that identifies cells expressing D2 dopamine receptor mRNA was combined in double-labelling studies with immunohistochemical procedures that identify cells expressing either choline acetyltransferase (ChAT) or somatostatin. D2 receptor mRNA was detected in almost all of the ChAT positive caudate-putamen cells, approximately half of the ChAT positive nucleus accumbens cells and none of the somatostatin-positive cells in either brain region.
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Affiliation(s)
- A J MacLennan
- Department of Neuroscience, University of Florida College of Medicine, Gainesville 32610
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11
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Volkow ND, Fowler JS, Wang GJ, Hitzemann R, Logan J, Schlyer DJ, Dewey SL, Wolf AP. Decreased dopamine D2 receptor availability is associated with reduced frontal metabolism in cocaine abusers. Synapse 1993; 14:169-77. [PMID: 8101394 DOI: 10.1002/syn.890140210] [Citation(s) in RCA: 601] [Impact Index Per Article: 19.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Decreased dopaminergic function has been postulated to underlie cocaine addiction. To examine the possibility that dysfunction of brain regions subserved by the dopamine system could promote cocaine self-administration, positron emission tomography and a dual-tracer approach was used to examine dopamine D2 receptor availability and regional brain glucose metabolism in cocaine abusers. When compared to normal controls, cocaine abusers showed significant decreases in dopamine D2 receptor availability which persisted 3-4 months after detoxification. Decreases in dopamine D2 receptor availability were associated with decreased metabolism in several regions of the frontal lobes, most markedly orbito-frontal cortex and cingulate gyri. Dopamine dysregulation of these brain areas which are involved in the channeling of drive and affect could lead to loss of control resulting in compulsive drug-taking behavior.
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Affiliation(s)
- N D Volkow
- Medical Department, Brookhaven National Laboratory, Upton, New York 11973
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12
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Abstract
Dopamine receptors in the human brain play an important role in the pathophysiology and treatment of psychosis and movement disorders. Pharmacological and biochemical studies, and more recently gene cloning techniques, have demonstrated that there are multiple receptors for dopamine in the brain. There is confusion in the literature as new subtypes (D3, D4 and D5 receptors) were classified according to unspecified criteria. At present, however, all subtypes of dopamine receptors that have been identified still fit in the traditional D1/D2 dopamine receptor classification scheme. In this article, a more hierarchical system of nomenclature is proposed and our insights into the distribution and localization of the dopamine receptor subtypes in human brain are summarized. Although the current status of the different subtypes of the D1 and D2 receptor families in human brain remains unclear, their discovery has created hope for the development of more efficacious and specific medicines with less side-effects.
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Affiliation(s)
- J De Keyser
- Department of Neurology, Academisch Ziekenhuis Vrije Universiteit Brussel, Belgium
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13
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14
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Rinne JO, Laihinen A, Lönnberg P, Marjamäki P, Rinne UK. A post-mortem study on striatal dopamine receptors in Parkinson's disease. Brain Res 1991; 556:117-22. [PMID: 1834312 DOI: 10.1016/0006-8993(91)90554-9] [Citation(s) in RCA: 63] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Striatal dopamine D1 and D2 receptors were investigated in 49 patients with Parkinson's disease (PD) and 33 age-matched controls with [3H]SCH 23390 and [3H]spiroperidol as ligands respectively. A full Scatchard analysis giving Bmax and Kd values was performed. In the caudate nucleus, a small but significant decrease in the number of D1 and D2 receptors was seen, whereas in the putamen the number of dopamine receptors was unchanged. Treatment with neuroleptics was found to increase the number of D2 receptors both in the caudate nucleus and putamen. The number of neither D1 nor D2 receptors correlated neither with the duration of disease or levodopa treatment of the patients nor with the post-mortem delay or storage time of the samples. Furthermore, no association was found between either D1 or D2 receptor number and clinical variables of the patients. The activity of choline acetyltransferase (ChAT) was found to be unchanged in the striatum, whereas a marked decline was seen in the hippocampus and cortical areas, indicating that intrinsic striatal cholinergic neurons are not affected in PD. The present results suggest that there is a modest decline in the number of striatal dopamine D2 receptors in advanced patients with PD at the end stage of the disease.
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Affiliation(s)
- J O Rinne
- Department of Neurology, University of Turku, Finland
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15
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Donnan GA, Woodhouse DG, Kaczmarczyk SJ, Holder JE, Paxinos G, Chilco PJ, Churchyard AJ, Kalnins RM, Fabinyi GC, Mendelsohn FA. Evidence for plasticity of the dopaminergic system in parkinsonism. Mol Neurobiol 1991; 5:421-33. [PMID: 1823144 DOI: 10.1007/bf02935563] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
A series of compensatory mechanisms within the dopaminergic system have been shown to maintain clinical function in the presence of dopamine loss. Experimental evidence for increased presynaptic dopamine turnover owing to increased dopamine synthesis, release, and reduced reuptake exists. Direct evidence that these mechanisms maintain extracellular dopamine levels is provided by intracerebral microdialysis techniques. Postsynaptic denervation supersensitivity clearly occurs with D2 dopamine receptors, although this is less evident with D1 receptors. Similarly, mechanisms of plasticity have been shown to be relevant in human postmortem and Positron Emission Tomographic studies of patients with Parkinson's disease. However, although presynaptic increases in dopamine turnover are well documented, postsynaptic D1 and D2 receptor changes have been more difficult to establish, mainly because of methodological difficulties. D2, but not D1, receptor increases have been documented in drug naive Parkinsonian patients with PET techniques. In transplantation of adrenal gland to striatum in animal models and patients with Parkinsonism where clinical improvement occurs, plasticity of host response may be as important as plasticity of the graft. Although some elements of the compensatory mechanism of dopamine plasticity may be deleterious, such as dyskinesias owing to dopamine receptor supersensitivity, the overall effect of delay and minimization of the clinical expression of disease is advantageous. An even greater understanding of the mechanisms involved may assist in developing future therapeutic strategies.
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Affiliation(s)
- G A Donnan
- Department of Neurology, Austin Hospital, Heidelberg, Victoria, Australia
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16
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Rinne JO, Laihinen A, Någren K, Bergman J, Solin O, Haaparanta M, Ruotsalainen U, Rinne UK. PET demonstrates different behaviour of striatal dopamine D-1 and D-2 receptors in early Parkinson's disease. J Neurosci Res 1990; 27:494-9. [PMID: 1981915 DOI: 10.1002/jnr.490270409] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Striatal dopamine D-1 receptor binding was investigated in vivo with positron emission tomography (PET) in five patients with early Parkinson's disease using [11C]-SCH 23390. All patients had predominantly unilateral symptoms and showed a significant reduction in the accumulation of [18F]-6-F-DOPA in the striatum contralateral to the symptoms. None of the patients had received any antiparkinsonian medication. The striatal and cerebellar radioactivity was measured and corresponding striatum/cerebellum ratios were counted. The mean striatum/cerebellum ratio of [11C]-SCH 23390 binding was symmetric between the hemispheres. By contrast, the striatum/cerebellum ratio of [11C]raclopride binding, labelling dopamine D-2 receptors, was increased significantly in the hemisphere contralateral to the symptoms as compared with the opposite hemisphere. Thus, the present results show that the behaviour of striatal D-1 and D-2 receptors is different in early Parkinson's disease.
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Affiliation(s)
- J O Rinne
- Department of Neurology, University of Turku, Finland
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17
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John MacLennan A, Frantz GD, Weatherwax RC, Tillakaratne NJ, Tobin AJ. Expression of mRNAs that encode D2 dopamine receptor subtypes: Anatomical, developmental, and pharmacological studies. Mol Cell Neurosci 1990; 1:151-60. [DOI: 10.1016/1044-7431(90)90020-5] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/21/1990] [Indexed: 10/20/2022] Open
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Abstract
Dopamine D1 and D2 receptor binding was investigated in the caudate nucleus and putamen in 65 individuals ranging from 6 to 93 years of age. [3H]SCH 23390 and [3H]spiroperidol were used as ligands for D1 and D2 receptors, respectively. A full Scatchard analysis with several ligand concentrations was performed yielding Bmax and Kd values. The number of D1 and D2 receptors declined with age both in the caudate nucleus and putamen without any change in the mean dissociation constant. The ratio of D1:D2 receptors remained unchanged. The results show that the dopaminergic system degenerates in the aging striatum and may contribute to the frequent occurrence of extrapyramidal symptoms in the elderly.
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